Molecular Pharmacology, Vol 11, 119-125, Copyright © 1975 by the American Society for Pharmacology and Experimental Therapeutics

A Nuclear Magnetic Resonance Study of the Interaction between Vanomycin and Acetyl-D-alanyl-D-alanine in Aqueous Solution

¹ Division of Molecular Pharmacology, National Institute for Medical Research, Mill Hill, London, N.W.7, England

The association between vancomycin and acetyl-D-alanyl-D-alanine has been studied by nuclear magnetic resonance spectroscopy. The proton resonances of the three methyl groups in the peptide are all shifted upfield in the complex, probably because the methyl groups are bound in the proximity of aromatic rings in vancomycin. An analysis of binding as a function of pH showed that while the most stable complex is formed between the peptide anion and the vancomycin cation, weaker complexes are formed between uncharged peptide and vancomycin cation and between peptide anion and uncharged vancomycin. The interacting cationic group in vancomycin was identified as the NH₂-terminal N-methylleucine. The peptide proton chemical shifts are unaffected by temperature, but the acetyl shift is decreased at high pH by ionization of the N-methylleucine or vancosamine. In aglucovancomycin, the binding constant is weaker and all the chemical shifts in the bound complex are reduced.

Note:
ACKNOWLEDGMENT We are grateful to Lilly Research Centre, Ltd., for a generous supply of vancomycin hydrochloride.