Muratsubaki H, Enomoto K
Department of Clinical Biochemistry, Kyorin University School of Health Sciences, Tokyo, Japan.
Arch Biochem Biophys. 1998 Apr 15;352(2):175-81. doi: 10.1006/abbi.1998.0583.
Soluble fumarate reductase from yeast irreversibly catalyzes the reduction of fumarate to succinate and has noncovalently bound flavin adenine dinucleotide. In yeast, there are two isoenzymes of fumarate reductase, which can be distinguished on the basis of their absorption or nonabsorption to DE-52 columns. Previously, we have purified FRDS1 and isolated its gene (FRDS) from Saccharomyces cerevisiae. In the present study, FRDS2 was purified to homogeneity by four chromatography steps. The N-terminal and C-terminal amino acid sequences of FRDS2 were identical to the deduced amino acid sequence of the OSM1 gene (EMBL Database Accession No. L-26347), whose isolation and biochemical properties have not been studied up until now. From these results, we conclude that FRDS2 is encoded by the OSM1 gene. The deduced amino acid sequence of the OSM1 gene revealed that FRDS2 is synthesized as a precursor protein containing a presequence composed of 32 amino acid residues. The mature enzyme consists of a protein of 469 amino acid residues with a molecular weight of 51,370. The N-terminal extension had the characteristics of a typical signal sequence required for targeting and sorting to a noncytosolic destination. In fact, FRDS2 was found to be located in promitochondria.
来自酵母的可溶性延胡索酸还原酶不可逆地催化延胡索酸还原为琥珀酸，并具有非共价结合的黄素腺嘌呤二核苷酸。在酵母中，有两种延胡索酸还原酶同工酶，可根据它们对DE-52柱的吸附或不吸附来区分。此前，我们已从酿酒酵母中纯化了FRDS1并分离出其基因（FRDS）。在本研究中，通过四个色谱步骤将FRDS2纯化至同质。FRDS2的N端和C端氨基酸序列与OSM1基因（EMBL数据库登录号L-26347）推导的氨基酸序列相同，到目前为止尚未对其进行分离和生化特性研究。根据这些结果，我们得出结论，FRDS2由OSM1基因编码。OSM1基因推导的氨基酸序列表明，FRDS2作为前体蛋白合成，含有由32个氨基酸残基组成的前导序列。成熟酶由一个469个氨基酸残基的蛋白质组成，分子量为51370。N端延伸具有靶向和分选到非胞质目的地所需的典型信号序列的特征。事实上，发现FRDS2位于前线粒体中。
