Structural Properties of Silkworm Small Heat-Shock Proteins: sHSP19.9 and sHSP20.8
Author(s) -
Md. Tofazzal Hossain,
Satoshi Teshiba,
Yuichi Shigeoka,
Tetsuro Fujisawa,
Yōji Inoko,
Daisuke Sakano,
Kohji Yamamoto,
Yutaka Banno,
Yoichi Aso
Publication year - 2010
Publication title -
bioscience biotechnology and biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.509
H-Index - 116
eISSN - 1347-6947
pISSN - 0916-8451
DOI - 10.1271/bbb.100131
Subject(s) - dithiothreitol , ionic strength , catalase , chemistry , biophysics , precipitation , heat shock protein , incubation , protein aggregation , crystallography , biochemistry , enzyme , biology , organic chemistry , physics , aqueous solution , meteorology , gene
sHSP20.8 and sHSP19.9 are silkworm small-heat shock proteins (sHSPs) comprising a number of polypeptides of molecular sizes of several tens of kilodaltons as subunits. The structural properties of sHSPs were investigated. sHSP19.9 was found to be aggregated by itself during incubation at 60 degrees C. Aggregation was suppressed in the presence of dithiothreitol and at high ionic strength. In contrast, sHSP20.8 was not aggregated. Aggregation of sHSP19.9 was partially suppressed by sHSP20.8 and in the presence of catalase as a target protein. Based on changes in small-angle X-ray scattering, it is possible that the molecular size of sHSP19.9 is larger than that of sHSP20.8, and that their molecular sizes increase with increasing temperature in a reversible, biphasic manner. sHSPs did not protect catalase from thermal inactivation, but protected it from precipitation by forming a soluble complex. sHSP20.8 and sHSP19.9 with dithiothreitol were stable against lyophilization, autoclaving at 120 degrees C, and boiling.
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