O-糖基化对Enterococcus faecium AS8糖肽结构和抗氧化活性的影响  

Effect of O-glycosylation on structure and antioxidant activity of Enterococcus faecium AS8 glycopeptides

作　　者：李树勋 白英[1] LI Shuxun;BAI Ying(College of Food Science and Engineering,Inner Mongolia Agricultural University,Hohhot 010018,China)

机构地区：[1]内蒙古农业大学食品科学与工程学院,内蒙古呼和浩特010018

出　　处：《食品与发酵工业》2025年第4期145-153,共9页Food and Fermentation Industries

基　　金：国家自然科学基金项目(31760460);内蒙古自治区科技项目(2023YFHH0121)。

摘　　要：该文以屎肠球菌(Enterococcus faecium)AS8的乳发酵液为原料提取糖肽,以粗糖肽提取率为指标,采用单因素及响应面试验对其提取工艺进行了优化,再经凝胶柱层析纯化后得到糖肽(AS8 glycopeptide,AGP),采用SDS-PAGE和高效凝胶渗透色谱(high-performance gel permeationchromatography,HPGPC)对其纯度进行鉴定,使用β-消除法切除AGP中O-糖链得到去糖基化产物(deglycosylated AS8 glycopeptide,dAGP),并对AGP和dAGP进行红外光谱、荧光光谱、扫描电镜、热稳定性及抗氧化活性测定来初步探究O-糖基化对AGP结构和抗氧化活性的影响。结果显示,去糖基化后,AGP部分红外吸收峰强度显著降低,主要二级结构β-折叠减少,内源荧光强度增加,最大发射波长红移,外源最大荧光强度降低,表面疏水性降低,热稳定性降低,微观结构由光滑紧密变得粗糙多孔,ABTS阳离子自由基清除能力增强,DPPH自由基和羟自由基清除能力降低。该研究结果表明O-糖链的去除改变了AGP的抗氧化活性并使其结构稳定性降低。Glycosylation plays a crucial role in the activity and conformation of proteins/peptides.This study utilized the milk fermentation broth of Enterococcus faecium AS8 as a raw material for extracting glycopeptides.The extraction rate of crude glycopeptides was used as a key indicator,and the extraction process was optimized through single factor and response surface experiments.Subsequently,the glycopeptides were purified via gel column chromatography to obtain the AS8 glycopeptide(AGP).AGP was evaluated for purity using SDS-PAGE and HPGPC,followed by the removal of the O-sugar chain in AGP through theβ-elimination method to obtain the deglycosylated AS8 glycopeptide(dAGP).AGP and dAGP were then analyzed using infrared spectroscopy,fluorescence spectroscopy,scanning electron microscopy,thermal stability,and antioxidant activity measurements to preliminarily investigate the impact of O-glycosylation on the structure and antioxidant activity of AGP.Results indicated that deglycosylation led to a significant reduction in the intensity of certain infrared absorption peaks of the AGP,as well as a decrease in the main secondary structureβ-folding.Additionally,there was an increase in endogenous fluorescence intensity,a red-shift in the maximum emission wavelength,and a decrease in the maximum fluorescence intensity of the exogenous source.The surface hydrophobicity was also reduced,along with a decrease in thermal stability.The microstructure changed from smooth and compact to rough and porous.Furthermore,the scavenging capacity of ABTS cationic free radicals was enhanced,while the scavenging capacity of DPPH radicals and·OH scavenging capacity decreased.Overall,these findings suggest that the removal of O-glycosyl chains alters the antioxidant activity of AGP and diminishes its structural stability.

关 键 词：糖肽 去糖基化 结构 抗氧化活性 

分 类 号：TS201.2[轻工技术与工程—食品科学]