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Trying to provide all necessary information about IMMUNITY and IMMUNE SYSTEM

Snake venom|Animal toxin|Toxicology|immunolgy

Posted by Mumtaz khan Tuesday, 31 January 2012 0 comments

SNAKE VENOM:
* Sting Apparatus:
* Poisonous and non-poisonous snakes are distributed in all major continents of the world.
* In India,poisonous snakes found are trait,viper,pit viper,cobra,king cobra and all marine snakes.
* The poison duct opens at the tip of the fangs.
*  The poison apparatus consists of a pair of venom gland,a pair of venom ducts and a pair of large pointed fangs.
* The venom gland is located superficially behind the eye of the snake.

* Venom:
* The snake venoms are mixtures of proteins,polypeptides and enzymes.
* The venoms of snakes can be categorised based upon the area they affect.
* They categorised as neurotoxins,Cardiotoxins,Necrotics and Haemolytic venoms.
* Neurotoxins that affect the brain include Proteases,Invertases,DNAases,RNAases.
* Cardiotoxins that affect the heart include vasoconstrictors,vasodilators,serotonic,prostaglandins.
* Necrotics caused by the snake venom include collagenases,hyaluridases,invertases,DNAases,RNAases.

* Effects:
* In snake bite there is rapid swelling and decoloration at the site of bite.
* This is followed by further swelling that may extend all over the body.
* The victim shows signs of vomitting,nausea and diarrhea.In some cases death is caused due to shock.
* The swelling is extremely sensitive to touch and painful.
* When the heart is affected the pulse are weak and is fall in systemic arterial blood pressure.
* when CNS is affected respiratory paralysis in severe cases of poisoning is seen.
* Due to snake bites interference in breathing and eating is experienced.
* Sometimes a blood stained froth is discharged from the nose due to heavy tissue destruction.
* The healing wound is very slow because necrosis causes

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Scorpion|Animal toxin|Immunology|Toxicology

Posted by Mumtaz khan Monday, 30 January 2012 0 comments


SCORPION:
Classification:
Phylum-Arthropoda(paired appendages).
Class-Arachnida(4 pairs of legs)
Family-Buthidae/Mesobuthidae
Genus & species-Scorpion
* Sting apparatus-
* Scorpion are fearsome arthropods in which a strong stinging apparatus is present in the last abdominal segment at the ned of their highly mobile tail.
* The sting is bilobed at the base and has a pointed spine at the apex.
* Inside the swollen part there are poison gland enclosed in muscles.
* The two poison ducts open separately at the tip of the spine.
* Venom:
* The venom is clear,colourless fluid called Toxalbumin containing toxic substances which are injected when a scorpion stings.
* The venom of scorpion is used for catching prey and defense scorpion venoms are complex mixtures of neurotoxin.
* It contains various neurotransmitter such as acetylcholine dopamine,serotonin and histamines.
* The toxic components include hyluronidase ,trypsin and acetic acid.  
* It also contains nerve blockers
* Effects:
*  The venom of the scorpion is very toxic and often lethal.
* It has an adverse effect on nervous system(medulla oblongata)it causes reverse peristalsis.
* It also affects the blood the blood pressure by the contraction of blood vessels.
* The venom has the capacity to inhibit the respiratory reflexes and circulatory reflexes.
* It increase the cardiac output causing unconsciousness,coma and ultimately death.e.g.,Centruroides(Arizona USA),Buthus,Mesobuthus sp.(India.)

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Coelentrates|Animal toxins|Immunology|Toxicology.

