紫云英根瘤菌109菌株的氢氧化电子传递链  

Electron Transport Components Involved in Hydrogen Oxidation in Free-living Rhizobium astragalus

作　　者：孙金华 陈秉俭[1] 杨玉锁[1] 宋鸿遇[1] 

机构地区：[1]中国科学院上海植物生理研究所,上海200032

出　　处：《植物生理学报（0257-4829)》1990年第2期158-166,共9页Acta Phytophysiologica Sinica

基　　金：中国科学院自然科学基金;中国科学院青年奖励研究基金

摘　　要：H_2还原减去O_2氧化的差示光谱显示424,522,552,560,603nm峰,鱼腾酮(反竞争性抑制),DBMIB,HQNO,抗霉素A,氰化钠和叠氮化钠(非竞争性抑制)明显抑制吸氢活性,表明细胞色素c,b和a分别参与氢氧化的电子传递。以Dixon作图来确定抑制剂在电子传递链中结合位点数目,鱼腾酮和DBMIB为单位点结合,HQNO和氰化物为双位点结合,HQNO所引起的部份抑制,可使对氰化钠敏感的结合位点消逝。鱼腾酮与HQNO同时存在时,其叠加或累积抑制效果表明,两种类型的细胞色素b参与氢氧化的电子传递,由H_2到O_2的电子传递于细胞色素b处分叉,对氰化物抑制敏感性也有所不同。Resting cells from free-living Rhizobium astragalus were used to study electron transport components involved in H_2 oxidation. H_2-reduced minus O_2-oxidized absorption difference spectra revealed peaks at 552,560 and 603 nm (Fig. 1, Table 1). The electron transport inhibitors rotenone, dibromothymoquinon. (DBMIB), 2-n-hyeptyl-4-hydroxy-quinoline-N-oxide (HQNO), antimycin A, cyanide and azide inhibited H_2 uptake significantly (Table 2, 3), indicating the involvement of cytochromes c, b and a-a_3 respectively in the electron transport. The inhibition by rotenone was anticompetitive (Fig. 4) and that by DBMIB, HQNO, cyanide and azide was noncompetitive (Fig. 2,3,5). Dixon plots (1/v versus inhibitor concentration) were used to determine the number of inhibitor binding sites which wasind icated by the number of different slopes of line of H_2 oxidation. Rotenone and DBMIB has one site each and HQNO and cyanide has two sites each. The disappearence of binding sites which were sensitive to cyanide (Fig. 6) was due to the partial inhibition by HQNO. In the presence of rotenone and HQNO additive inhibition was observed (Table 4), indicating that two kinds of cytochrome b were involved in the H_2 oxidation. A branched electron transport pathway from H_2 to O_2 is proposed, with thebranching point localized at cytochromeb (Fig. 3), and each branch of the pathway has different sensitivity to cyanide inhibition (Fig. 7).

关 键 词：紫云英根瘤菌 氢氧化 电子传递链 

分 类 号：Q945.13[生物学—植物学]