NMR characterization of physicochemical properties of rat D-dopachrome tautomerase.
D-dopachrome tautomerase (DOPD) catalyzes the conversion of D-dopachrome to 5,6-dihydroxyindole. DOPD was found to have amino acid sequence homology with macrophage migration inhibitor factor (MIF), suggesting that DOPD functions as a proinflammatory cytokine. We here demonstrate the physicochemical properties of DOPD by nuclear magnetic resonance (NMR). The native molecular weight of rat DOPD was about 37 kDa as calculated from Sephadex G-100 column chromatography. Since the deduced molecular weight of its cDNA (117 amino acid residues) is 12.5 kDa, it is assumed that DOPD exists as a homotrimer in native form. Since several methyl proton resonances were observed in the high magnetic field region of the one-dimensional 1H-NMR spectrum, DOPD appeared to have a hydrophobic core in which methyl groups and aromatic groups are located close to each other. From a simple integration of one-dimensional 1H-NMR spectra, the contents of the alpha-helix, beta-strand, and random coil were calculated to be 16%, 68%, and 16%, respectively. Since the denaturation temperature of DOPD is exceedingly high at the range between 90-100 degrees C, it is considered that the high beta-strand content may contribute to its heat stability.
Yoshida
H
H
Department of Polymer Science, Faculty of Science, Hokkaido University, Sapporo, Japan.
Nishihira
J
J
Suzuki
M
M
Hikichi
K
K
D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D004926:Escherichia coli; D019746:Intramolecular Oxidoreductases / Q000737:chemistry* / Q000235:genetics; D008263:Macrophage Migration-Inhibitory Factors / Q000737:chemistry* / Q000235:genetics; D009682:Magnetic Resonance Spectroscopy; D011487:Protein Conformation; D051381:Rats; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
D018076:DNA, Complementary; D008263:Macrophage Migration-Inhibitory Factors; D019746:Intramolecular Oxidoreductases; C042501:dopachrome isomerase