Posted by Mumtaz khan Saturday, 28 January 2012 0 comments

COELENTERATES
Classification:-
Phylum-Cnidaria
Class-Hydrozoa-Hydra,Sea-anemone
         Anthozoa-Corals.
         Scyphozoa-Jelly fish,Physalia.
* Sting Apparatus:
* All the coelentrates posses thousands of microscopic stinging cells or nematocysts.
* Nematocyst is a special type of cell containing venom aparatus.
* The apparatus consists of  long coiled thread,the broad base of which is called butt,which may be provided with sharply pointed barbs.
* The opening is guarded by a long stiff spine called Cnidocil.
* Normally the stinging cell is encased in a capsule but on stimulation the thread is ejected out and the poison is injected into victim.
* The nematocysts are activated by mechanical or chemical stimulation.
* Venom:
* Hypothalamus and Haemothalasins both of which are proteins are the venoms found in coelenterates.
* It also contains phospholipases,neurotoxin,nephrotoxin,Ag proteins and hyaluronidases.
* Venom differ in composition in different nematocysts.
* The protein component of venom are heat liable,degradable by proteolytic agents.
* Effects:
* The initial effect of contact with nematocysts is a kind of stinging sensation and when the toxin is injected,a shooting pain is experienced.
* The venom produces dermal reactions such as redness of skin,numbness,swelling like responses,when nematocysts are injected.
* The victim often experiences a shock and within minutes he may become unconscious.
* Persons in water are unable to reach land and hence are in great danger of drowning.
* Other symptoms are nausea,vomitting,muscle-cramps,severe pain,inability to move,backbone,loss of speech,inability to swallow etc
* The most fatal cases develops paralysis and coma.

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Honey Bee|Sting apparatus of Honey Bee|Toxicity|Immunology

Posted by Mumtaz khan Friday, 27 January 2012 0 comments

ANIMAL TOXINS

HONEY BEE
* Classification:-
Phylum-Arthropoda(paired appendages,exoskeleton)
Class-Insecta(3 pairs of legs present)
Genus-Apis(2 pairs of wings,free living).
Species-Indica(Indian bee)
             Mellifera(European bee)
             Florea(Little bee)
             Dorsata(African bee)
* Sting apparatus:
* In honey bee the ovipositors are modified to form sting and there exista a shaft or style which is penetrated into victim.
* The bulb squeezes out the poison produced by poison glands.
* There are two acid glands and an alkaline gland.The secretion of which
  are mixed in the poison saliva and then passed down into bulb.
* The sting in case of a worker bee shows presence of barbs that are absent in case of queen bee.
Hence,worker bee stings stings once in a lifetime after which it dies.
 * While queen bee can sting a number of times in its lifetime. 
* Venom: 
* Venom contains protein called mellilitin and enzymes like proteases,lipases and amylases.
* Mellilitin has antigenic properties having multiple antigenic sites sites.
* Hence it is very difficult to be consumed by macrophages.
* Because of presence of macrophages B and T Lymphocytes and also antibodies,the region where the sting is given swells up.
* If multiple stings are given by honey bees,the concentration of mellilitin is very high,person becomes unconscious.
* The toxic components include phospholipase,histamine,acetycholine,dopamine and serotonin.
* It also contains collagenase,hyluronidase etc.
* Effects:
* Ordinarily bee venom is not toxic and causes local pain and swellings.
* Allergic reaction comes when immune system is over senstitised to the venom and produces antibodies,causing release of histamines etc.
* Local reactions produce immediate pain,Edema,bleeding,vasodilation(sensation of warmth),Nausea.
* Generalized reactions produce,confluent red rash,shortness of breath,Edema in airway,tongue or uvula weakness,anxiety,confesion,chest pain.
* Sometimes internal clotting of blood takes plane in addition to hypertension.
* Tissue destruction or damage occurs with the sting.








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Nicotine|Plant toxin|Toxicology|Immunology.

