Methods for producing isotopically-labelled peptides are provided. Aspects of the method include: contacting a sample including a metabolically tagged protein with a cleavable probe to produce a probe-protein conjugate; separating the probe-protein conjugate from the sample; digesting the probe-protein conjugate to produce a probe-peptide conjugate; and cleaving a cleavable linker to release an isotopically labelled peptide. The method may further include: identifying a predetermined isotopic pattern in a mass spectrum; determining an amino acid sequence of the isotopically labelled peptide; and identifying the site of protein glycosylation based on the determined amino acid sequence. Also provided are cleavable probes for practicing the subject methods, described by the Formula: A-L-(M-Z) where A is an affinity tag, L is a cleavable linker, M is an isotopic label and Z is a chemoselective tag capable of cross-linking a metabolically tagged protein. Compositions and kits for practicing the subject methods are also provided.
提供生产同位素标记肽的方法。该方法的步骤包括:将含有代谢标记蛋白质的样品与可裂解的探针接触以产生探针-蛋白质结合物;将探针-蛋白质结合物与样品分离;消化探针-蛋白质结合物以产生探针-肽结合物;裂解可裂解的连接剂以释放同位素标记的肽。该方法还可以包括:在质谱中识别预定的同位素模式;确定同位素标记的肽的
氨基酸序列;并根据确定的
氨基酸序列确定蛋白质糖基化的位置。还提供了可裂解的探针,用于实施该方法,其由公式A-L-(M-Z)描述,其中A是亲和标记,L是可裂解连接剂,M是同位素标记,Z是具有交联代谢标记蛋白质的
化学选择标记。还提供了用于实施该方法的组合物和工具包。