摘要
获得了棕色固氮菌固氮酶钼铁蛋白的针状结晶,大小为2-2.5×25-65微米,成晶所要求的条件不是很严格的。SDS 电泳和氨基酸分析结果表明,钼铁蛋白分子量为250,000。只观察到一种类型亚单位。其中酸性氨基酸占优势。分子氧使针状晶体演变为发状晶丝,晶丝又密集成束。晶束可保存较长时间。氧使钼铁蛋白在电泳时形成高聚合态。
A series of experiments were carried out to study the crystallizing conditions ofMo-Fe protein of Azotobacter vinclandii nitrogenase. Needle-like crystals of Mo-Fe protein were obtained, with crystal size fluctuated inthe range of 2-2.5×25-65μ. The conditions required for crystallization were notvery strict. The molecular weight of Mo-Fe protein was estimated by SDS gel electrophoresisand by amino acid analysis to be approximately 250000. Only one type of subunit wasobserved; in the Mo-Fe protein acidic amino acid was predominant. It was found that oxygen caused the needle-like crystals to transform into hair-like crystals which may aggregate somewhere further into bundles. The latter underanaerobic condition could last for longer time. It was also demonstrated that duringthe gel electrophoresis the formation of a higher molecular weight polymer was depend-ent on the presence of oxygen.
