岩藻多糖酶的FTIR光谱研究

通过海洋真菌LD8固态发酵获得岩藻多糖的粗蛋白，并进一步采用柠檬酸缓冲液浸提、丙酮沉淀和葡聚糖凝胶G-100层析，分离纯化至单一组分；利用傅里叶变换红外光谱(fourier transform infrared spectroscopy,FTIR)及曲线拟合等技术研究了岩藻多糖酶的二级结构组成，增强因子为2.2，半峰宽为20.2 cm-1；为提高分析测定的准确性，对酰胺Ⅰ带与酰胺Ⅲ带分别进行拟合归属。结果表明：根据酰胺Ⅰ带所获得的二级结构，α-螺旋占11.5%，β-折叠为58.6%,无规卷曲14.5%,β-转角15.9%；酰胺Ⅲ带所得二级结构，α-螺旋含12%，β-折叠含57.3%,无规卷曲含14.5%,β-转角含16.3%。因此可见，酰胺Ⅰ带与酰胺Ⅲ带所对二级结构的分析是十分吻合的。在室温下，岩藻多糖酶的二级结构以β-折叠的含量占优势，约占58%，β-转角和无规卷曲次之，各占15%左右，α-螺旋含量较低，仅占12%。

Investigation of Fucoidanase by FTIR Spectra

Fucoidanase was isolated and purified from marine fungus LD8 by solid state fermentation, extraction with citric acid buffer, acetone precipitatation and column chromatography on Sephadex G-100. A single band on PAGE shows that pretty pure fucoidanase has been obtained. FT-IR spectra and its derivation, self-deconvolution and curve-fitting methods were used to analyze the secondary structure of the fucoidanase. Composite bands of the amide I and amide III were studied by using Fourier self-deconvolution (FSD) with an enhancement factor of K = 2.2 and a half width of 20.2 cm(-1). The relative average fractions of alpha-helix, beta-sheet, random coil, beta-turn are 11.5%, 58.6%, 14.5% and 15.9%, respectively, according to amide I region, while the content of alpha-helix is 12%, beta-sheet 57.3%, random coil 14.5%, and beta-turn 16.3% on amide III region. In other words, both the conclusions were exactly consistent. All the above results show that beta-sheet was the dominant component, which is about 58%, and that beta-turn is about 15%, random coil 15%, and alpha-helix 12% at room temperature.