Studies on Chem icalCom position ofIron-m olybdenum Cofactor fromNitrogenase by Fluorescence Analysis  

作　　者：ZHANG Feng-zhang XU Liang-shu HUANG He-qing LONG Min-nan QIU Xue-hui CHEN Zhong 

机构地区：[1]Department of Biology,Xiamen University,Xiamen 361005,P.R.China

出　　处：《Chemical Research in Chinese Universities》1999年第3期286-293,共8页高等学校化学研究(英文版)

摘　　要：The iron molybdenum cofactor(FeMoco) of nitrogenase MoFe protein from Azotobacter vinelandii OP was extracted by N methylformamide(NMF). The effects of FeMoco(in NMF) on electronic spectrum and fluorescence intensity of fluorescein dimercury acetate(FDMA)(in 1 mol/L NaOH) were investigated by fluorophotometric titrations and compared with those of (NH 4) 2MoS 4 and complexes of (NH 4) 2MoS 4 with Na 2S or Na 2S 2 or (NH 4) 2S x on the relative properties of FDMA. It was found that the electronic spectrum of FDMA displayed hypsochromic shift(17 nm) in the presence of FeMoco just like that in the presence of other inorganic sulfides and that the titration curve for the quench of FDMA with FeMoco is very similar to that for the quench of FDMA with complex of (NH 4) 2MoS 4 with Na 2S 2(mole ratio is 1∶3). The results showed that FeMoco(N) probably contained S—S bonds and its structure was found to be changed compared with Kim Rees structural model. This change should profit the formation of the polymer.The iron molybdenum cofactor(FeMoco) of nitrogenase MoFe protein from Azotobacter vinelandii OP was extracted by N methylformamide(NMF). The effects of FeMoco(in NMF) on electronic spectrum and fluorescence intensity of fluorescein dimercury acetate(FDMA)(in 1 mol/L NaOH) were investigated by fluorophotometric titrations and compared with those of (NH 4) 2MoS 4 and complexes of (NH 4) 2MoS 4 with Na 2S or Na 2S 2 or (NH 4) 2S x on the relative properties of FDMA. It was found that the electronic spectrum of FDMA displayed hypsochromic shift(17 nm) in the presence of FeMoco just like that in the presence of other inorganic sulfides and that the titration curve for the quench of FDMA with FeMoco is very similar to that for the quench of FDMA with complex of (NH 4) 2MoS 4 with Na 2S 2(mole ratio is 1∶3). The results showed that FeMoco(N) probably contained S—S bonds and its structure was found to be changed compared with Kim Rees structural model. This change should profit the formation of the polymer.

关 键 词：NITROGENASE Iron molybdenum cofactor Fluorophotometric titration Structural change 

分 类 号：O657.3[理学—分析化学]