On the temperature stability of extracellular hemoglobin of Glossoscolex paulistus, at different oxidation states: SAXS and DLS studies

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• 作者：José ; Wilson P. Carvalho^a ; Patrí ; cia S. Santiago^a ; ^b ; Tatiana Batista^a ; Carlos Ernesto Garrido Salmon^c ; Leandro R.S. Barbosa^d ; Rosangela Itri^d ; Marcel Tabak^a ; ^{marcel@sc.usp.br}
• 关键词：Extracellular hemoglobin ; Glossoscolex paulistus ; Oligomeric dissociation ; Thermal stability ; DLS ; SAXS
• 刊名：Biophysical Chemistry
• 出版年：2012
• 期刊代码：11_03014622
• 类别：ch
• 出版时间：April, 2012
• 卷：163-164
• 期：Complete
• 页码：44-55
• 文件大小：1131 K

摘要

Glossoscolex paulistus hemoglobin (HbGp) was studied by dynamic light scattering (DLS) and small angle X-ray scattering (SAXS). DLS melting curves were measured for met-HbGp at different concentrations. SAXS temperature studies were performed for oxy-, cyanomet- and met-HbGp forms, at several pH values. At pH 5.0 and 6.0, the scattering curves are identical from 20 to 60 掳C, and R_g is 108 脜, independent of the oxidation form. At pH 7.0, protein denaturation and aggregation occurs above 55 掳C and 60 掳C, for oxy and met-HbGp, respectively. Cyanomet-HbGp, at pH 7.0, is stable up to 60 掳C. At alkaline pH (8.0-9.0) and higher temperature, an irreversible dissociation process is observed, with a decrease of R_g, D_max and I(0). Analysis by p(r), obtained from GNOM, and OLIGOMER, was used to fit the SAXS experimental scattering curves by a combination of theoretical curves obtained for HbLt fragments from the crystal structure. Our results show clearly the increasing contribution of smaller molecular weight fragments, as a function of increasing pH and temperature, as well as, the order of thermal stabilities: cyanomet- > oxy- > met-HbGp.