Studies on the a

[摘要] Purpose: a-Crystallin belongs to a class of small heat shockproteins and is shown to prevent aggregation of several proteins. Wehave shown that the temperature-induced structural perturbation leads toseveral fold enhanced activity. The purpose of this study was toinvestigate the availability and specificity of the hydrophobic sitesthat might become available at elevated temperatures. Specifically, weaddress the following question: Is there an increased exposure of fixednumber of hydrophobic sites as a function of temperature or does a newset of sites become available at elevated temperatures?Methods: a-Crystallin target protein complexes were made at twodifferent temperatures and this complex was investigated for itschaperone-like activity towards the same target protein and also othertarget proteins. DTT-induced aggregation of insulin, a-lactalbumin,thermal aggregation of bL- and g-crystallin, andphoto-aggregation of g-crystallin were used as model systems.Increased light scattering was used to monitor the progress ofaggregation.Results: a-Crystallin target protein complex prepared at 37°C temperature was effective against thermal aggregation of bL-crystallin as well as non-thermal aggregation at elevatedtemperatures. However, the complex prepared at high temperature wasineffective at lower temperatures as well as with other target proteinsat both temperatures.Conclusions: More target protein binding sites become available atelevated temperatures. The sites available at low temperature are asubset of the total sites available at elevated temperatures.

[学科分类] 生物化学/生物物理