小麦麸皮抗冻蛋白的纯化及理化性质的研究

Purification and physical-chemical characteristic of a novel antifreeze protein from wheat bran(wb AFP)

本文纯化了一种小麦麸皮抗冻蛋白,并对其氨基酸组成、二级结构进行了分析。采用粗分离、饱和硫酸铵沉淀、离子交换色谱（DEAE-cellulose-26）、凝胶过滤色谱（Sephadex G75）四步对其进行纯化,纯化倍数为449.99倍,产率为4.17%,分子量为11.2 ku,热滞活性为0.169℃（5 mg/m L）。氨基酸组成结果表明：其甘氨酸含量较高（52.08 mol%）,亲水性好。将其与几种常见抗冻糖蛋白进行相关性分析,推断其是一种与冷诱导相关的蛋白。采用傅里叶红外光谱检测,获得其二级结构为：α-螺旋：25.96%~26.52%,β-折叠：21.69%~23.78%,β-转角：35.31%~37.61%,无规卷曲：13.69%~15.08%。

A novel antifreeze protein from wheat bran（wbAFP） was purified and the amino acid composition and the secondary structure were studied. This AFP was purified by four steps-crude extracted,ammonium sulfate precipitation, anion-exchange chromatography on a DEAE-cellulose-26 column, and size-exclusion chromatography on a Sephadex G75 column. As a result, wbAFP was purified 449.99 fold,yielding a productivity of 4,17%. The molecular weight was 11.2 ku and the thermal hysteresis activity（THA） was 0.169 ℃ at a concentration of 5 mg/mL. The result of amino acid composition of wbAFP showed that it was glycine-rich （52.08 mol%） and had a relatively high hydrophilicity. Compared with several common antifreeze glycoproteins （AFGPs） it was inferred that wbAFP was related with cold-inducible protein. The secondary structure was determined by FT-IR spectra. The results were summarized as α-helix of 25.96%-26.52%,13-sheet of 21.69% N23.78%,β-turn of 35.31%-37.61% and random coil of 13.69%-15.08%.