STRUCTURAL CHARACTERIZATION OF A GLYCOPROTEIN VARIANT OF HUMAN SERUM-ALBUMIN - ALBUMIN CASEBROOK (494 ASP-]ASN)
STRUCTURAL CHARACTERIZATION OF A GLYCOPROTEIN VARIANT OF HUMAN SERUM-ALBUMIN - ALBUMIN CASEBROOK (494 ASP-]ASN)
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DOI：
10.1016/0925-4439(91)90023-3
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发表时间：
1991-07-26
期刊：
影响因子：
--
通讯作者：
BRENNAN, SO
中科院分区：
文献类型：
--
作者：
PEACH, RJ;BRENNAN, SO
白蛋白Casebrook是一种相对分子质量比正常白蛋白高2.5 kDa的人白蛋白的电泳速遗传变体。在杂合子携带者中，它约占血清总白蛋白的35%。在与唾液酸酶孵育过程中观察到的负电荷减少，表明存在糖类部分，经Endo-F处理后，分子量归一化，表明这是一种N-连接的寡糖。部分酸解和有限的胰酶消化确定低聚糖位于C-末端结构域，在残基367和585之间。经胰酶、胰凝乳酶和金黄色葡萄球菌V8酶消化后，用刀豆蛋白A-琼脂糖凝胶对糖肽进行纯化。结合组分和非结合组分的多肽图谱、氨基酸组成和序列分析，建立了494个Asp--&Gt；Asn的点突变。这引入了以ASN-494为中心的ASN-Glu-Thr N-连接低聚糖连接序列，并解释了分子质量的增加。这种新的糖化白蛋白在两个不相关的盎格鲁-撒克逊血统的个体中被检测到，没有明显的病理与这种新糖化白蛋白的存在有关。
Albumin Casebrook is an electrophoretically slow genetic variant of human albumin with a relative molecular mass 2.5 kDa higher than normal albumin. It constitutes about 35% of total serum albumin in heterozygous carriers. The decrease in negative charge observed on incubation with sialidase suggested the presence of a carbohydrate moiety and the normalization of molecular weight following treatment with Endo-F indicated that this was an N-linked oligosaccharide. Partial acid hydrolysis and limited tryptic digestion established that the oligosaccharide was located in the C-terminal domain, between residues 367 and 585. Tryptic, chymotryptic and S. aureus V8 proteinase digestions were carried out and the resulting glycopeptides were purified on concanavalin A-Sepharose. Peptide mapping of bound and unbound fractions followed by amino acid composition and sequence analysis, established a point mutation of 494 Asp --> Asn. This introduces an Asn-Glu-Thr N-linked oligosaccharide attachment sequence centred on Asn-494 and explains the increase in molecular mass. There was no apparent pathology associated with the presence of this new glycosylated albumin, which was detected in two unrelated individuals of Anglo-Saxon descent.