悬铃木细胞外木葡聚糖九糖重复单元上O-乙酰基取代基的位置

Location of the O-acetyl substituents on a nonasaccharide repeating unit of sycamore extracellular xyloglucan.

作者信息

York W S, Oates J E, van Halbeek H, Darvill A G, Albersheim P, Tiller P R, Dell A

机构信息

Complex Carbohydrate Research Center, University of Georgia, Athens 30613.

出版信息

Carbohydr Res. 1988 Feb 15;173(1):113-32. doi: 10.1016/s0008-6215(00)90807-3.

DOI:10.1016/s0008-6215(00)90807-3

PMID:3356024

Abstract

The locations of the O-acetyl substituents on the major nonasaccharide repeating unit of the xyloglucan isolated from sycamore extracellular polysaccharides were determined by a combination of analytical methods, including f.a.b.-m.s. and 1H-n.m.r. spectroscopy. The O-2-linked-beta-D-galactosyl residue of the nonasaccharide was found to be the dominant site of O-acetyl substitution. Both mono-O-acetylated and di-O-acetylated beta-D-galactosyl residues were detected. The degree of O-acetylation of the beta-D-galactosyl residue, was estimated by 1H-n.m.r. spectroscopy to be 55-60% at O-6, 15-20% at O-4, and 20-25% at O-3. 1H-n.m.r. spectroscopy also indicated that approximately 50% of the beta-D-galactosyl residues are mono-O-acetylated, 25-30% are di-O-acetylated, and 20% are not acetylated.

摘要

通过包括快原子轰击质谱（f.a.b.-m.s.）和核磁共振氢谱（1H-n.m.r.）光谱在内的多种分析方法，确定了从悬铃木细胞外多糖中分离出的木葡聚糖主要九糖重复单元上O-乙酰基取代基的位置。发现九糖中O-2连接的β-D-半乳糖基残基是O-乙酰基取代的主要位点。检测到了单-O-乙酰化和二-O-乙酰化的β-D-半乳糖基残基。通过核磁共振氢谱光谱估计，β-D-半乳糖基残基的O-乙酰化程度在O-6位为55 - 60%，在O-4位为15 - 20%，在O-3位为20 - 25%。核磁共振氢谱光谱还表明，大约50%的β-D-半乳糖基残基是单-O-乙酰化的，25 - 30%是二-O-乙酰化的，20%没有乙酰化。