Brennan S O
Molecular Pathology Laboratory, Canterbury Health Laboratories, Christchurch Hospital, New Zealand.
Clin Chem. 1998 Nov;44(11):2264-9.
Both normal albumin (Al A) and genetically modified forms were isolated from six heterozygous subjects. Albumins from each individual were analyzed by electrospray ionization mass spectrometry (ESI MS), and the mass was compared with that predicted from the protein sequence. In all cases, the Al A was heterogeneous, with components of mass (+/- SE) 66463+/-4, 66586+/-3, and 66718+/-5 Da. Each genetic variant showed similar heterogeneity. The mass increase in Al Casebrook (2214 Da) was very close to that predicted (2205 Da) from protein and carbohydrate sequence analysis, whereas the increase in Al Redhill (2378 Da) was close to that expected (2392 Da) for an Arg-albumin with a disialylated N-linked biantennary oligosaccharide and an Ala-->Thr mutation. The circulating proalbumins, Christchurch and Blenheim, had mass increases of 748 and 756 Da, respectively, over Al A; in excellent agreement with theoretical values of 744 and 756. Clear shifts in mass were also detected for the point substitutions 177Cys-->Phe (44 Da), 1Asp-->Val (20 Da), and Arg-albumin (160 Da).
从6名杂合子受试者中分离出正常白蛋白（Al A）和基因改造形式的白蛋白。对每个个体的白蛋白进行电喷雾电离质谱分析（ESI MS），并将质量与根据蛋白质序列预测的质量进行比较。在所有情况下，Al A都是异质的，其质量组分（±标准误差）为66463±4、66586±3和66718±5 Da。每个基因变体都表现出相似的异质性。Al Casebrook的质量增加（2214 Da）与蛋白质和碳水化合物序列分析预测的质量增加（2205 Da）非常接近，而Al Redhill的质量增加（2378 Da）与具有双唾液酸化N-连接双天线寡糖和Ala→Thr突变的精氨酸白蛋白预期的质量增加（2392 Da）接近。循环中的前白蛋白Christchurch和Blenheim比Al A的质量分别增加了748和756 Da；与理论值744和756高度一致。对于177Cys→Phe（44 Da）、1Asp→Val（20 Da）和精氨酸白蛋白（160 Da）的点突变，也检测到了明显的质量位移。
