N-substituted (β-D-galactopyranosylmethyl)amines as reversible inhibitors of β-D-galactosidase

Abstract Through the use of a series of N -substituted (β- d -galactopyranosylmethyl)amines (βGal-CH 2 NHR) and the corresponding N -substituted C -(β- d -galactopyranosyl)formamides (βGal-CO-NHR), it has been determined that the inhibitor binding constant is influenced more by the p K a of the amine group than by the nature of the hydrophobic group. It is concluded thatthe compounds that are the best inhibitors are those which allow proton donation in the active site to form an ion pair (βGal-CH 2 NHR + AH → βGal-CH 2 NH 2 R + + A − .