Harrington P C, Wilkins R G
Biochemistry. 1985 Jan 1;24(1):210-4. doi: 10.1021/bi00322a030.
The reactions of hemerythrin from Phascolopsis gouldii with the specific sulfhydryl reagents 5,5'-dithiobis(2-nitrobenzoate), 2,2'-dithiodipyridine, and 4,4'-dithiodipyridine were studied at 25 degrees C. Spectrophotometric measurements showed that 1 mol of disulfide reacted per protein subunit consistent with a single cysteine at residue 50. Reaction leads to dissociation of the octameric structure of the native protein to monomers. The first-order rate constants at 25 degrees C and pH 9.0 for reactions of methemerythrin [(1.5 +/- 0.3) X 10(-3) s-1] and metazidohemerythrin [(4.0 +/- 0.3) X 10(-3) s-1] are independent of both the concentration and the nature of the disulfide. The reactions of methemerythrin are strongly inhibited by ClO4-ion, which however has no effect on the rates of those of metazidohemerythrin. The first-order kinetic behavior is ascribed to a conformational change involving the protein controlling the reaction, and this slow change appears to dominate a number of the reactions of hemerythrin.
在25℃下研究了古氏管体虫血蓝蛋白与特定巯基试剂5,5'-二硫代双（2-硝基苯甲酸）、2,2'-二硫代二吡啶和4,4'-二硫代二吡啶的反应。分光光度测量表明，每摩尔蛋白质亚基与1摩尔二硫化物反应，这与第50位残基处的单个半胱氨酸一致。反应导致天然蛋白质的八聚体结构解离为单体。在25℃和pH 9.0条件下，高铁血蓝蛋白[(1.5±0.3)×10⁻³ s⁻¹]和高铁叠氮血蓝蛋白[(4.0±0.3)×10⁻³ s⁻¹]反应的一级速率常数与二硫化物的浓度和性质均无关。高铁血蓝蛋白反应受到高氯酸根离子的强烈抑制，但高氯酸根离子对高铁叠氮血蓝蛋白的反应速率没有影响。一级动力学行为归因于涉及控制反应的蛋白质的构象变化，这种缓慢变化似乎主导了血蓝蛋白的许多反应。