Posted by Mumtaz khan Thursday, 26 January 2012 0 comments


NICOTINE:
* It is an alkaloid present in tobacco plants.
* Nicotine is mainly concentrated in tobacco leaf and this tobacco is mainly used in agricultural purpose as insecticide as well as in domestic purpose.
* Recently,tobacco was introduced as pharmaceutic product in the form of nicotine chewing gum,which helps smokers who want to quit smoking.
* It is absorbed through mucosal membrane,alveoli or skin.
* It is excreted by gastrointestinal tract,urine and small amount through respiratory tract.
* Toxicity:
* The chain smokers are nicotine dependent and therefore they become addicts to smoking.
* Nicotine acts to stimulate CNS and its action on neuro muscular junction mimics that of acetycholine.
* Nicotine poisoning results in symptoms such as salivation,vomiting,muscular weakness,convulsions,respiratory discomfort,loss of consciousness,severe irritation of mouth,esophagus and gastric mucosa.death occurs by respiratory failure
* Chronic toxicity:
Heart diseases,change in vision,deafness,nose and throat irritation,decreased ciliary action of bronchi,increase in heart beat,pulmonary emphysema i.e.,enlargement of alveoli,bronchitis,gastric ulcer,cancer of esophagus,lungs,mouth and urinary bladder.
* Diagnosis:
Odour of nicotine in breathing,burning mouth,anxiety,nausea,respiratory failure etc.
* Treatment:
Artificial respiration,infections of penta barbitone is used to warm up the body i.e.,to increase peripheral circulation.

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CAFFEINE:
* Common  source of caffeine is tea or coffee which is used as beverages.It is cultivated in India,China,Japan and Sri Lanka.
* Chemical composition:
* The principle constituent of tea is caffiene.
* It also contains traces of thiobromine which is dimethyl Xanthine.
* The tea plant also contains Xanthine or volatile oils.
* The caffeine is about 1-3% and tannin is about 10-24%.
* Now-a-days caffeine can be produced synthetically which occurs as white powder.
* It is bitter in taste,soluble in citric acid,benzoic acid,salicyclic acid or bromides.
* Uses:
Caffiene is used forobtaining effct on CNS.
The action is almost physiologic in nature and helps to remove fatigue and sleepiness.
It is also used in certain types such as neuralgia,migraine,rheumatism cardiac etc.it is also used as diuretic.
It also stimulates cardiac system.
Activation of kidney also takes place.
Caffeine treatment is given to those who suffer from depression of CNS.
* Toxicity:
Large dose of caffeine causes restlessness,insomnia,excitement and diuresis.

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Microbial Toxins|Immunology|Toxicology

Posted by Mumtaz khan Monday, 23 January 2012 0 comments

1. Problem arising from pathogenic microorganisms and their toxic metabolites in food are many.
2. They range in severity from intestinal disturbances caused by clostridium perfrigens or Staphylococcus to the highly lethal intoxication caused by ingestion of toxins produced clostridium botulinum.
 3. Modern methods of food processing have influenced the pattern of food borne infections and intoxicants.
4. Poor hygiene control of a widely distributed product can result in infection of consumers over extended period of time.
5. Inadequately pasteurized batch process eggs,used in baking industries have been found to be source of Salmonella infections over wide areas.
6. Salmonella and related Arizona infections are seen in intestinal tracts of poultry,cattle and swine which become the permanent reservoirs of the human food borne Salmonella infections.
7. The result of improper heating and cooling practices gives rise to clostridium perfrigens and Bacillus cereus infections and staphylococcal food intoxication.
8. Botulinum the intoxication resulting from the ingestion of highly lethal toxins produced by clostridium botulinum organisms is the most widely known food borne intoxicantions.
9. The actual incidence is surprisingly low in humans,but large scale outbreaks have been reported in animals.
10.Smoked and fermented fish,liver paste and even beef jerky have identified as causing botulism outbreaks.



