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General Enzymology

  1. The Active Site
    (an array of amino acids that give rise to a field of charges that are stereospecific to a given substrate)

    1. Transaminase - an example of one type of stereospecific enzyme

      • apoenzyme + coenzyme + cofactors = holoenzyme

    2. Catalase - an example of a very complex active site (a metaloporphyrin)

    3. Lactic dehydrogenase (LDH) - an example of an enzyme in which the active site is produced by the coming together of four polypeptides to make a quaternary structure, and add to that a couple of coenzymes. What is more, our genes produce two types of LDH polypeptides - one for the heart muscle and the other for other muscles in the body.

  2. Environmental Effects on the Active Site

    1. Temperature

      1. Reaction rate (Michaelis)

      2. Denaturation

    2. pH (most of the active site amino acid side-chains have weak acid and weak base constituents) (Henderson and Hasselback →)

    3. Ionic promoters - these are the cofactors mentioned above in I,A.

    4. Inhibitors ("anti-catalysts") (Michaelis)

      1. Irreversible

      2. Reversible

    5. Allosterism (Jacob and Monod)