ENZYME

Enzim as Catalyst

Various kind of protein molecules known as enzyme serve to accelerate, or catalyze, the chemical reactions of living cell. Without enzyme, most biochemical reactions would proceed to slowly to effectively carry on life processes.

The manufacture of these enzymes is regulated by the cell’s genetic material, deoxyribonucleic acid (DNA) through the process of protein synthesis. The potential of a cell to grow and divide is determined largely by the number and different kinds of enzyme it contains. Certain cell also perform specialized function, such as transmitting nerve impulses or producing hormones, that are regulated by enzyme. Several hundred different reaction may proceed simultaneously within a cell, each one catalyzed by one or more enzymes.

Enzymes differ from in organic catalysts, such as platinum and palladium, in two important ways; the sequence of amino acid in an enzyme molecule is specific that enzyme and essential for the molecule’s catalytic action only on specific substance in specific reaction. A nonbiological catalyst, by contrast, catalyzes, a wide variety of chemical reactions.

Catalysis of Reaction

The defining property of all catalysts is that they increase the speed of chemical reaction without being used up or appearing as one of the product of the reactions.

Before the end of the 19th century, chemist understood that molecule must obtain extra energy before they can interact. The extra energy, or energy of activation, may be supplied when one molecule collides with another, or it may be supplied by an external source of energy, such as heat or ultraviolet radiation. The primary barrier to interaction , therefore, is the energy of activation, which is some times called the energy barrier.

The Higher the energy barrier, the fewer the molecules that will pass over it, and thus the slower the rate of reaction.

In 1889 the Swedish chemist Svante Arrhenius suggested that a catalyst (C) acts as follow ; it first forms intermediate compound (CS) with the reactant, or substrate (S) . The compound (C) then enters a so called transition state, which presents a lower energy barrier to chemical reactions; finally (CS) decomposes into (C)catalyst, whish is unchanged, and the product, of the raction again and again.

If the word catalyst is replace by the word enzyme (E), the fundamental equation of enzyme catalyst is:

E + S ó ES -> E + P

This equations is often called the Michaelis-menton equation. And ES is called the Enzyme-substrat complex, enzyme reduce the activation energy, or energy barrier, for a biochemical reaction . Enzyme are far more effective then inorganic catalyst in reducing activation energies; thus, they permit biochemical processes to take place at temperatures compatible with life.