A dihedral angle-vicinal proton coupling constant correlation for the α–β bond of amino acid residues

A coupling constant-dihedral angle correlation for the H? Cα? Cβ? H system of amino acid residues in peptides has been derived from a set of model compounds covering the full range of dihedral angles. The expression obtained, J = 11.0 cos₂ θ ?1.4 cos θ + 1.6 sin₂θ, is close to those already used in pmr studies of peptide conformation, and provides a firmer foundation for them. A factor limiting the precision of this and other “Karplus relations” is illustrated.     

Effect of Potassium Supplements on the Exchangeable Potassium in Chronic Heart Disease

A study of the effect of additional oral potassium on the low body potassium of seven patients with severe valvular heart disease showed that the potassium supplements were retained. After one month''s treatment the exchangeable potassium was significantly increased, but the predicted value was not reached in any of the patients. There was no significant change in plasma potassium. These results suggest that it is of benefit to increase the dose of oral potassium for at least one month preoperatively in patients undergoing cardiac surgery.