Are the following examples of general acid/base catalysis, covalent catalysis, catalysis by approximation (proximity effect), or metal-ion catalysis? Complete parts a, b, c, and d.
a)
(b) NMP kinases bring two nucleotides, for example AMP and ATP, together to facilitate the transfer of a phosphoryl group from one nucleotide to the other (creating two ADP). The enzyme positions the adenosine triphosphate (ATP) such that the gamma phosphate group is placed adjacently to the phosphate group of the NMP kinase. This facilitates the transfer of the phosphate between the two molecules.
(c) In aspartate ammonia lyase, a deprotonated serine sidechain performs a nucleophilic attack on a carbonyl carbon of the substrate.
(d) An active site histidine abstracts a proton from a substrate, making it more reactive, then donates the proton back to the product.
