Open AccessProperties of Malonyl‐CoA Decarboxylase and its Relation with Malonyl‐CoA Incorporation into Fatty Acids by Rat Liver Mitochondria
Author(s) -
Landriscina Clemente,
Gi Gabriele V.,
Quagliariello Ernesto
Publication year - 1971
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1971.tb01351.x
Subject(s) - malonyl coa , mitochondrion , biochemistry , aromatic l amino acid decarboxylase , chemistry , carboxy lyases , fatty acid , coenzyme a , enzyme , beta oxidation , biology , reductase
1 Malonyl‐CoA decarboxylase in rat liver, heart, kidney and brain is mainly a mitochondrial enzyme associated with the matrix space. 2 The Michaelis constant for this enzyme, in rat liver mitochondria, has been calculated as 42 μM. 3 N ‐Ethylmaleimide, p ‐chloromercuribenzoate and palmityl‐CoA, but not arsenite, inhibit malonyl‐CoA decarboxylase. The inhibition by –SH group blocking reagents is prevented by β‐mercaptoethanol and is competitive with respect to substrate malonyl‐CoA. The inhibition by palmityl‐CoA is an “uncompetitive” type. 4 [1,3‐ 14 C]Malonyl‐CoA is incorporated at almost the same rate as [1‐ 14 C]acetyl‐CoA into fatty acids by rat liver mitochondria. In both cases only chain elongation of endogenous fatty acids is observed. By making use of inhibitors of malonyl‐CoA decarboxylase, clear evidence is obtained that malonyl‐CoA is decarboxylated to acetyl‐CoA before its incorporation into fatty acids by mitochondria. 5 At concentrations more than twice that which completely inhibit malonyl‐CoA decarboxylase, p ‐chloromercuribenzoate and palmityl‐CoA also inhibit fatty acid synthesis in rat liver mitochondria. 6 The possible physiological role of malonyl‐CoA decarboxylase in cellular metabolism is discussed.