Quantitative Synthesis of Genetically Encoded Glycopeptide Libraries Displayed on M13 Phage

Phage display is a powerful technology that enables the
discovery
of peptide ligands for many targets. Chemical modification of phage
libraries have allowed the identification of ligands with properties
not encountered in natural polypeptides. In this report, we demonstrated
the synthesis of 2 × 108 genetically encoded glycopeptides
from a commercially available phage-displayed peptide library (Ph.D.-7)
in a two-step, one-pot reaction in <1.5 h. Unlike previous reports,
we bypassed genetic engineering of phage. The glycan moiety was introduced via an oxime ligation following oxidation of an N-terminal Ser/Thr; these residues are present in the peptide
libraries at 20–30% abundance. The construction of libraries
was facilitated by simple characterization, which directly assessed
the yield and regioselectivity of chemical reactions performed on
phage. This quantification method also allowed facile yield determination
of reactions in 109 distinct molecules. We envision that
the methodology described herein will find broad application in the
synthesis of custom chemically modified phage libraries.

噬菌体展示（phage display）是一项可用于发现众多靶点肽配体的强大技术。对噬菌体文库进行化学修饰，已可鉴定出天然多肽中未曾出现的具有特定性质的配体。在本研究中，我们证实可通过两步一锅法反应，在1.5小时以内从商业化有售的噬菌体展示肽文库（Ph.D.-7）中合成2×10⁸个基因编码的糖肽。与既往研究不同，本研究无需对噬菌体进行基因工程改造：通过对N端丝氨酸/苏氨酸（Ser/Thr）进行氧化后，利用肟连接（oxime ligation）反应引入糖基部分，这类残基在肽文库中的丰度为20%~30%。简便的表征手段可助力文库构建，该表征可直接评估噬菌体表面化学反应的产率与区域选择性。此定量方法还可便捷测定10⁹种不同分子的反应产率。我们认为本文所述方法将在定制化学修饰噬菌体文库的合成领域获得广泛应用。