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Mycotoxins|Immunity|Toxicology

Posted by Mumtaz khan Saturday, 21 January 2012 0 comments


1. Fungi which contaminate a wide variety of foodstuffs,especially cereals,grains also produce toxic metabolites,frequently termed mycotoxins.
2. Molds are capable of producing a variety of complex organic molecules,most of which are non-toxic.
3. Ergotism from rye infected with claviceps purpurea was probably the first mycotoxicosis to be recognized,but it has larger been eliminated as a human food problem.
4. Aflatoxins, the toxic metabolites produced by some strains of the fungus Aspergillus flavus have been widely studied in recent years,because of their known toxicity and carcinogenicity in many species of animals and because of wide distribution of fungus in foodstuffs,especially peanut meals.
5. Aflatoxicosis was first recognized in 1960 in England when serious outbreaks of the intoxication occurred in turkey,since then outbreaks have been reported in ducks,swine and young cattle.
6. Aflatoxins have been found in samples of oil seeds,pulses and other food staples from various parts of world.
7. The chronic ingestion of Aflatoxins have been a major contributing in the high incidence of human liver cancer in certain areas of southeast Asia and Africa where inhabitants consume cereals,peanuts and other foodstuffs frequently infested with molds

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RNA as a Genetic Material.

Posted by Mumtaz khan Wednesday, 18 January 2012 0 comments

       As more and more viruses were identified and studied it became clear;that many of them contain RNA and proteins,but no DNA.In all cases studied till date it is clear that these RNA viruses store their genetic information in nucleic acids rather than in proteins.Just like all other organisms Although in these viruses,the nucleic acid is RNA.
          The demonstration that RNA is genetic material in RNA containing viruses,came in 1956,when Gierer and Schram,showed that,the tobacco plants could be inoculated with purified RNA from the tobacco Mosaic Virus
(TMV) and TMV like lesions could later be identified in tobacco leaves.One of the first experiments that established RNA as genetic material in RNA viruses was the so called reconstitution experiments of Fraenkel-Conrat and singer published in 1957.Conrat and Singer's simple but definitive experiment was done with TMV. A small virus composed of single molecule of RNA,encapsulated in a protein coat.Different strains of TMV in chemical composition of their protein coats.
         By using the appropriate chemical treatments one can be separate,the protein coats of TMV from RNA.Moreover this process is reversible and by mixing the proteins and RNA under appropriate conditions reconstitution will occur giving complete infective TMV particles.Conrat and Singer took 2 different strains of TMV, separated the RNA's from their protein coat and then reconstituted mixed viruses, by mixing the proteins of one strain withthe RNA of the 2nd strain and vice versa.
When thse mixed viruses were used to infect the tobacco leaves,the phenotypically and genotypically identical to the parent strain from with the RNA had been obtained.Thus,the genetic information of TMV is stored in RNA and not in Protein.


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          Although RNA,like DNA,can store hereditary information,it is not as good a starch house of the same as DNA.Unlike DNA,RNA is essential in decoding stored information,self-replication of DNA is well known,but it is mediated by the enzyme-DNA polymerase.In other words,DNA cannot replicate without the help of well-defined protein catalysts.But there are instances of RNA molecules that self-catalyse with sequence-specific hydrolysis and transesterification reactions of RNA substrates.This findings justifies the role of RNA catalysts in the origin of life..RNA catalysis may have been crucial at any early stage in biochemical evolution.The RNA was the original self-replicating molecule that delegated to DNA the storage information capacity and to polypeptides the controllable activities.A consequence of the co-operation of the 3 kinds of macro molecules(RNA,DNA,and Protein.)is the evolution of the efficiency of self-replicating entities,the living cells.


         Crick(1968)proposed that the first form of life were essentially RNA machines.
Thus,life appeared when the period of chemical evolution was almost over atleast 4 billion years ago.It was the first stage of organic evolution.It was a RNA world.Since the RNA molecules used to adapt to new niches of enironment.The notion that life began from RNA remains very attractive.

