THE ORDER OF LITHIUM ION AFFINITIES FOR THE 20 COMMON ALPHA-AMINO-ACIDS - CALCULATION OF ENERGY-WELL DEPTH OF ION-BOUND DINNERS

In an earlier publication it was shown that the kinetic method for det ermination of proton affinities can be satisfactorily explained when t he critical energies for decomposition of the proton-bound dimers are calculated from the Marcus equation. In this work it is shown that the critical energies for decomposition of alkali metal ion-bound dimers also seem to follow the Marcus equation. This supports the application of the kinetic method for measurements of alkali metal-ion affinities of organic molecules. Based on unimolecular decompositions of Li+-bou nd dimers, the order of lithium ion affinity of the common a-amino aci ds has been established as: Arg > His > Gin > Asn > Lys > Trp > Glu > Asp > Tyr > Met > Phe > Thr > Pro > Ser > Ile > Leu > Val > Cys > Ala > Gly.