Sinha R K, Rosenthal R S
Infect Immun. 1980 Sep;29(3):914-25. doi: 10.1128/iai.29.3.914-925.1980.
Previous analysis of soluble peptidoglycan (PG) fragments released by exponentially growing gonococci implicated the combined action of both hexosaminidase and amidase activities in PG turnover. Current studies further characterized PG fragments which were labeled in the glycan with D-glucosamine and in the peptide moiety with meso-diaminopimelic acid of L- and D-alanine. Labeled PG fragments were isolated by gel filtration and characterized on the bases of (i) KD values, (ii) free amino group analysis using fluorodinitrobenzene, (iii) borohydride reduction, (iv) alkali-catalyzed beta-elimination, (v) paper chromatography in various solvents, (vi) electrophoretic mobility at various pH values, (vii) digestibility by Charonia lampas glycosidases, and (viii) content of labeled D- and L-alanine. A set of well-characterized PG fragments was used as standards. The monomer fraction (the major extracellular product) was found to contain two components. Most (about 80%) appeared to be N-acetylglucosaminyl-beta-1 leads to 4-1,6-anhydro-N-acetylmuramyl-L-ala-D-glu-meso-diaminopimelic acid; the remainder was the corresponding disaccharide tetrapeptide containing a C-terminal D-alanine. An unusual feature of these products was the presence of the anhydro-muramyl (non-reducing) ends, reflecting the activity of a gonococcal transglycosylase, and the near absence of products containing detectable reducing ends. Otherwise, the structures of the monomer fragments were typical of those expected for a gram-negative bacterium (chemotype I). The corresponding peptide-cross-linked dimer and the free disaccharide also contained nonreducing ends, exclusively. Free peptides (products of amidase activity) consisted of both tripeptide and tetrapeptide. In summary, all gonococci examined appear to possess an unusual transglycosylase activity which contributes to the release of soluble PG fragments containing nonreducing, anhydro-muramyl ends. The release of these fragments in vivo might be a unique aspect of gonococci-host interactions.
先前对指数生长的淋球菌释放的可溶性肽聚糖（PG）片段的分析表明，己糖胺酶和酰胺酶活性共同作用于PG的周转。目前的研究进一步对PG片段进行了表征，这些片段在聚糖中用D-葡萄糖胺标记，在肽部分用L-和D-丙氨酸的内消旋二氨基庚二酸标记。通过凝胶过滤分离标记的PG片段，并基于以下方面进行表征：（i）KD值；（ii）使用氟二硝基苯的游离氨基分析；（iii）硼氢化还原；（iv）碱催化的β-消除；（v）在各种溶剂中的纸色谱法；（vi）在各种pH值下的电泳迁移率；（vii）被华丽巨蚌糖苷酶的消化率；（viii）标记的D-和L-丙氨酸的含量。一组特征明确的PG片段用作标准品。单体部分（主要的细胞外产物）被发现含有两种成分。大多数（约80%）似乎是N-乙酰葡糖胺基-β-1导致4-1,6-脱水-N-乙酰胞壁酰-L-ala-D-glu-内消旋二氨基庚二酸；其余部分是含有C端D-丙氨酸的相应二糖四肽。这些产物的一个不寻常特征是存在脱水胞壁酰（非还原）末端，这反映了淋球菌转糖基酶的活性，并且几乎不存在含有可检测还原末端的产物。否则，单体片段的结构是革兰氏阴性细菌（化学型I）预期的典型结构。相应的肽交联二聚体和游离二糖也仅含有非还原末端。游离肽（酰胺酶活性的产物）由三肽和四肽组成。总之，所有检测的淋球菌似乎都具有一种不寻常的转糖基酶活性，这有助于释放含有非还原、脱水胞壁酰末端的可溶性PG片段。这些片段在体内的释放可能是淋球菌与宿主相互作用的一个独特方面