GENES MADE OF RNA :-
         The genetic system explored by Hershey and chase was a phage-a bacterial virus(which had DNA as genetic material).
A virus particle by itself is essentially just a package of genes(can be DNA or even RNA).It has no life of its own,no metabolic activity,it is inert.But when the virus infects a host cell,it seems to come to life.Suddenly the host cell begin making viral proteins outside,but lifelike agents inside hosts,viruses resist classification.Some scientists refer to them as ''livings'' or even ''organisms''.We prefer a label that although more cumbersome is also more descriptive of a virus's less than living status;thus we will call a virus a genetic ''system''.The term applies to any entity-be it a true organism,a virus or even a bare circle of plant-infectinf RNA called a VIROID-that contains genes capable of replicating.
Most genetic systemstudied to date contain genes made of DNA.But some viruses including several phages(TMV,influenza virus,Polio virus,Rous sarcoma Virus(RSv),AIDs virus etc.)Plant nad animal viruses and all viriods have RNA genes.Sometimes viral RNA genes are double stranded but usually they are single stranded.

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Haptens and the Study of Antigenicity.|Hapten carrier

Posted by Mumtaz khan Saturday, 14 January 2012 0 comments

              The pioneering work of Karl Landsteiner in the 1920's and 1930s created a simple ,chemically defined system for studying the binding of an individual antibody antibody to a unique epitope on a complex protein antigen.Landsteiner employed various haptens,small organic molecules that are antigenic but not immunogenic hapten-carrier conjugate.Animals immunized with such a (1) The hapten determinant,(2) unalterd epitopes on the carrier protein,and(3) new epitopes formed by combined parts of both the hapten and carrier.By itself,a hapten cannot function as an immunogenic epitope.But when multiple molecules of a single hapten are coupled to a carrier(or nonimmunogenic homopolymer),the hapten becomes accesible to the immune system and can function as an immunogen.

                       The beauty of the hapten-carrier system is that it provides immunologists with a chemically defined determinant that can be subtly modified by chemical structures on immune  specificity.In his studies,Landsteiner immunized rabbits with a hapten-carrier conjugate and then tested the reactivity of the rabbit's immune sera with that hapten and with closely related haptens coupled to a different carrier protein.He was thus able to measure,specifically,the reaction of the antihapten antibodies in the immune serum and not of antibodies to the original carrier epitopes.Landsteiner tasted whether an antihapten antibody could bind to other haptens having a slightly different chemical structure.If a reaction occurred,it was called a cross-reaction,Landsteiner was able to gain insight into the specificity of antigen-antibody interactions.
                  Using various derivatives of aminobenzene as haptens,Landsteiner found that the overall configuration of a hapten plays a major role in determining whether it can react with a given antibody.For example,antiserum from rabbits immunized with aminobenzene or one of its carboxyl derivatives(o-aminobenzoic acid, m-aminobenzoic acid, p-aminobenzoic acid) coupled to a carrier protein reacted only with the original immunizing hapten and did not cross-react with any other haptens.In contrast,if the overall configuation of the hapten was modified in the para position with various non-ionic derivatives ,then the antisera showed various degrees of cross-reactivity.Landsteiner's work not only demonstrated the specificity of the immune system,but also demonstrated the enormous diversity of epitopes that the immune system is capable of recognizing.
              Many biologically important substances,including drugs,peptide hormones and steroid hormones,can function as haptens.Conjugates of these haptens with large protein carriers can be used to produce hapten-specific antibodies.These antibodies are useful for measuring the presence of various substances in the body.For instance,the original home pregnancy test kit employed antihapten antibodies to determine whether a womens urine contained human chorionic gonadotrophin(HCG), which is a sign of pregnancy.However,as shown in the clinical Focus,the formation of drug-protein conjugates in the body can produce drug allergies that may be life-threatening.

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What are Enzymes|Co-Enzymes|Regulatory Enzymes|Protein.

