Isolation and Analysis of a Novel Proteoglycan from Zizyphus jujuba cv. Jinsixiaozao
Jin-wei Li1,4*, yi-yong chen2, Shao-dong Ding3 AND LIAN-FU ZHANG1,4
1. School of Food Science and Technology, Jiangnan University, Wuxi 214036, China
2. Department of Biology and Food Engineering, Changshu Institute of Technology, Changshu 215500, China
3. Center of Testing and Analysis, Jiangnan University, Wuxi 214036, China
4. State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214036, China
(Received: June 13, 2006; Accepted: March 1, 2007)
Abstract
Chinese jujube (Zizyphus jujuba Miller) is a well-known oriental medicinal plant that has various biological activities. In this study, a novel water-soluble proteoglycan (ZSG4b) was isolated from Zizyphus jujuba cv. Jinsixiaozao and its effect on the complement system was investigated. ZSG4b was extracted with hot water and purified by DEAE-Sepharose CL-6B and Sepharose CL-6B column chromatography. It was eluted as a single symmetrical narrow peak on high-performance gel-permeation chromatography (HPGPC) and the average molecular weight was estimated to be 1.4 × 105 Da. ZSG4b contained 83.5% glycan and 9.7% protein. Gas chromatography analysis result indicated that the glycan portion of ZSG4b was composed mainly of rhamnose, arabinose, mannose and galactose in a molar ratio of 13.8:4:3:8. It also contains 29% uronic acid as determined by m-hydroxybiphenyl method. The presence of galacturonic acid was estimated by the increase of galactose content in the carboxyl-reduced ZSG4b. The amino acid composition showed that it was rich in aspartic acid, glutamic acid, serine, threonine and leucine; the molar content of these five amino acids constituted 62.8% of the total amino acids. The β-elimination reaction demonstrated that the protein and glycan were linked by O-linkage. ZSG4b exhibited high anti-complement activity which was increased in accordance with the concentration below 120 μg/mL in vitro.
Key words: Zizyphus jujuba cv. Jinsixiaozao, proteoglycan, Fourier transforms infrared spectra, β-elimination reaction, anti-complement activity