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Unformatted text preview: Biochem II Review- Exam 1 I. ENZYMES A B Enzymes cannot alter reactions equilibrium when [A] and [B] are much greater than the concentration of the enzyme, or when [substrates] >>>>[enzyme] In CONTRAST, in vivo: [enzymes][substrates] so enzymes CAN change reaction equilibria under these conditions. 1. Enzymes can hold ATP and keep it from degrading (since ATP spontaneously hydrolyzes to ADP + P, thereby changing its equilibrium 2. An Apoenzyme is the protein part of an enzyme without any co-factors that may be required for the protein to be functional. 3. Co-factors : are small organic or inorganic molecules (most often a non-protein compound) that an apoenzyme requires for its activity (such as NAD+, FAD, metal ions); helps enzyme with enzymatic activities. Addition of a cofactor to an apoenzyme yields a holoenzyme. 4. Substrate: molecule acted upon by the enzyme to form a product. The pocket in the enzyme is referred to as substrate-binding site, or often as the active site. a. Substrate specificity resides in a particular region on the enzyme surface, called substrate-binding site which is a particular arrangement of amino acid side chains that are formulated to bind a specific substrate. b. Some enzymes have a region of the molecule, the allosteric site, that is not at the substrate-binding site, but is a unique site where small molecules bind and effect a change in the substrate-binding or catalytic activity of an enzyme 5. There are 6 major classes of enzymes: oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases....
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