Definition And Characteristics of Enzymes
Enzymes are protein catalyst produced by a cell and responsible ‘for the high rate’ and specificity of one or more intracellular or extracellular biochemical reactions. Enzymes are biological catalysts responsible for supporting almost all of the chemical reactions that maintain animal homeostasis. Enzyme reactions are always reversible. The substance, upon which an enzyme acts, is called as substrate. Enzymes are involved in conversion of substrate into product. Almost all enzymes are globular proteins consisting either of a single polypeptide or of two or more polypeptides held together (in quaternary structure) by non-covalent bonds. Enzymes do nothing but speed up the rates at which the equilibrium positions of reversible reactions are attained. In terms of thermodynamics, enzymes reduce the activation energies of reactions, enabling them to occur much more readily at low temperatures – essential for biological systems. The basic characteristics of enzymes includes
(i) Almost all the enzymes are proteins and they follow the physical and chemical reactions of proteins
(ii) Enzymes are sensitive and labile to heat
(iii) Enzymes are water soluble
(iv) Enzymes could be precipitated by protein precipitating agents such as ammonium sulfate and trichloroacetic acid.
Intext Quections
1. Enzymes are …………… biocatalyst produced by cells.
2. Enzymes follow physical and chemical properties of ……………
3. Enzymes are …………… soluble.
(a) Water (b) acid (c) organic acids
4. Precipitation of enzymes could be achieved by using ………….. and …………..
