Microbiology Procedure

Index >> Enzymes,Isozymes and Coenzymes >> ISOZYMES

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Enzymes,Isozymes and Coenzymes Nomenclature of Enzymes Oxidoreductases Transferases HydSrolases Lyases Isomerases Ligase - Synthetases Enzymes and their Functions Structure of Enzymes Active Site of Enzymes Specificity of Enzymes Activation Energy of Enzymes Effect of Temperature on Enzyme Activity

ISOZYMES

	ISOZYMES - Enzymes having similar biological action may be isolated from different sources. Thus many different molecular species of an enzyme have the same function. Such enzymes which exist in more than one form are called isozymes. More than a hundred enzymes are known to exist as isozymes.
When the variants of an enzyme are within the same species of an organism they are called intra specific or ontogenetic variants. When they are from different species they are called inter specific or phylogenetic variants. Multiple forms of the same enzyme may also be found in the same organism. In humans there are three different types of haemoglobin, two in the adult and one in the foetus.
These are formed by the union of four polypeptide chains. The enzyme lactic dehydrogenase (LDH) is present in most animal tissues as five isozymes. It has two subunits or monomers, the H (heart) polypeptide and the M (muscle) polypeptide. Heart and muscle LDH have different amino acid compositions and different properties. Four units, in different combinations, make up the five different molecular forms of LDH. The five isozymes are. 1. HHHH or H4 2. HHHM or H3M 3. HHMM or H2M2 4. HMMM or HM3 5. MMMM or M4

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Effect of Enzyme Concentration Inhibition of Enzymes Control of Enzyme Action ISOZYMES COENZYMES - COFACTORS Coenzymes and their Vitamin Precursors

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