Metabolism and Energy Transformation in Body Cells - Renata Armenakovna Petrosova 2004

Enzymatic nature of metabolic reactions
Properties of enzymes

One of the most crucial differences between Enzymes and inorganic catalysts is their high substrate Specificity. A defining characteristic of biocatalysts is their ability to accelerate reactions involving only a specific substrate or a group of structurally similar substrates. Investigating this remarkable selectivity of enzymes, the German scientist E. Fischer hypothesized the existence of a specific site within the enzyme molecule whose Structure strictly complements that of the substrate. His famous analogy—that “the substrate fits the enzyme like a key in a lock”—captured one of the most essential Properties of Enzymes: substrate specificity.

For instance, the Human and Animal body lacks the enzyme required to digest Cellulose, yet starch and Glycogen are readily hydrolyzed by the enzyme amylase. The structural difference between these CARBOHYDRATES lies solely in the fact that the first molecule is composed of β-glucose residues, whereas the other two consist of α-glucose residues. The enzyme amylase targets the α-glycosidic bond in molecules of starch, glycogen, and maltose, but has no effect on the β-glycosidic bond found in cellulose.

The enzyme Trypsin hydrolyzes both natural Proteins and synthetic Polypeptides because it acts upon the peptide bond. Such enzymes exhibit group specificity, as they catalyze reactions involving substances that share a common type of chemical bond.

Nevertheless, certain enzymes catalyze reactions involving only a single, specific substance.