What are enzymes ? Write in brief the mechanism of enzyme catalysis.
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Enzymes are macromolecularbiological catalysts. Enzymes accelerate chemical reactions. The molecules upon which enzymes may act are called substratesand the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the cellneed enzyme catalysis in order to occur at rates fast enough to sustain life.Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called enzymology and a new field of pseudoenzyme analysis has recently grown up, recognising that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties.Enzymes are known to catalyze more than 5,000 biochemical reaction types. Most enzymes are proteins, although a few are catalytic RNA molecules. The latter are called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures.
Like all catalysts, enzymes increase the reaction rate by lowering its activation energy. Some enzymes can make their conversion of substrate to product occur many millions of times faster. An extreme example is orotidine -phosphate decarboxylase, which allows a reaction that would otherwise take millions of years to occur in milliseconds.Chemically, enzymes are like any catalyst and are not consumed in chemical reactions, nor do they alter the equilibrium of a reaction. Enzymes differ from most other catalysts by being much more specific. Enzyme activity can be affected by other molecules: inhibitorsare molecules that decrease enzyme activity, and activators are molecules that increase activity. Many therapeutic drugs and poisonsare enzyme inhibitors. An enzyme's activity decreases markedly outside its optimal temperature and pH.
Like all catalysts, enzymes increase the reaction rate by lowering its activation energy. Some enzymes can make their conversion of substrate to product occur many millions of times faster. An extreme example is orotidine -phosphate decarboxylase, which allows a reaction that would otherwise take millions of years to occur in milliseconds.Chemically, enzymes are like any catalyst and are not consumed in chemical reactions, nor do they alter the equilibrium of a reaction. Enzymes differ from most other catalysts by being much more specific. Enzyme activity can be affected by other molecules: inhibitorsare molecules that decrease enzyme activity, and activators are molecules that increase activity. Many therapeutic drugs and poisonsare enzyme inhibitors. An enzyme's activity decreases markedly outside its optimal temperature and pH.
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Answer:
Protein molecules of high molecular masses are termed as enzymes. Colloidal solutions are formed when these are dissolved in water. These are complex, nitrogenous organic compounds produced by living plants and animals. Enzymes are also called ‘biochemical catalysts’.
Mechanism of enzyme catalysis:
Various cavities are present with characteristic shapes, on the surface of the enzymes. Such cavities possess active groups such as –NH2, −COOH, etc. Complementary shape of the reactant molecules fit into the cavities just like a key fits into a lock. Activated complexes are formed due to this. This complex then decomposes to give the product.
Hence,
Step 1: E + S → ES+
(Activated complex)
Step 2: ES+ → E + P
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