Fundamentals of Biochemistry - Filippovich, Y. B. 1999

Enzymes
General concept of enzymes

As already noted, a crucial property of many Proteins is their catalytic activity, which is intimately connected with the Selection/11.html">General features of their Structure.

Catalytically active proteins are called Enzymes (from the Latin fermentum, meaning leaven) or enzymes (from the Greek en, meaning in, and zyme, meaning leaven). As THE ORIGIN OF these terms implies, the first insights into their existence came from The Study of Fermentation processes.

The Role of enzymes in the vital activity of animals, plants, and microorganisms is colossal. Through their catalytic function, A wide variety of enzymes ensure the rapid occurrence of a vast number of Chemical Reactions within the Organism or outside it. Integrating into a unified ensemble of self-regulating biochemical processes, these material-transformation reactions form the material and energetic basis for the continuous self-renewal of protein bodies—the very essence of life phenomena. Therefore, enzymes are "the agents of all chemical transformations" (I.P. Pavlov) and transducers (sensors) in the REGULATION OF METABOLISM.

Currently, several thousand individual enzymes have been discovered in biological objects, and several hundred of these have been isolated and studied. It is estimated that a living Cell may contain up to 1,000 different enzymes, each accelerating a specific chemical reaction.

Biological catalysts (enzymes) differ sharply in A number of respects from inorganic catalysts, although both merely accelerate the attainment of equilibrium in chemical processes that would occur on their own, albeit at very slow rates. Like inorganic catalysts, biocatalysts do not initiate chemical reactions; they merely accelerate existing ones. The first difference is that, compared to inorganic catalysts, enzymes "operate" under very mild conditions (low Temperature, normal pressure, moderate pH values, etc.) and with extremely high intensity. For example, the hydrolytic breakdown of protein into Amino Acids in the presence of inorganic catalysts (strong acids or alkalis) takes place at temperatures of 100° C and above over the course of several tens of hours. The same process, under the catalytic influence of specific enzymes, proceeds in tens of minutes at 30—40° C. As J. Berzelius pointed out as early as 1836, hydrolyzing starch by heating it in an acid solution requires several hours, whereas with the appropriate enzyme, the process takes only a few minutes at room temperature. Fe ions catalytically accelerate the decomposition of H₂O₂ into H₂O and O₂. However, the same Fe atoms, when part of the enzyme catalase, act 10 billion times more vigorously, and a mere 1 mg of Fe incorporated into the enzyme can replace 10 tons of inorganic Fe in this reaction. Thus, exceptional catalytic activity under conditions of normal temperature and pressure distinguishes biocatalysts from inorganic catalysts.

The second difference is that enzymes possess an unusually high Specificity of action, which is not observed in inorganic catalysts. As a rule, each enzyme catalytically accelerates a single chemical reaction or, at most, a group of Reactions of the same type.

Finally, a number of differences between biocatalysts and inorganic catalysts stem from the protein nature of enzymes. These include thermolability, the dependence of activity on ambient pH and the presence of activators or inhibitors, and others.

The most fundamental difference between enzymes and conventional catalysts has only been uncovered in recent years. It lies in the fact that, thanks to the unique structure of each enzyme, The process of Enzymatic Catalysis unfolds as a series of elementary transformations of matter that are strictly organized in space and time. Cooperativity and rigidly programmed stages of action are what distinguish The Mechanism of biocatalysis from the action of Other types of catalysts, although this does not preclude a certain degree of Variability in both The structure of the enzyme itself and the constitution of reaction intermediates during enzymatic catalysis.

In nature, under the catalytic influence of enzymes, processes such as Hydrolysis, phosphorolysis, The transfer of various groups (methyl radicals, phosphoric acid residues, etc.), Oxidation and reduction, Cleavage and synthesis, isomerization, and the like take place. Virtually all chemical transformations in living matter occur with the help of enzymes. It is therefore natural that the catalytic function of enzymes lies at The Heart of the vital activity of any organism. Through enzymes, The Influence of both internal genetic factors and external environmental factors on the organism's development is realized. Contact between enzymes and medicinal substances or Antibiotics brings about changes in enzymatic processes that contribute to the cure of diseases; conversely, changes in enzymatic activity under the influence of microbial toxins and other poisons lead to the death of the organism. The stimulation of animal and plant growth by various agricultural preparations is based in most cases on their effect on Biosynthesis or The activity of specific enzymes. Minute structural differences in certain enzymes determine the species characteristics of organisms, and disruptions in The biosynthesis of some of these enzymes underlie hereditary and other disorders. All of this highlights the immense significance of enzymes for biology, agriculture, and medicine.

Once isolated from the organism, enzymes do not lose their ability to perform their catalytic function. This forms The basis of their Practical Application in the chemical, food, light, and pharmaceutical industries. Enzyme Specificity is of particular importance for chemical manufacturing: up to 80% of the costs in producing many chemicals stem from separating impurities generated by Side Reactions. Performing synthesis using a highly specific enzyme that accelerates only the reaction leading to the desired product simplifies the technological process. Furthermore, enzymes make it possible to carry out a number of processes whose execution by conventional Methods of organic synthesis remains an unsolved problem. This is the case, for example, in The production of pharmaceutical preparations via the enzymatic transformation of Steroids.