Posted by Mumtaz khan Saturday, 7 January 2012 0 comments

Enzymes:
         One of the most unique characters of a living cells is its ability to allow complex reactions to proceed rapidly at the temperature of the surrounding.The principle agents which participate in these transformation belong to a group of proteins called ''Enzymes''. Enzymes are biological catalyst.They increase the rate of chemical reactions by taking place within living cells without themselves undergoing any change.The reactants of enzyme catalyzed reactions are called as substrate and each enzymes is quite specific in character.
          All enzymes are proteins.However most of the enzymes have a non-protein component called co-factor.Without this co-factor these enzymes lack their catalytic activity activity. In such as a case,the inactive protein component is called as 'Apoenzyme' and active enzyme including the co-factor is called as 'Holoenzyme''. The co-factor may be an organic molecule called co-enzyme or it may be a metal ion.Some enzymes bind the co-factors very tightly without damaging the enzymes.Such a co-factor is called as prosthetic group.
           The polypeptide or protein part of the enzyme is called the apoenzyme and may be inactive in its original synthesized structure. The inactive form of the apoenzyme is known as a proenzyme or zymogen. The proenzyme may contain several extra amino acids in the protein which are removed, and allows the final specific tertiary structure to be formed before it is activated as an apoenzyme.


Co-enzymes:-
Co-enzyme is a small heat stable organic molecule readily dissociates off an enzyme protein and in fact can be dialised from protein.
A co-enzyme has an important relationship with vitamins play an essential role,because most of co-enzyme show a vitamin as a part of their structure.
There are also organic molecules of small size compared to the enzymatic protein.
These molecules are called co-enzymes for historical reasons.They remained firmly bound to the enzymatic protein throughout the purification procedure.
This designation is extremely misleading.There are two broad categories of co-enzymes.The first category which really deserve to be called co-enzyme,includes the co-enzymes which are really part of active site.In other words,the small co-enzyme organic molecules assists the protein side chains in catalysis.The best example of such a co-enzyme is pyridoxal phosphate.
The second category of molecule called co-enzymes does not really deserve its name.it would be preferably to call themselves substrates.The prototype of this type of co-enzyme is NAD.

 Regulatory enzymes:
 A regulatory enzyme is an enzyme in a biochemical pathway which, through its responses to the presence of certain other biomolecules, regulates the pathway's activity. This is usually done for pathways whose products may be needed in different amounts at different times, such as hormone production. Regulatory enzymes exist at high concentrations (low Vmax) so its activity can be increased or decreased with changes in substrate concentrations.
Regulatory enzymes are of two types:
1. Allosteric enzymes
2. Covalently modulated enzymes.
The allosteric enzymes has two binding sites. One of the binding sites is for the substrate of the enzyme, the other site is for small molecules called effectors which modulates the enzymes activity.effectors are non-covalently linked to the enzyme at its allosteric site (site of enzyme where the effector binds) and its interaction with the enzyme is reversible. Based on modulation, allosteric enzymes can be grouped into two groups:
1.homotropic allosteric enzymes.
2.heterotropic allosteric enzymes.






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Classification of Enzymes|Enzyme classification|Enzyme

Posted by Mumtaz khan Sunday, 1 January 2012 0 comments


The six major classes of enzymes are:

1.Oxido-reductases:
This class includes enzymes which were earlier called as Dehydrogenase.They bring about oxidation reduction reaction between two substrates S,S'.
       More precisely, these enzymes Catalyse electron transfer reactions. In this class are included enzymes catalyzing oxido-reductions of CH-OH,C=O,CH-CH,CH-NH2,CH-NH groups.Accordingly they are numbered as 1.1,1.2,1.3,1.4,1.5.

1.1 : Acting on CH-OH group(Alcohol):
1.1.1-With NAd or NADP as hydrogen acceptor.
Ex. L-Malate : NAD-oxido reductase

1.1.2-With a cytochrome as acceptor.
Ex. L-Lactate : ferricytochrome C -oxido reductase.

1.1.3-With Oxygen as hydrogen acceptor.
Ex. glucose oxidase or beta-D-glucose : oxygen-oxido-reductase.

