Cumsky M G, Zusman D R
J Biol Chem. 1981 Dec 10;256(23):12581-8.
Myxococcus xanthus is a Gram-negative bacterium that has a complex life cycle which includes cellular aggregation and sporulation. During the period of cellular aggregation, a lectin-like protein called myxobacterial hemagglutinin (MBHA) is synthesized. A four-step purification procedure for MBHA is described. It consists of chromatography on DEAE-cellulose, CM-cellulose, and hydroxyapatite, followed by gel filtration on Bio-Gel P-30. This procedure gives good yields of MBHA (40-50%) free of contaminating proteins. The purified protein has been partially characterized. It exists as a monomer in solution with an apparent Mr = 28,000 and an isoelectric point of 8.3. The amino acid composition of MBHA has been determined. It shows a very high content of glycine (19%) as well as aromatic amino acids (9%); it has a low percentage of charged amino acids. No detectable carbohydrate was found in a large sample (50 micrograms) of MBHA. The far-ultraviolet CD spectrum of MBHA indicates a secondary structure which contains very little alpha-helix, 50 +/- 10% beta-sheet, and 50 +/- 10% random coil. MBHA comprises 1-2% of soluble protein of M. xanthus at the time of cellular aggregation. The fact that it is a lectin suggests that it may play a role in cell-cell recognition or adhesion.
黄色黏球菌是一种革兰氏阴性菌，具有复杂的生命周期，包括细胞聚集和孢子形成。在细胞聚集期间，会合成一种名为黏细菌血凝素（MBHA）的类凝集素蛋白。本文描述了一种MBHA的四步纯化程序。该程序包括在DEAE-纤维素、CM-纤维素和羟基磷灰石上进行色谱分离，随后在Bio-Gel P-30上进行凝胶过滤。该程序可获得高产率（40 - 50%）且不含污染蛋白的MBHA。已对纯化后的蛋白进行了部分表征。它在溶液中以单体形式存在，表观分子量为28,000，等电点为8.3。已测定了MBHA的氨基酸组成。结果显示其甘氨酸含量非常高（19%）以及芳香族氨基酸含量也较高（9%）；其带电荷氨基酸的比例较低。在50微克的大样本MBHA中未检测到碳水化合物。MBHA的远紫外圆二色光谱表明其二级结构中几乎不含有α-螺旋，β-折叠占50±10%，无规卷曲占50±10%。在细胞聚集时，MBHA占黄色黏球菌可溶性蛋白的1 - 2%。它作为一种凝集素这一事实表明它可能在细胞间识别或黏附中发挥作用。
