Oligosaccharyl transferase (OT) is the enzyme responsible for asparagine-linked glycosylation in the lumen of the endoplasmic reticulum, which is a subcellular compartment within eukaryotic cells. Inhibition of this enzyme within a cellular environment would provide a valuable investigative tool for glycobiology. Due to the limitations of peptides, none of the existing peptide-based inhibitors of OT demonstrate activity in cell-based enzyme assays. We report herein the design, synthesis and preliminary biological characterization of a family of peptidomimetics that inhibit OT with Ki values in the nanomolar range. The hexapeptide Bz-Dab-Ala-Thr-Val-Thr-Nph-NH2
(Ki
= 69 nM) was used as the prototype for the design of bioavailable inhibitors. Several aminobenzoic acid spacer groups were evaluated as potential isosteres of the Val-Thr dipeptide unit and the peptidomimetic incorporating 3-aminobenzoic acid proved to inhibit OT with similar potency to the parent compound (Ki
= 84 nM). Further modifications explored the effects of size, hydrophobicity and conformational rigidity on enzyme affinity. This study yielded a family of potent non-peptidic inhibitors that are viable candidates for the in vivo inhibition of OT.
寡糖基转移酶 (OT) 是负责内质网腔内天冬酰胺连接糖基化的酶,内质网是真核细胞内的亚细胞区室。在细胞环境中抑制这种酶将为糖
生物学提供有价值的研究工具。由于肽的局限性,现有的基于肽的 OT
抑制剂都没有在基于细胞的酶测定中表现出活性。我们在此报告了一系列
肽模拟物的设计、合成和初步
生物学表征,该类
肽模拟物可抑制 OT,Ki 值在纳摩尔范围内。六肽 Bz-Dab-Ala-Thr-Val-Thr-Nph-NH2
(基
= 69 nM)用作
生物可利用
抑制剂设计的原型。几个
氨基
苯甲酸间隔基团被评估为 Val-Thr 二肽单元的潜在等排体,并且掺入 3-
氨基
苯甲酸的
肽模拟物被证明可以抑制 OT,其效力与母体化合物相似 (Ki
= 84 nM)。进一步的修饰探讨了尺寸、疏
水性和构象刚性对酶亲和力的影响。这项研究产生了一系列有效的非肽
抑制剂,它们是体内 OT 抑制的可行候选者。