β Scribed by Ushio Sakaguchi; Kaiji Morito; Hayami Yoneda
No coin nor oath required. For personal study only.
&oton magnetic resonance spectra were measured for some cobalt(M) amino acid complexes in D20 and in ammonia solution [I ] . In carboxylato coordinated [Co(NHJ500CCH(R)NHS] 3' compounds in DzO, the chsmical shifts of amino acid hydrogens are close to those of the free amino acid in the dipolar form, whereas upon deprotonation at NH3 they are rather close to those of the anionic form of the free amino acid. The side-chain conformation of amino acid ligands has been deduced, where possible, from the three bond spin-spin coupling constants between the a-and pprotons. Chelation caused a side-chain conformational change, which seems to be brought about by the steric repulsion between the carbonyl oxygen and the a-substituent (R) of amino acid. For phenylalanine complexes, the effect of coordination upon side-chain rotamer distribution is greater than the effect of solution pH for the free amino acid. In pentaammine(L-histldine)cobalt(III) ion, the long-range coupling between the imidazole C4 hydrogen and only one of the Dhydrogen has been observed, suggesting a restricted rotation about the C&, bond.
π SIMILAR VOLUMES
## Abstract A number of carbonylβbisβ(amino acid esters) have been examined by proton and carbonβ13 nuclear magnetic resonance techniques. All but one of the compounds were synthesized with two chiral centers of likeβconfiguration. In one series, the diastereotopic nonequivalence of isopropyl methy
## Abstract The ^17^O NMR chemical shifts of five enriched amino acids have been measured under strictly controlled conditions of concentration, ionic strength, pH and temperature. The Ξ±, Ξ² and Ξ±, Ξ³ carboxyl resonances of aspartic and glutamic acid, respectively, have been resolved. Line widths wer