1.2 :Acting on a C=O group (aldehyde or ketone):
1.2.1- With NAD or NADP as acceptor.
Ex.  D-glyceraldehyde-3-phosphate : NAD oxido-reductase.

1.2.3-With oxygen as aceptor
Ex. Xanthine oxygen oxido reductase.

1.3 : Acting on CH-CH group:
1.3.1 -With NAD or NADP as acceptor.
Ex. 4.5 dihydrouracil : NAD oxido reductase.

1.3.2-With a cytochrome as acceptor.

1.3.3-With Oxygen as acceptor
Ex. 4.5-dihydro-orotate : Oxygen oxidi reductase.

1.4 : Acting on CH-NH group(amidos):
1.4.1-With NAD or NADP as acceptor.
Ex. L-glutamate : NAD oxido-reductase.

Transferases:
Enzymes which catalyse the transfer of a group G other than hydrogen between a pair of substrates S and S' are called transferases.
         In these are included the enzymes catalisng the transfer of one carbon group aldehydic or ketonic residue,acyl,glycocyl,alkyl,phosphorous or sulphur containing groups.They are numbered as 2.1,2.2,2.3,2.4,2.5,2.6,2.7,..

2.1 : Transferring a monocarbon group.
2.1.1- Methyl transferase.
Ex . S- adenosyl-methionine : L-homocysteine S-methyl transferase.

2.1.2- Hydroxymethyl transferases and formyl transferases.
Ex. L-serine : tetrahydrofoliate 5,10 hydroxymethyl transferase.

2.1.3: Carboxyl transferases and Carbamyl transferases.
Ex. Carbamyl phosphate : L aspartate Carbamyl transferase.

2.3 : Acyl transferases

2.4 : Glycosyl transferases

2.4.1-Hexocyl transferases
Ex. UDPG-glucose : D-fructose glucocyl transferase.

2.4.2-Pentosyl transferases
Ex. Uridine : Orthophosphate ribosyl transferase.

2.5 : Alkyl transferases

2.6 : Transferring nitrogen groups.
2.6.1- Amino transferases
Ex. L-aspartest : Ketoglutarate aminotransferase.

2.7 : Phosphoryl transferases
2.7.1- With an alcohol group as acceptor
Ex. ATP : D-hexose-6-phosphotransferase.

2.7.2-With a Carboxylic group as acceptor.
Ex. ATP : 3 phosphoglycerate 1-phosphotransferase

2.7.3-With a nitrogen group as acceptor.
Ex.Atp: creatine phosphotransferase.

Hydrolases:
These enzymes catalyze the hydrolysis of the substrates  by adding constituents of water across the bond they spilt.The substrate include esters,glycosides: glycosyl compounds,ethers,peptides,acid anhydrides, C-C halides and P-N bonds.
        They are correspondingly numbered as 3.1,3.2,3.3,3.4,3.5,3.6,3.7,3.8,...

3.1 : Splitting the ester bonds
3.1.1- Carboxylester-hydrolases.
Ex. Lipase or glycerol-ester hydrolase.

3.1.3-Phosphomonoesterase
Ex. alkaline phosphate.

3.1.4-phospho diesterases
Ex. Alkaline phosphatases

3.2 : Splitting oside bonds
3.2.1-glucosidases
Ex. beta-glucosidase or beta-D-glucoside glucohydrolase.

3.4 : Splitting peptide bonds.
3.4.1-alpha-aminopeptido-amino acid hydrolases.
Ex.aminopeptidase or aminoacyl-peptide hydrolase.

3.4.2- alpha-carboxypeptido-amino acid hydrolases.
Ex. carboxypeptidase A or peptidyl-L-aminoacid hydrolase.

3.4.4-Peptido-peptide hydrolases(endopeptidases).
Ex. Trypsin.

