Effect of Ca2+ on the activity of mitochondrial NADP-specific isocitrate dehydrogenase from rabbit adrenals.
Mitochondrial NADP-specific isocitrate dehydrogenase (ICDH) partially purified from rabbit adrenals is sensitive to low concentrations of Ca2+. In the absence of Ca2+ (addition of 1 mM EGTA) the Km of ICDH for DL-isocitrate was 143 microM, and in the presence of about 10 microM Ca2+ (EGTA-Ca2+ buffer) it was decreased to 55 microM. The Km value of ICDH for NADP was similar in the absence (4.4 microM) and in the presence (5.0 microM) of Ca2+. The Km of mitochondrial NADP-ICDH for DL-isocitrate was higher than that of cytoplasmic NADP-ICDH from the same source.
Strumiło
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Laboratory of Endocrine Glands Biochemistry, Academy of Sciences of Belarus, Grodno, Belarus.
D000311:Adrenal Glands / Q000201:enzymology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D003593:Cytoplasm / Q000201:enzymology; D066298:In Vitro Techniques; D007521:Isocitrate Dehydrogenase / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D008928:Mitochondria / Q000201:enzymology*; D011817:Rabbits
D007527:Isoenzymes; D007521:Isocitrate Dehydrogenase; C039355:isocitrate dehydrogenase (NADP+); D002118:Calcium