| Abstract: | Ab initio SCF computations indicate that the formation of an adduct of glyoxal to the guanidinium ion occurs in two steps. The first addition should occur on an NH2 group, rather than on NHCH3, and the formation of an unsymmetrical adduct IV is competitive and may be even favored over that of the symmetrical adduct III suggested by Takahashi. The barrier for that reaction is higher than for a similar reaction with guanine. The formation of a Schiff base between glyoxal and the guanidinium ion is disfavored because of the large endothermicity calculated for the process, much larger than that predicted for Schiff base formation with simple neutral or protonated amines. |
