Enzymes are a class of proteins that are catalytic, they process an accelerated chemical reaction within the living system. All metabolic systems proceed with a series of enzymes, each sequential enzyme acting on the products from the previous enzyme, like an assembly line. Biosynthetic/biodegredation pathways rely on enzymes for efficient processes.
Atoms in the enzyme move to assist in forming and/or breaking covalent bonds in the substrate molecule by providing the right pH or some unknown condition that permits the reaction to proceed faster than it would otherwise outside the active site of the catalyst.
Factors that alter tertiary structure or noncovalent bonds (ionic, hydrogen & disulfide bonds that hold higher order shapes in enzymes) can alter how the active site attracts the reactants and how the enzyme moves reactant molecules across the energy barrier. These are the rate limiting factors that impact metabolic efficiency of living organisms.
1. Concentration of both reactants and reaction products relative to the concentration of the enzyme
2. Temperature
3. pH