Protocol

Cleavage at Met-X Bonds by Cyanogen Bromide

This protocol was adapted from "Peptide Mapping and Sequence Analysis of Gel-Resolved Proteins," Chapter 7, in Proteins and Proteomics (ed. Simpson). Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, USA, 2003.

INTRODUCTION

Selective cleavage of a protein by cyanogen bromide generates a small number of relatively large peptide fragments. This protocol describes protein cleavage with cyanogen bromide, using ~100-fold molar excess of cyanogen bromide over the methionine. The reaction is performed under mild acidic conditions (e.g., 70% formic acid), under nitrogen, and in the dark. All reagents are volatile and can be readily removed by lyophilization.