Intercluster reactions show that (CH3)2S CH2CO2H is a better methyl cation donor than (CH3)3N CH2CO2H

Abstract

The intrinsic methylating abilities of the known biological methylating zwitterionic agents, dimethylsulfonioacetate (DMSA), (CH3) 2S+CH2CO2- (1) and glycine betaine (GB), (CH3)3N+CH 2CO2- (2), have been examined via a range of gas phase experiments involving collision-induced dissociation (CID) of their proton-bound homo- and heterodimers, including those containing the amino acid arginine. The relative yields of the products of methyl cation transfer are consistent in all cases and show that protonated DMSA is a more potent methylating agent than protonated GB. Since methylation can occur at more than one site in arginine, the [M + CH3]+ ion of arginine, formed from the heterocluster [DMSA..