Purification and structural characterization of porcine L-threonine dehydrogenase.
L-Threonine dehydrogenase was purified 10,000-fold to a specific activity approximately 300 mumol.min-1.mg-1 protein from porcine liver mitochondria. Purification to apparent homogeneity was achieved by sequential chromatography on DEAE Sepharose FF, Affi-Gel Blue, Sephacryl S-200, Matrex Gel Red A, and Matrex Gel Green A. The subunit molecular mass was estimated as 37 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, while an apparent native molecular mass of 73 kDa was shown by gel filtration chromatography, suggesting a dimeric structure. The purified enzyme was subjected to proteolytic degradation and the resulting peptides were isolated exclusively by reverse-phase high-performance liquid chromatography. Approximately 70% of the total sequence was obtained and the N-terminal amino acid sequence of the intact polypeptide chain was thus tentatively extended to residue 40.
Kao
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Department of Chemistry, University of Iowa, Iowa City 52242.
Davis
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D000429:Alcohol Oxidoreductases / Q000737:chemistry* / Q000302:isolation & purification; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002850:Chromatography, Gel; D008930:Mitochondria, Liver / Q000201:enzymology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D010449:Peptide Mapping; D017421:Sequence Analysis; D013237:Stereoisomerism; D013379:Substrate Specificity; D013552:Swine; D013912:Threonine / Q000378:metabolism*
D000596:Amino Acids; D010446:Peptide Fragments; D013912:Threonine; D000429:Alcohol Oxidoreductases; C023159:L-threonine 3-dehydrogenase