Characterization of gastric mucoproteins isolated by equilibrium density-gradient centrifugation in caesium chloride.
Characterization of gastric mucoproteins isolated by equilibrium density-gradient centrifugation in caesium chloride.
复制标题
氯化铯平衡密度梯度离心分离胃粘蛋白的表征。
作者：
B. Starkey;D. Snary;A. Allen
1.猪胃粘液粘蛋白经CsCl梯度平衡离心纯化。2.该过程去除了非共价结合的蛋白质，其与粘蛋白紧密结合，并且不容易通过凝胶过滤从粘蛋白中去除。3.纯化的粘蛋白可通过凝胶过滤分离成高分子量粘蛋白A（mol. 2.3x10（6））和低分子量粘蛋白B/C（mol. 1.15x10（6））。4.这两种粘蛋白具有相同的化学分析，即岩藻糖11.3%、半乳糖26%、葡糖胺19.5%、半乳糖胺8.3%和蛋白质13.6%。5.粘蛋白A含有3.1%的硫酸酯。6.这些粘蛋白是在没有酶消化的情况下分离的，并且具有比来自胃粘液的蛋白水解消化的血型物质粘蛋白更高的蛋白质含量。详细的氨基酸分析表明，非酶消化材料中的额外蛋白质由丝氨酸和苏氨酸以外的氨基酸组成。7.粘蛋白A和B/C每分子分别含有130和9个半胱氨酸残基，其中约78和6个残基涉及二硫键。8.巯基乙醇裂解这些二硫键将两种粘蛋白分成四个大小相等的分子量亚基。粘蛋白A为5.2x10（5），粘蛋白B/C为2.8x10（4）。9.粘蛋白A的唯一N-末端氨基酸是天冬氨酸，而粘蛋白B/C具有几个不同的N-末端氨基酸残基。
1. The mucoprotein from pig gastric mucus has been purified by equilibrium centrifugation in a CsCl gradient. 2. This procedure removes the non-covalently bound protein, which is closely associated with the mucoprotein and not easily removed from it by gel filtration. 3. The purified mucoprotein is separable by gel filtration into a high-molecular-weight mucoprotein A (mol.wt. 2.3x10(6)) and a low-molecular-weight mucoprotein B/C (mol.wt. 1.15x10(6)). 4. These two mucoproteins have the same chemical analysis namely fucose 11.3%, galactose 26%, glucosamine 19.5%, galactosamine 8.3% and protein 13.6%. 5. Mucoprotein A contains 3.1% ester sulphate. 6. These mucoproteins are isolated without enzymic digestion and have a higher protein content than the blood-group-substance mucoproteins from proteolytic digestion of gastric mucus. Detailed amino acid analysis shows that the extra protein in the non-enzymically digested material is composed of amino acids other than serine and threonine. 7. Mucoproteins A and B/C contain respectively 130 and 9 half-cystine residues per molecule of which about 78 and 6 residues are involved in disulphide linkages. 8. Cleavage of these disulphide linkages by mercaptoethanol splits both mucoproteins into four equally sized subunits of mol.wt. 5.2x10(5) for mucoprotein A and 2.8x10(4) for mucoprotein B/C. 9. The sole N-terminal amino acid of mucoprotein A is aspartic acid, whereas mucoprotein B/C has several different N-terminal amino acid residues.