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How do hydrolases use water to split substrates?
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Enzyme
In the induced-fit theory of enzyme-substrate binding, a substrate approaches the surface of an enzyme (step 1 in box A, B, C) and causes a change in the enzyme shape that results in the correct alignment of the catalytic groups (triangles A and B; circles C and D represent substrate-binding groups on the enzyme that are essential for catalytic activity). The catalytic groups react with the substrate to form products (step 2). The products then separate from the enzyme, freeing it to repeat the sequence (step 3). Boxes D and E represent examples of molecules that are too large or too small for proper catalytic alignment. Boxes F and G demonstrate binding of an inhibitor molecule (I and I′) to an allosteric site, thereby preventing interaction of the enzyme with the substrate. Box H illustrates binding of an allosteric activator (X), a nonsubstrate molecule capable of reacting with the enzyme.
Hydrolases are a class of enzymes that catalyze hydrolysis, a chemical process where water is used to split complex substrates into simpler molecules.
In this reaction, water acts as a reactant. The process typically involves the following steps:
- Bond Formation: A covalent bond forms between the oxygen atom of a water molecule and a specific atom (often carbon) within the substrate molecule.
- Bond Cleavage: The original bond within the substrate is broken.
- Hydrogen Transfer: Hydrogen ions from the original water molecule detach and attach to the newly formed product molecules, effectively splitting the substrate into two or more components, such as converting proteins into amino acids or fats into fatty acids and glycerol.1
By facilitating these reactions, hydrolases allow biological systems to break down complex compounds into forms that organisms can assimilate, a fundamental aspect of digestion.1