What is the chemical nature of the enzyme?
The difference between the enzyme and the general protein is that the enzyme is a protein with a special catalytic function. Similarly, the enzyme, like other proteins, consists mainly of amino acids, with one, two, three and quaternary structures, and the same enzyme as other proteins The composition of the enzyme can be divided into two types: simple protein and binding protein. Some enzymes are only protein, its activity depends on its protein structure, such enzymes are simple protein; other enzyme active ingredients in addition to containing protein, but also There are some small molecules that cofactor, the two together to be active, such enzymes belong to the binding protein.The protein part of the protein is called the enzyme protein, non-protein part called the cofactor
Enzyme is an amphoteric electrolyte, soluble in water, easy to precipitate at the isoelectric point, the enzyme activity-pH curve and the zwitterion of the enzyme. The enzyme is a high-molecular colloidal material, generally can not pass through the semipermeable membrane; Dissociation curve similar to the enzyme in the electric field can be the same as other proteins swimming; ③ lead to protein denaturation factors, such as ultraviolet, heat, surfactant, heavy metals, protein precipitants, etc., can make the enzyme failure; Protease hydrolysis and loss of activity.In addition, the most direct evidence is that all has been highly purified and crystallized enzyme for a primary structure analysis, the results indicate that the enzyme is a protein.
Enzyme protein and cofactor are present in the absence of catalytic activity, only these two parts together to form a complex to show the catalytic activity of this complex called the whole enzyme. Some enzymes cofactor is the metal ion, some enzyme cofactor is Organic small molecules in these organic small molecules, where the enzyme and protein binding is called the auxiliary base; and with the enzyme protein binding was more relaxed, dialysis can be used to separate the enzyme protein is called coenzyme. There is no strict boundary between the base and the coenzyme, the role of the metal ion in the enzyme molecule, or as a component of the active site of the enzyme, or the conformation necessary to form the center of the enzyme, or between the enzyme and the substrate The same coenzyme is often able to bind to a variety of different enzyme proteins, the composition of a variety of catalytic functions of different enzymes, such as coenzyme Ⅰ (NAD +) can be a variety of enzymes, As a coenzyme for many dehydrogenases, but each enzyme protein can only bind to a specific coenzyme into a whole enzyme.It can be seen that the specificity of the enzyme is the enzyme protein part of the coenzyme in the enzymatic reaction is usually responsible for electrons, atoms Or some chemical groups to determine the nature of the reaction.In recent years, it has been found that, in addition to proteins, some RNA and DNA molecules also have a catalytic effect on the chemical nature of the enzyme is the concept of protein produced a strong impact . However, the now known enzymes are essentially protein-based, or protein-dominated core components, and the concept that the enzyme is a protein-based biocatalyst does not exclude the presence of other types of catalysts, and more precisely, Can be given to the enzyme under the definition of: the enzyme is a kind of biological activity and special space conformation of biological macromolecules, including protein and nucleic acid.
