Nuclear magnetic resonance study of the binding of fluoride ions to carboxypeptidase A

G. Navon*, R. G. Shulman, B. J. Wyluda, T. Yamane

*Corresponding author for this work

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The single zinc atom of carboxypeptidase A has been replaced by manganese to form CPA(Mn) following the method of Coleman & Vallee (1960). Fluoride ions have been shown not to inhibit the enzymic activity of CPA(Mn) and we have studied the broadening of the 19F nuclear magnetic resonance caused by interactions with the paramagnetic manganese. From the strength of the interaction we conclude that fluoride can bind directly to the manganese in the enzyme without affecting either the enzymic activity or the interactions of the manganese with the water protons. The inhibitor β-phenylpropionate removed the 19F broadening by CPA(Mn). The same inhibition constant described this reduction of broadening in the fluoride solutions and the reduction of enzymic activity in the chloride and fluoride solutions of CPA(Mn). These results, in conjunction with our previous nuclear magnetic resonance studies of the water protons, which showed there was one (or more) water ligand of the metal, mean that if the manganese in CPA(Mn) has three protein ligands, as the X-ray crystal structure shows for zinc in CPA(Zn), then the total number of metal ligands is five or more.

Original languageEnglish
Pages (from-to)15-30
Number of pages16
JournalJournal of Molecular Biology
Issue number1
StatePublished - 14 Jul 1970
Externally publishedYes


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