Lyases(Desmolases):
These are enzymes which catalyze the remol of groups from substrates by mechanism other than hydrolysis leaving double bonds.
        In these,the enzymes included are those which act on C-C,C=O,C-N,C-S,C-halide bonds.
Accordingly they are numbered as 4.1,4.2,4.3,4.4,4.5,..

4.1 : C-C Lyases.
4.1.1 -Carboxylases(Carboxylases or decarboxylases).
Ex .aspartate decarboxylase or L-aspartate 4,Carboxylase.

4.1.2-Aldehyde-lyases.
Ex. fructose-biphosphate aldolase or fructose1-6 biphosphate : D-glyceraldehyde-3-phosphate lyase.

4.2 : C-O lyases.

4.3 : C-N Lyases

4.3.1 Ammonia lyases.
Ex. L-aspartate-ammonium lyase.

Isomerases:
They catalyze interconversion of optical-geometic or positional isomers by intra-molecular rearrangement of atoms or groups.
Ex. Racemases and Epimerases.
Trans-Isomerase,intramolecular oxidase etc.

5.1 : Racemases and Epimerases
5.1.1-Acting on amino acids
Ex. alanine racemase

5.1.3-Acting on oses
Ex. D-ribulose-5-phosphate-3-epimerase

5.2 : Cis-trans isomerases
Ex. 4 malelyl-aceto acetate cis-trans isomerase.

5.3 : Intramolecular Oxidoreductases.
5.3.1 - Catalizing the interconversion aldose-ketose.
Ex. D-glyceraldehyde 3-phosphate keto-isomerase or triosephosphate isomerase.

5.4 : Intramolecular transferases.
Ex. L-methylmalonyl-CoA-carbonyl mutase.

Ligases or synthetases:
They catalyze linking of two compounds using energy from ATP or a similar energy compound.This category includes catalyzing reactions forming C-O,C-S,C-N Nd C-C bonds.
Accordingly they are numbered as 6.1,6.2,6.3,6.4,... 


6.1 :Formation of C-O bonds.
6.1.1-Amino acyl-tRNA synthetase(or amino acid tRNA ligases)
Ex.Alanyl-tRNA synthetase.

6.2 : Formation of C-N bonds.
   
6.3 : Formation of C-N bonds.
6.3.1-Acid-ammonia ligases.
Ex. L-glutamate : ammonia ligase or glutamine synthetase.

6.3.2-Acid amino acid ligases.
Ex. Y-L-glutamyl-L-cysteine : glycine ligase or glutathione synthetase.

6.4 : Formation of C-C bonds.


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NOMENCLATURE OF ENZYMES:
     
       With the continuous increase in the knowledge of enzymology ,various system have evolved to name and classify the enzyme using various criteria as the basis.Some enzymes are named with any significance e.g.,Diastase,trypsin,pepsin,renin etc.
Enzymes were named depending upon:
     * Substrate they acted upon.
     * Type of reaction catalyzed.
     * Substrate that is synthesized.
     * Chemical composition of the enzyme.
     * Substance hydrolyzed and the group involved
Overall chemical reaction taken in consideration.In 1961,International Union of Biochemistry(IUB)used the overall chemical reaction as a criteria for classification and nomenclature of enzymes.Although the complicated IUB system is precise,descriptive and informative.The major features of this system of classification is as follows:
     * The reactions and the enzymes catalyzing them are divided into 6 major classes each with 4-13 sub   classes
     * Each enzymes name has two parts viz.,(i)The first pat is the name of the substrate/s. (ii)The second part which ends in the suffix 'ase' indicates the type of reaction catalyzed .
     * Additional information regarding the nature of reaction if needed is given in parenthesis.
     * Each enzyme has been allotted a systematic code number called as 'Enzyme commission number or E.C. number.The enzyme commission number for each enzyme consist of series of number at 3 places.The first place number representing the major class to which the enzyme belongs.The median number indicating/denoting the sub class and sub-subclass within the major class.The last place of the four digit represents the serial number of the enzyme with the sub-sub class.

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