The active center of the enzyme.

is a biological large molecule, the enzyme as
protein
, its molecular volume is much larger than the substrate molecule volume. When the enzyme is in contact with the substrate during the reaction, it is limited to a small group or smaller part of the enzyme molecule. The enzyme molecule binds directly to the substrate and catalyzes the site where the substrate
bio-chemical
reacts, called the active center of the enzyme (active site ).
. Physically, the active center is often a dent in the enzyme molecule surface, and structurally, if it is simply
protease
, the active center is usually made up of several
amino acids
polar groups
on the residual side chain of the enzyme molecule. The amino acids that make up the active center of the enzyme are tyrosine (Asp ), glutamate (Glu ), serine (Ser ), histamine (His ), Cysteine (Cys ), lysine (Lys ) and so on, their side chains contain arginine, hydroxy , methane, , amino and other polar groups. If these groups are chemically modified, such as oxidation, reduction, alamization, alkalization, etc., the activity of the enzyme is lost, and these groups are called essential groups. For binding proteases that require cofactors, coenzyme (or co-base) molecules or a portion of their molecular structure are often also part of the active center.
. Several amino acids that make up the center of enzyme activity, although not closely adjacent in the first-level structure, may be far apart, and may even be on different peptide chains, but because the folding and coiling of peptide chains make them close to each other in the spatial structure, forming a certain spatial structure located on the surface of the enzyme molecules, cracked small areas.
. The base group of the active center is required, but the essential group also includes those that are necessary to maintain the spatial composition of the enzyme outside the active center. Therefore, the role of other parts of enzyme molecules may be secondary to enzyme catalysis, but it is by no means meaningless, and they at least provide a structural basis for the formation of enzyme activity centers. Therefore, the relationship between the active center of enzyme and the spatial image integrity of enzyme protein is dialectical unity. When enzymes are present in a catalyticly active structure, the active center is naturally formed. Once the external physical and chemical factors destroy the composition of the enzyme, peptide chain stretching, the specific structure of the active center disintegrates, the enzyme loses the ability to react with the catalytic substrate, the result is enzyme degeneration inactive. Table4-2amino acid residues of some enzyme activity centers.
. The catalytic capacity of enzymes is limited to a certain area of the large molecule. A side-chain group of enzyme molecules directly involved in the remnants of amino acids that bind to the substrate and catalytic action is based on a region of spatial structure, called the active center of the enzyme (active center ) or the active site (active site ). For binding enzymes, a part of the structure of a coenzyme or co-base molecule is also part of the active center. The active part of the enzyme is the structural basis for the enzyme to perform catalytic function. The side chains of the amino acid residues that make up the enzyme activity center may be very far apart in the first structure and may even be located on different peptide chains, folded around the peptide chains, and are close to each other in the spatial composition to form an active area in the appropriate position. This area is located in a crack in the surface of the enzyme molecule( crevice).. The active center of the enzyme consists of two functional parts: one is the binding site, which is the base group in which the enzyme binds to the substrate, which determines the specificity of the enzyme, and the other is the catalytic site, the base group where the sensitive bonds of the catalytic substrate change chemically, which determines the catalytic capacity of the enzyme. But these two parts do not exist independently of each other, forming the relevant groups of these two functional parts, sometimes at the same time combining the substrate and catalytic substrate reaction function. The base group of the enzyme activity center belongs to the necessary group, but the base group also includes the base group other than the active center, which is necessary for the enzyme to express vitality, such as Serhydroxyl, Cysbase, Hismide, etc., they do not bind to the substrate, or directly participate in the reaction that causes the intermediate product decomposition, but only to maintain the spatial composition of the enzyme molecule..