NMR investigations of the static and dynamic structures of bisphosphonates on human bone: A molecular model

Sujoy Mukherjee, Yongcheng Song, Eric Oldfield

Research output: Contribution to journalArticle

Abstract

We report the results of an investigation of the binding of a series of bisphosphonate drugs to human bone using 2H, 13C, 15N, and 31P nuclear magnetic resonance spectroscopy. The 31P NMR results show that the bisphosphonate groups bind irrotationally to bone, displacing orthophosphate from the bone mineral matrix. Binding of Pamidronate is well described by a Langmuir-like isotherm, from which we deduce an ∼30-38 Å2 surface area per Pamidronate molecule and a ΔG = -4.3 kcal mol-1. TEDOR of [ 13C3, 15N] Pamidronate on bone shows that the bisphosphonate binds in a gauche [N-C(1)] conformation. The results of 31P as well as 15N shift and cross-polarization measurements indicate that risedronate binds weakly, since it has a primarily neutral pyridine side chain, whereas zoledronate (with an imidazole ring) binds more strongly, since the ring is partially protonated. The results of 2H NMR measurements of side-chain 2H-labeled Pamidronate, alendronate, zoledronate, and risedronate on bone show that all side chains undergo fast but restricted motions. In Pamidronate, the motion is well simulated by a gauche+/gauche- hopping motion of the terminal -CH2-NH3+ group, due to jumps from one anionic surface group to another. The results of double-cross polarization experiments indicate that the NH3+-terminus of pamidronate is close to the bone mineral surface, and a detailed model is proposed in which the gauche side-chain hops between two bone PO43- sites.

Original languageEnglish (US)
Pages (from-to)1264-1273
Number of pages10
JournalJournal of the American Chemical Society
Volume130
Issue number4
DOIs
StatePublished - Jan 30 2008

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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