MOLECULAR MECHANICS CALCULATIONS OF ALPHA -ALANINE AND L-HISTIDINE AND NMR-STUDY OF THEIR LANTHANIDES COMPLEXES

Molecular Mechanics was applied to obtain the molecular structure of t he alpha-alanine and L-histidine in solution. The molecular structures of their lanthanide complexes which were obtained by simulating the p seudo-contact shifts of the complexes are presented. For alpha-alanine , the lanthanides (Ce3+ is similar to Nd3+) complex with one oxygen at om and one nitrogen atom; the lanthanides (Sm3+ is similar to Yb3+) co mplex with two oxygen atoms. For L-histidine, the lanthanides (Ce3+ is similar to U3+) complex with two oxygen atoms and one nitrogen atom; the lanthanides (Tb3+ is similar to Yb2+) complex with two oxygen atom s. The pH dependences of the molecular structures of the complexes wer e discussed.