The nature of the Ln3+ —angiotensin II complex. A 13C nmr study of the binding of Yb3+ to angiotensin ii

Abstract The nature of the Yb 3+ -angiotensin II complex is examined by 13C nuclear magnetic resonance. The ytterbium-induced shifts of most resonances are observed to be strongly dependent on p D , while a few are observed to be largely independent of p D . These observations are shown to be consistent with stepwise binding of the lanthanide ion to the carboxylates of aspartic acid and the C-terminus.