Carbamylation of Cysteine: A Potential Artifact in Peptide Mapping of Hemoglobins in the Presence of Urea

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• 作者：Lippincott ; Julie ; Apostol ; Izydor
• 刊名：Analytical Biochemistry
• 出版年：1999
• 出版时间：February 1, 1999
• 年：1999
• 卷：267
• 期：1
• 页码：57-64
• 全文大小：110 K

文摘

Peptide mapping is a useful technique for identifying posttranslational modifications. However, sometimes artifacts can be introduced during the mapping procedure which can be misleading in identifying the origin and nature of the modifications. During peptide mapping of unalkylated hemoglobins withStaphylococcus aureusV8 proteinase, we found a significant level of carbamylated cysteines. Carbamylation was not detected if recombinant human hemoglobin (rHb1.1) was alkylated prior to digestion. Our experiments indicated that this modification was an artifact of the digestion procedure in which the slightly acidic conditions promoted the reaction of cysteine sulfhydryls with residual cyanate derived from urea. Carbamylmercaptans were found to be stable under acidic conditions but were unstable in base. The extent of cysteine carbamylation can be moderated by the use of scavengers.