Reaction of N-methyl-N-nitro-N-nitrosoguanidine with protein: formation of nitroguanido derivatives

When serum albumin is exposed to N-methyl-N′-nitro-N-nitrosoguanidine (NG) one of the main reactions is conversion of ε-amino groups of lysine to nitroguanido groups. This conversion results in a large increase in the extinction coefficient of the protein as well as an increase in electrophoretic mobility (toward the positive pole). The lysine content of the protein is reduced. Enzymatic hydrolysis of NG-treated protein liberates an …