Modification of poly-L-lysine by treatment with 1,1-ethylene-bis(1-nitrosourea) in vitro

N6-(Carbamoyl)-L-lysine (CA-Lys), N6-(2-imidazolidinone-N-carbonyl)-L-lysine (INC-Lys), and N6-(2-hydroxyethylcarbamoyl)-L-lysine (HEC-Lys) were synthesized. The radioactive products obtained from enzymatic hydrolysates of polylysine that had been reacted with 1,1'ethylene-bis(1-nitrosourea) (EBNU) [carbonyl-14C] and EBNU [ethylene-14C] coincided with the authentic samples of CA-Lys, INC-Lys, and HEC-Lys on thin-layer chromatography. The main product was CA-Lys and the amounts of other products, such as INC-Lys and HEC-Lys, were extremely small. CA-Lys was also isolated and identified from among the reaction products of EBNU and N1-tert-butyloxycarbonyl-L-lysine. These results demonstrate that EBNU carbamoylates polylysine at the N6-amino group of lysyl residues via various kinds of carbamoylating moieties derived from EBNU.