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MITOCHONDRIAL—ASSOCIATED CDP—DIACYLGLYCEROL SYNTHASE ACTIVITY IN GERMINATING SOYBEANS
Author(s) -
CARMAN GEORGE M.,
AMEGAH RUBY,
MATAS JONATHAN
Publication year - 1980
Publication title -
journal of food biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 47
eISSN - 1745-4514
pISSN - 0145-8884
DOI - 10.1111/j.1745-4514.1980.tb00785.x
Subject(s) - phosphatidic acid , diacylglycerol kinase , enzyme , biochemistry , chemistry , atp synthase , enzyme assay , phospholipid , protein kinase c , membrane
The mitochondrial‐associated CTP: phosphatidic acid cytidylyltransferase (CDP‐diacylglycerol synthase, EC 2.7.7.41) was studied from germinating soybeans. The enzyme exhibited a broad pH optimum between pH 6.5 and pH 8.0. Activity was dependent on the addition of magnesium ions (20 mM) and the nonionic detergent Triton X‐100 (5 mM). The apparent K m values for CTP and phosphatidic acid were 0.58 mM and 0.12 mM, respectively. A V max of 0.12 U/mg was found for the mitochondrial‐associated enzyme. Phospholipids generally stimulated activity while ADP and CDP strongly inhibited activity. Thiore‐active agents inhibited activity indicating that a sulphydryl group is essential for activity. The enzyme was thermally inactivated at temperatures above 35°C.