The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima 890-0065 Japan.
Biochem Cell Biol. 2011 Dec;89(6):533-44. doi: 10.1139/o11-041. Epub 2011 Oct 17.
The interaction of egg-white lysozyme with N-ovalbumin, the native form of egg-white ovalbumin with the denaturation temperature, T(m), of 78 °C, was investigated by the inhibition of lysozyme muramidase activity, differential scanning calorimetry, and circular dichroism assay as indicators. Signals for the interaction were the most prominent when the mixture of lysozyme and N-ovalbumin was co-heated at 72 °C, slightly lower than the T(m) of N-ovalbumin. The interaction was also marked when unheated lysozyme was mixed with N-ovalbumin preheated at 72 °C. Moreover, the mixture rapidly formed fibrous precipitates, which were positive for thioflavin T fluorescent emission, a marker for the amyloid fibril formation. Also electron microscopic observation exhibited features of fibrils. The interaction potency of ovalbumin was ascribed to the tryptic fragment ILELPFASGT MSMLVLLPDE VSGLEQLESIINFEK (residues 229-263), derived from the 2B strands 2 and 3 of ovalbumin. From lysozyme, on the other hand, the chymotryptic peptide RNRCKGTDVQAW (residues 112-123), including cluster 6, and the chymotryptic/tryptic peptide GILQINSRW (residues 54-62), including cluster 3, were responsible for the interaction with N-ovalbumin. Interestingly, this nonamer peptide was found to have the ability to self-aggregate. To the authors knowledge, this may be the first report to document the possible involvement of dual proteins in the formation of amyloid-like fibrils.
蛋清溶菌酶与 N-卵清蛋白（蛋清卵清蛋白的天然形式，变性温度 T(m)为 78°C）的相互作用通过抑制溶菌酶溶菌酶活性、差示扫描量热法和圆二色性分析来研究。当混合物在 72°C 下共加热时，溶菌酶和 N-卵清蛋白的混合物表现出最显著的相互作用信号，略低于 N-卵清蛋白的 T(m)。当未加热的溶菌酶与在 72°C 下预加热的 N-卵清蛋白混合时，也可以明显看出相互作用。此外，混合物迅速形成纤维状沉淀物，对硫黄素 T 荧光发射呈阳性，这是淀粉样纤维形成的标志物。电子显微镜观察也表现出纤维的特征。卵清蛋白的相互作用能力归因于源自卵清蛋白 2B 链 2 和 3 的胰蛋白酶片段 ILELPFASGT MSMLVLLPDE VSGLEQLESIINFEK（残基 229-263）。另一方面，来自溶菌酶的 Chymotrypsin 肽 RNRCKGTDVQAW（残基 112-123），包括簇 6，以及 Chymotrypsin/Trypsin 肽 GILQINSRW（残基 54-62），包括簇 3，负责与 N-卵清蛋白相互作用。有趣的是，这种非九肽被发现具有自聚集的能力。据作者所知，这可能是第一个记录双蛋白可能参与形成类似淀粉样纤维的报告。
