METABOLISM OF MALONATE 



233 



incubations (see accompanying tabulation) (Menon et al., 1960). The results 

 show not only differences between the tissues, but also that the activating 

 system for malonate is different from that for succinate and glutarate. 



The metabolic pathways for malonate in mammalian tissues appear to 

 be very similar to those in bacteria. The oxidation of malonate requires 

 ATP, coenzyme A, and Mg++ in extracts or homogenates of rat kidney 

 (Nakada et al., 1957), human placenta (Hosoya and Kawada, 1958), and, 

 incidentally, locust fat body (Tietz, 1961). However, the kinases, decarbox- 



FiG. 1-22. Effects of malonate concentration on the oxidation 



of malonate and acetate by rat kidney slices at pH 7.4 and 



37° during 2-hr incubation. (From Nakada et al., 1957.) 



ylases, and CoA-transferases for these reactions have not been studied. 

 An important transfer of coenzyme A between acetoacetyl-CoA and mal- 

 onate has been shown to occur in pig heart extracts (Beinert and Stansly, 

 1953). Acetoacetyl-CoA is formed by the condensation of two acetyl-CoA 



