18. Succinyl-Coa Synthetase
1974; Elsevier BV; Linguagem: Inglês
10.1016/s1874-6047(08)60150-x
ISSN1874-6047
Autores Tópico(s)Metabolism and Genetic Disorders
ResumoThis chapter discusses the molecular and catalytic properties of succinyl-CoA synthetase. Succinyl-CoA synthetase catalyzes the reversible reaction, which may be considered to be the interconversion of two kinds of high energy bonds: thiolester and phosphate anhydride. In the forward direction, the reaction represents the “substrate-level” phosphorylation step of the tricarboxylic acid cycle, which in higher organisms is undoubtedly its chief and vital role in metabolism. In the reverse direction, on the other hand, the reaction may be viewed as the nucleoside triphosphate dependent synthesis of succinyl-Cob, an important anabolic precursor of such products as heme and cystathionine; thus, the enzyme may be regarded as serving a predominantly biosynthetic role in organisms, such as the enteric bacteria. In the facultative organism Escherichia coli, for example, production of succinyl-CoA synthetase is repressed 8-10-fold when aerobic growth is based on glucose rather than substrates such as succinate. This reflects the high glycolytic capacity of E. coli and strengthens the concept of the anabolic functions of succinyl-CoA synthetase and other tricarboxylic acid cycle enzymes in such organisms.
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