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Chapter-06 Enzymes

BOOK TITLE: Biochemistry

Author
1. Naik Pankaja
ISBN
9788184487077
DOI
10.5005/jp/books/11094_6
Edition
3/e
Publishing Year
2010
Pages
34
Author Affiliations
1. NDMVPS Medical College, Nashik, Maharashtra, India, MVPS Dr Vasantrao Pawar Medical College, Nashik, Maharashtra, India, SMBT Institute of Medical Sciences and Research Center, Nashik, Maharashtra, India
Chapter keywords

Abstract

Enzymes are proteins that act as biocatalyst. Zymogens are inactive precursor of enzymes. Coenzymes are non-protein component enzymes required for its optimum activity. Many vitamins are precursors of coenzymes. Enzymes are classified into main 6 classes according to the type of reaction it catalyzes viz. oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases. Enzymes are highly specific both in the reaction catalyzed and in the choice of substrate. The rate of enzyme catalyzed reaction is dependant on substrate concentration and can be represented mathematically by Michaelis Menten equation. Enzyme kinetics is an important method for the study of enzyme mechanism. The Michaelis Menten constant (Km) is the substrate concentration at the half maximum velocity (Vmax/2). Enzymes can be inhibited reversibly or irreversibly by specific molecules. Many clinically important drugs are enzyme inhibitors. Enzyme activity can be regulated by allosteric enzyme. Allosteric enzymes have one or more regulatory sites for binding modulators. Isoenzymes are multiple forms of the same enzymes, e.g. lactate dehydrogenase and Creatine Kinase. Separation and identification of enzymes is of diagnostic value. Measurement of enzymes in plasma is used clinically for the investigation of diseases of liver, cardiac, skeletal muscle, biliary tract and the pancreas. Enzymes are also used in the treatment of diseases of human being, e.g. streptokinase, asparaginase, etc.

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