Using Chemical Synthesis To Study and Apply Protein Glycosylation

Abstract

Protein glycosylation is one of the most common post-translational modifications and can influence many properties of proteins. Abnormal protein glycosylation can lead to protein malfunction and serious disease. While appreciation of glycosylation's importance is growing in the scientific community, especially in recent years, a lack of homogeneous glycoproteins with well-defined glycan structures has made it difficult to understand the correlation between the structure of glycoproteins and their properties at a quantitative level. This has been a significant limitation on rational applications of glycosylation and on optimizing glycoprotein properties. Through the extraordinary efforts of chemists, it is now feasible to use chemical synthesis to produce collections of homogeneous glycoforms with systematic variations in amino acid sequence, glycosidic linkage, anomeric configuration, and glycan structure. Such a technical advance has greatly facilitated the study and application of protein glycosylation. This Perspective highlights some representative work in this research area, with the goal of inspiring and encouraging more scientists to pursue the glycosciences.

Protein Glycoengineering: An Approach for Improving Protein Properties

“…Unlike many other methods, organic synthesis enables the modification of glycoprotein structures at the atomic level. In theory, it could allow scientists to prepare glycoforms containing any number of glycosylation sites and any type of glycan structures that are required for protein glycoengineering research (Price et al, 2012 ; Chaffey et al, 2018 ).…”

“…Using chemical approaches, two research groups were able to develop new guidelines for N- and O-linked glycoengineering of proteins (Chaffey et al, 2018 ). In their work, Price et al ( 2012 ) provided a theoretical principle to guide the design of protein N-glycoengineering, which stated that “incorporating the enhanced aromatic sequons into appropriate reverse turn types within proteins should enhance the well-known pharmacokinetic benefits of N-glycosylation-based stabilization by lowering the population of protease-susceptible unfolded and aggregation-prone misfolded states”.…”

“…By systematically studying the effects of O-linked glycans on the properties of a family 1 carbohydrate binding module, Patrick et al established a guideline for protein O-glycoengineering, which stated that “O-linked glycoforms with better overall properties can be generated by collaboratively varying glycan structures and adjacent amino acids within unstructured regions that are important for biological function and/or susceptible to proteolytic cleavage and other undesired degradation reactions” (Chaffey et al, 2018 ). The validity of this guideline was confirmed by the glycoengineering study of a therapeutic protein, human insulin.…”

Chemical biology of glycoproteins: From chemical synthesis to biological impact

“…Wang et al, 2013). Similar to the studies of other biopolymers like nucleic acids and proteins, the effects of glycosylation are expected to be precisely established by comparing the properties of a series of representative glycoforms with systematically varied glycans (P. K. Chaffey, Guan, Li, & Tan, 2018).…”

Just a spoonful of sugar: Short glycans affect protein properties and functions

“…At the same time, the increasing rate of approval of glycoprotein therapeutics has fostered the research in the field, giving further impulse to the discovery of new preparation methods and to the studies on the effects of glycosylation on protein properties and functions, thus generating a virtuous circle. Recent reviews describe very well the great advances in the field, particularly in the synthesis of N‐linked glycoproteins carrying complex antennary structures . Moreover, various efficient methodologies for the preparation of homogeneous O‐linked glycopeptides and glycoproteins have been recently developed, furnishing useful tools for biological studies and for potential therapeutic applications, such as cancer vaccines .…”