کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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5371216 | 1503944 | 2012 | 12 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: On the temperature stability of extracellular hemoglobin of Glossoscolex paulistus, at different oxidation states: SAXS and DLS studies On the temperature stability of extracellular hemoglobin of Glossoscolex paulistus, at different oxidation states: SAXS and DLS studies](/preview/png/5371216.png)
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 °C, and Rg is 108 à , independent of the oxidation form. At pH 7.0, protein denaturation and aggregation occurs above 55 °C and 60 °C, for oxy and met-HbGp, respectively. Cyanomet-HbGp, at pH 7.0, is stable up to 60 °C. At alkaline pH (8.0-9.0) and higher temperature, an irreversible dissociation process is observed, with a decrease of Rg, Dmax 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.
Highlights⺠Glossoscolex paulistus hemoglobin (HbGp) was studied by DLS and SAXS. ⺠The thermal stability order is cyanomet->, oxy->, met-HbGp, at several pH values. ⺠Analyses of SAXS experimental curves were performed by GNOM and OLIGOMER. ⺠Experimental p(r) curves were anayzed by a linear combination of HbLt fragments. ⺠Contributions from smaller fragments were observed at higher pH and temperature.
Journal: Biophysical Chemistry - Volumes 163â164, April 2012, Pages 44-55