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GLYOXYLATE CYCLE ENZYME ACTIVITIES IN THE CYANOBACTERIUM ANACYSTIS NIDULANS 1
Author(s) -
Eley James H.
Publication year - 1988
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.1529-8817.1988.tb04266.x
Subject(s) - isocitrate lyase , malate synthase , glyoxylate cycle , biology , biochemistry , enzyme , lyase , metabolite , idh1 , mutation , gene
The enzymes of the glyoxylate cycle, isocitrate lyase (EC.4.1.3.1) and malate synthase (EC.4.1.3.2), were measured in cell‐free extracts from the cyanobacterium Anacystis nidulans Drouet during photoautotrophic growth in medium aerated with ordinary air (0.03% CO 2 ). Isocitrate lyase had an average specific activity of 112 nmoles·min −1 ·mg protein −1 whereas malate synthase had an average specific activity of 12.5 nmoles·min −1 ·mg protein −1 . Unpurified isocitrate lyase showed classical Michaelis kinetics with a K m of 8 mM. Isocitrate lyase activity was strongly inhibited by numerous cellular metabolites at 10 mM concentration. The previously reported low specific activity for isocitrate lyase may be due to metabolite inhibition caused by growth in high CO 2 concentrations. The activities reported for isocitrate lyase and malate synthase suggest the operation of the glyoxylate cycle in Anacystis nidulans under CO 2 ‐limiting growth conditions.