海蜇伞部不溶性胶原纤维及酶促溶性胶原蛋白的热稳定性对比研究

Thermal Stability of Insoluble Collagen Fibrils and Pepsin-Solubilized Collagen from Rhopilema esculentum Umbrellas

海蜇(Rhopilema esculentum)是我国传统渔业生产的重要大型经济水母,其伞部胶原蛋白含量丰富,但胶原蛋白对热敏感,对其热稳定性进行研究对海蜇资源的开发利用至关重要。本论文从海蜇伞部提取得到不溶性胶原纤维(ICF)及酶促溶性胶原蛋白(PSC),并对其热稳定性进行对比分析。结果表明,海蜇伞部ICF与PSC的氨基酸组成及分子质量类似于I型胶原蛋白,其高级结构差异亦造成热稳定性的不同。傅里叶变换红外光谱(FT-IR)研究发现,在加热至36℃时,PSC的酰胺I带红外吸收骤然降低,结构发生明显变化,而ICF温度升高至50℃时,酰胺I带红外吸收才开始略有变化,ICF热稳定性优于PSC。二维红外分析研究发现,PSC中310-螺旋结构与ICF中β-折叠结构(低频率)对温度变化最为敏感,除自动峰外,PSC与ICF均存在若干交叉峰,说明热处理过程中各个结构之间存在着分子内和分子间的相互作用。本研究为海蜇胶原蛋白的开发利用提供了一定的理论基础。

Rhopilema esculentum, a large jellyfish, is one of the most economically important traditional fishery products in China. The umbrellas of jellyfish are rich in collagen. Since collagen is temperature-sensitive, it is important to study its thermal stability for the development and utilization of jellyfish resources. In this study, insoluble collagen fibrils（ICFs） and pepsin-solubilized collagen（PSC） were extracted from umbrellas of Rhopilema esculentum, and their thermostability was compared. The results indicated that the amino acid compositions and molecular weights of the ICF and PSC were similar to those of type I collagen, and the differences in the higher-order structure of ICF and PSC led to their different thermal stabilities. Fourier transform infrared spectroscopy（FT-IR） analysis showed that the intensity of the amide I band in the infrared absorption of PSC decreased rapidly, and apparent structural changes occurred when the sample was heated to 36 ℃. When the temperature was raised to 50 ℃, the intensity of the amide I band of ICF changed only slightly, suggesting that thermal stability of ICF is superior to that of PSC. Two-dimensional infrared analysis revealed that 310-helical structures in PSC and β-sheets（low frequency） in ICF were sensitive to temperature changes. In addition to the automatic peak, there were a number of overlapping peaks, revealing that there were some intramolecular and intermolecular interactions among different higher-order structures during the heating process. This study provides a theoretical basis for the development and utilization of jellyfish collagen.