Bioengineering Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
Biochem Biophys Res Commun. 2011 Jan 7;404(1):494-7. doi: 10.1016/j.bbrc.2010.12.009. Epub 2010 Dec 6.
Casein micelles are a major component of milk proteins. It is well known that casein micelles show chaperone-like activity such as inhibition of protein aggregation and stabilization of proteins. In this study, it was revealed that casein micelles also possess a high refolding activity for denatured proteins. A buffer containing caseins exhibited higher refolding activity for denatured bovine carbonic anhydrase than buffers including other proteins. In particular, a buffer containing α-casein showed about a twofold higher refolding activity compared with absence of α-casein. Casein properties of surface hydrophobicity, a flexible structure and assembly formation are thought to contribute to this high refolding activity. Our results indicate that casein micelles stabilize milk proteins by both chaperone-like activity and refolding properties.
酪蛋白胶束是牛奶蛋白的主要成分。众所周知，酪蛋白胶束具有类似分子伴侣的活性，如抑制蛋白质聚集和稳定蛋白质。在这项研究中，发现酪蛋白胶束还具有使变性蛋白质重折叠的高活性。含有酪蛋白的缓冲液对变性牛碳酸酐酶的重折叠活性高于包含其他蛋白质的缓冲液。特别是，含有α-酪蛋白的缓冲液的重折叠活性比没有α-酪蛋白时高约两倍。表面疏水性、结构柔韧性和组装形成等酪蛋白特性被认为是这种高重折叠活性的原因。我们的结果表明，酪蛋白胶束通过分子伴侣样活性和重折叠特性来稳定牛奶蛋白。
