Several amino acid side chains comprise the active site . Coenzymes are small organic molecules, derived from vitamins, that participate in the chemical reactions catalyzed by many enzymes. Transfer Tetrahydrofolate Folate One-Carbon Group Transfer Thiamine Pyrophosphate Thiamine Aldehyde Transfer Summary of factors responsible for the rate enhancement seen with enzyme catalysis Uncatalyzed reactions in solution can be slow because They involve the formation of unstable positive and negative charges in the transition state. They frequently require several molecules to be brought together with a concomitant loss of entropy. These difficulties are lessened with enzymes because Strategically placed acids, bases, metal ions, or dipoles that are part of the structure of the enzyme stabilize charges.
Covalent catalysis is used to give reaction pathways of lower energy.
Entropy losses are minimized because the necessary catalytic groups are part of the enzyme structure. These features are paid for in two ways. The original synthesis of the enzyme costs energy, although the enzyme is used repeatedly. The enzyme-substrate binding energy is used to immobilize the substrate at the active site and hold it next to the catalytic groups. This binding energy is inherently available for use but it is generally not utilized in uncatalyzed reactions.