ABSTRACT
A statistical molecular model for hydrated peptides is used to stimulate the behaviour of various peptide chains in aqueous solution. The reliability of the model is ascertained by the evolution of the characteristic ratio, Cn, for hydrophobic and hydrophilic polypeptide chains, such as, respectively, poly-Ala and poly-Ser. The comparison of computed and experimental properties related to non radiative energy transfer of angiotensin II analogs, assuming that an ensemble of conformers is a satisfactory representation of the state of these molecules in water, provides further support for the model.
Subject(s)
Angiotensin II/analogs & derivatives , Peptides , Amino Acid Sequence , Hydrogen Bonding , Models, Molecular , Structure-Activity RelationshipABSTRACT
The properties related to non-radiative energy transfer of a number of enkephalin analogues with tryptophan substituted for phenylalanine in position 4 and n.m.r. 3JNH-C alpha H coupling constants of corresponding [Phe4]-enkephalin analogues are being derived from semi-empirical conformational energy. The molecules considered contain a glycyl, a D-alanyl or an L-alanyl as second residue; two of the compounds are N-methylated at position 4 or 5. The [Trp4]-enkephalin analogues and the corresponding [Phe4]-enkephalin analogues display nearly parallel affinities in the opiate receptor binding assay (Schiller et al. (1). The comparison of computed and experimental properties shows that an ensemble of conformers is a satisfactory representation of the state of these molecules in water.
