Douglass J F, Jaya N N, Vedvick T S, Reed S G, Zhang Y, Carter D
Department of Antigen Discovery, Corixa Corp, Seattle, Washington 98104, USA.
J Protein Chem. 2001 Oct;20(7):571-6. doi: 10.1023/a:1013373230660.
Interpretation of deglycosylation studies relies heavily on the absence of modifications to the polypeptide chain. We have found that by using a common chemical deglycosylation technique, one can effect at least three changes in a peptide's structure: methylation, isomerization, and ring formation. It was determined that the conditions of chemical deglycosylation introduce a +14 Da shift in the masses of our model peptides, RKDVY, RKEVY, and horseradish peroxidase. This shift is localized to acidic functional groups and is interpreted as methylation of the free carboxylates in our models. An additional shift in mass of -18 Da is found in the model peptide RKDVY consistent with the loss of water associated with succinimide ring formation in this peptide. Chemical treatment induced isomerization of aspartyl residues to isoaspartyl residues in another model peptide, tetragastrin. These results indicate that one should use caution when interpreting the results of chemical deglycosylation experiments.
去糖基化研究的解读在很大程度上依赖于多肽链未发生修饰。我们发现，通过使用一种常见的化学去糖基化技术，能够使肽的结构至少发生三种变化：甲基化、异构化和环化。经测定，化学去糖基化条件会使我们的模型肽RKDVY、RKEVY和辣根过氧化物酶的质量发生+14 Da的偏移。这种偏移定位于酸性官能团，在我们的模型中被解释为游离羧酸盐的甲基化。在模型肽RKDVY中发现了另外-18 Da的质量偏移，这与该肽中与琥珀酰亚胺环形成相关的水的损失一致。化学处理导致另一种模型肽四肽胃泌素中天冬氨酸残基异构化为异天冬氨酸残基。这些结果表明，在解读化学去糖基化实验结果时应谨慎。
