title: Structural characterization of cytosolic NADP(+)-dependent isocitrate dehydrogenase from rat ovary.
abstract: Cytosolic NADP(+)-dependent isocitrate dehydrogenase was purified to homogeneity from superovulated rat ovaries. Amino acid sequence information was obtained by analyzing peptides generated by digestion with either cyanogen bromide or trypsin. Eleven peptides were sequenced and a total of 146 amino acids were identified. Nine of these peptides were found to be 60-100% identical with sequences from mitochondrial NADP(+)-dependent isocitrate dehydrogenase. Conservation of amino acids was observed for residues that were previously identified as potentially binding isocitrate-Mg2+. Circular dichroism measurements showed that the structure is composed of approximately 35% alpha-helix and 21% beta-sheet segments. Temperature denaturation studies indicated that the enzyme is more stable in the presence of isocitrate.
authors.affiliation: Laboratory of Experimental Carcinogenesis, National Cancer Institute, Bethesda, Md., USA.
authors.forename: S
authors.initials: S
authors.lastname: Sechi
authors.forename: D
authors.initials: D
authors.lastname: Parmelee
authors.forename: P P
authors.initials: PP
authors.lastname: Roller
authors.forename: G T
authors.initials: GT
authors.lastname: Jennings
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D003600:Cytosol / Q000201:enzymology; D005260:Female; D007521:Isocitrate Dehydrogenase / Q000737:chemistry* / Q000302:isolation & purification; D007523:Isocitrates / Q000494:pharmacology; D008969:Molecular Sequence Data; D010053:Ovary / Q000201:enzymology*; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D051381:Rats; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D013696:Temperature
chemical_list: D007523:Isocitrates; C034219:isocitric acid; D007521:Isocitrate Dehydrogenase; C039355:isocitrate dehydrogenase (NADP+)