Garrick L M, McDonald M J, Shapiro R, Bleichman M, McManus M, Bunn H F
Eur J Biochem. 1980 May;106(2):353-9. doi: 10.1111/j.1432-1033.1980.tb04581.x.
Human hemolysate contains several minor hemoglobin components, including Hb AIa1, Hb AIa2, Hb AIb and Hb AIc which are post-translational modifications of the major component, Hb A0. Hb AIc is known to contain glucose attached to the N terminus of the beta chains by a ketoamine linkage. We separated the alpha and beta globin chains from purified Hb AIa1, Hb AIa2 and Hb AIb by ion-exchange chromatography. The beta chains were reducible by sodium borohydride and gave a positive thiobarbituric acid test. These results indicated that they are modified by ketoamine-linked carbohydrate. In addition, phosphate analysis revealed 1.5 phosphate residue associated with each beta AIa1 chain and 1 phosphate residue with each beta AIa2 chain. Hb AIa1, Hb AIa2 and Hb AIb were all found to be contaminated by non-globin proteins. Protein-sequencing approaches demonstrated that the N termini of beta AIa1, beta AIa2 and beta AIb were blocked. In support of this conclusion, analysis of tryptic digests of beta AIa2 and B AIb revealed modified N-terminal peptides. We conclude that, like Hb AIc, components Hb AIa1, Hb AIa2 and Hb AIb also contain a sugar moiety linked to the N terminus of the beta chain.
人溶血产物含有几种次要的血红蛋白成分，包括Hb AIa1、Hb AIa2、Hb AIb和Hb AIc，它们是主要成分Hb A0的翻译后修饰产物。已知Hb AIc含有通过酮胺键连接到β链N末端的葡萄糖。我们通过离子交换色谱法从纯化的Hb AIa1、Hb AIa2和Hb AIb中分离出α和β珠蛋白链。β链可被硼氢化钠还原，并给出阳性硫代巴比妥酸试验结果。这些结果表明它们被酮胺连接的碳水化合物修饰。此外，磷酸盐分析显示每个β AIa1链有1.5个磷酸盐残基，每个β AIa2链有1个磷酸盐残基。发现Hb AIa1、Hb AIa2和Hb AIb均被非珠蛋白污染。蛋白质测序方法表明β AIa1、β AIa2和β AIb的N末端被封闭。为支持这一结论，对β AIa2和β AIb的胰蛋白酶消化产物分析显示有修饰的N末端肽段。我们得出结论，与Hb AIc一样，Hb AIa1、Hb AIa2和Hb AIb成分也含有连接到β链N末端的糖部分。
