Enzyme amount physiological patterns

Just as physiological patterns of control over metabolite flow can be recognized, so can physiological patterns of control over the amount of enzyme. Table III lists a convenient classification. Clearly, the amount of enzyme at any time is a summation of the amount formed and the amount destroyed. Two specific patterns controlling formation might be recognized repression by endproducts and induction by substrate or a precursor. It should be stressed that the terms "repression" and "induction" are operational and should carry no connotations regarding the mechanisms. 

Irwin and Hein (13) reported a family in which DN and FN values indicated that the father was of the usual phenotype, the mother the atypical phenotype, and the two sons the intermediate phenotype. However, one of the sons had about 25% more cholinesterase activity with benzoylcholine as substrate than did his father. Furthermore, the son s cholinesterase activity was greater than that of his father when tested with several other substrates. The pattern of values for this son indicated that his cholinesterase was qualitatively different from that of anyone else in his family. An unidentified gene that affects the amount of enzyme activity, as well as the qualitative properties of cholinesterase, might exist in this family. However, the findings may have been complicated by a physiologically high level of cholinesterase activity which is found in some children, and which decreases to normal adult values at puberty. 

---