PROTON AFFINITIES OF LYSINE AND HISTIDINE - A THEORETICAL CONSIDERATION OF THE DISCREPANCY BETWEEN EXPERIMENTAL RESULTS FROM THE KINETIC AND BRACKETING METHODS

Ab initio quantum chemical computations in conjunction with semiempiri cal methods have been applied to the proton affinities of the amino ac ids lysine and histidine. The data obtained show that lysine is much m ore basic than histidine. The results reported here agree well with re cent bracketing measurements of the proton affinities but contradict o ther measurements made by the kinetic method. The reason for this disa greement is discussed.