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Physiological roles of animal succinate thiokinases Specific association of the guanine nucleotide‐linked enzyme with haem biosynthesis
Author(s) -
Jenkins T.M.,
Weitzman P.D.J.
Publication year - 1988
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(88)80629-x
Subject(s) - biosynthesis , biochemistry , gtp' , nucleotide , enzyme , metabolic pathway , citric acid cycle , chemistry , coenzyme a , biology , gene , reductase
The discovery of two distinct succinate thiokinases in mammalian tissues, one (G‐STK) specific for GDP/GTP and the other (A‐STK) for ADP/ATP, poses the question of their differential metabolic roles. Evidence has suggested that the A‐STK functions in the citric acid cycle in the direction of succinyl‐CoA breakdown (and ATP formation) whereas one role of the G‐STK appears to be the re‐cycling of succinate to succinyl‐CoA (at the expense of GTP) for the purpose of ketone body activation. A third metabolic participation of succinyl‐CoA is in haem biosynthesis. This communication shows that in chemically induced hepatic porphyria, when the demand for succinyl‐CoA is increased, it is the level of G‐STK only which is elevated, that of A‐STK being unaffected. The results implicate G‐STK in the provision of succinyl‐CoA for haem biosynthesis, a conclusion which is further supported by the observation of a high G‐STK/A‐STK ratio in bone marrow.