The observed V3 torsional barriers measured by microwave spectroscopy for nine methyl groups attached alpha to peptide bond linkages in five gas-phase biomimetics have been found to differ considerably from one molecule to the next and even depend on the position of substitution, being sensitive to structural changes at the other end of the peptide bond. In the search for an explanation for the...

A particulate preparation obtained from Phoseolus aweus shoots contains an enzyme capable of transferring the 14Clabeled methyl groups from S-adenosyl-L-methionine to the carbozyl groups of polygalacturonic acid, which seems to be present in the same particulate material. The introduction of the methyl ester groups is optimal at pH 6.8 and does not require divalent ions. S-IV-Methyltetrahydrofo...

Molecules which have rotating groups may show coupled motions. As an example, two adjacent methyl groups may exhibit some degree of correlated motion as two wheels in gear. 1 The spectra obtained by traditional single quantum NMR in oriented molecules may sometimes be complicated and difficult to analyze. However, the techniques of multiple quantum (MQ) NMR spectroscopy can yield analyzable spe...