Okayama Prefectural Technology Center for Agriculture, Forestry and Fisheries, Research Institute for Biological Sciences (RIBS), 7549-1 Kibichuo-cho, Kaga-gun, Okayama, 716-1241, Japan.
Org Biomol Chem. 2011 Apr 21;9(8):2943-51. doi: 10.1039/c0ob01090a. Epub 2011 Mar 4.
The reducing tetrasaccharide TMG-chitotriomycin (1) is an inhibitor of β-N-acetylglucosaminidase (GlcNAcase), produced by the actinomycete Streptomyces anulatus NBRC13369. The inhibitor shows a unique inhibitory spectrum, that is, selectivity toward enzymes from chitin-containing organisms such as insects and fungi. Nevertheless, its structure-selectivity relationship remains to be clarified. In this study, we conducted a structure-guided search of analogues of 1 in order to obtain diverse N,N,N-trimethylglucosaminium (TMG)-containing chitooligosaccharides. In this approach, the specific fragmentation profile of 1 on ESI-MS/MS analysis was used for the selective detection of desired compounds. As a result, two new analogues, named TMG-chitomonomycin (3) and TMG-chitobiomycin (2), were obtained from a culture filtrate of 1-producing Streptomyces. Their enzyme-inhibiting activity revealed that the potency and selectivity depended on the degree of polymerization of the reducing end GlcNAc units. Furthermore, a computational modeling study inspired the inhibitory mechanism of TMG-related compounds as a mimic of the substrate in the Michaelis complex of the GH20 enzyme. This study is an example of the successful application of a MS/MS experiment for structure-guided isolation of natural products.
TMG-壳三霉素（1）是一种来源于链霉菌属放线菌 NBRC13369 的β-N-乙酰氨基葡萄糖苷酶（GlcNAcase）抑制剂，它是一种四糖还原物。该抑制剂具有独特的抑制谱，即对来自含甲壳质的生物体（如昆虫和真菌）的酶具有选择性。然而，其结构选择性关系仍需阐明。在本研究中，我们进行了 1 的结构导向搜索，以获得多种含有 N,N,N-三甲基葡萄糖铵（TMG）的壳寡糖类似物。在这种方法中，1 在 ESI-MS/MS 分析中的特定碎裂谱被用于对所需化合物进行选择性检测。结果，从产生 1 的链霉菌的培养滤液中获得了两种新的类似物，分别命名为 TMG-壳霉素（3）和 TMG-壳二霉素（2）。它们的酶抑制活性表明，效力和选择性取决于还原端 GlcNAc 单元的聚合度。此外，计算建模研究启发了 TMG 相关化合物作为 GH20 酶米氏复合体中底物类似物的抑制机制。本研究是 MS/MS 实验成功应用于基于结构的天然产物分离的一个范例。
