Takahashi S, Yip W C, Tamura G
Department of Bioresources Chemistry, Faculty of Horticulture, Chiba University, Japan.
Biosci Biotechnol Biochem. 1997 Sep;61(9):1486-90. doi: 10.1271/bbb.61.1486.
Ferredoxin-sulfite reductase (Fd-SiR) [hydrogen-sulfide: ferredoxin oxidoreductase, EC 1.8.7.1] from turnip leaves (SiR-L) has been purified to homogeneity and its enzymatic properties compared with that from turnip roots (SiR-R). Each enzyme had a molecular mass of 64.5 +/- 0.5 kDa by SDS-PAGE and an isoelectric point of 5.15 +/- 0.05. Although each had a pH optimum around 7.8 with the same effects of inhibitors, SiR-L had higher heat stability at 60 degrees C than SiR-R. Moreover, SiR-R had a lower K(m) and a higher specificity constant (kcat/K(m)) for turnip leaf ferredoxin than SiR-L. The N-terminal amino acid sequence of SiR-L was different from that of SiR-R. The results of amino acid analysis and peptide mapping suggested that SiR-L and SiR-R have different primary structures.
