Energetic Basis for Inhibition of Calcium Phosphate Biomineralization by Osteopontin

© 2017 American Chemical Society. Calcium oxalate kidney stones form attached to Randall's plaques (RP), calcium phosphate (Ca-P) deposits on the renal papillary surface. Osteopontin (OPN) suppresses crystal growth in the complex process of urinary stone formation, but the inhibitory role of ac...

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Main Authors: Li, M., Wang, L., Putnis, Christine
Format: Journal Article
Published: American Chemical Society 2017
Online Access:http://hdl.handle.net/20.500.11937/55153
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author Li, M.
Wang, L.
Putnis, Christine
author_facet Li, M.
Wang, L.
Putnis, Christine
author_sort Li, M.
building Curtin Institutional Repository
collection Online Access
description © 2017 American Chemical Society. Calcium oxalate kidney stones form attached to Randall's plaques (RP), calcium phosphate (Ca-P) deposits on the renal papillary surface. Osteopontin (OPN) suppresses crystal growth in the complex process of urinary stone formation, but the inhibitory role of active domains of OPN involved in the initial formation of the RPs attached to epithelial cells has yet to be clarified. Here we demonstrate the thermodynamic basis for how OPN sequences regulate the onset of Ca-P mineral formation on lipid rafts as a model membrane. We first quantify the kinetics of hydroxyapatite (HAP) nucleation on membrane substrates having liquid-condensed (LC) and liquid-expanded (LE) phases using in situ atomic force microscopy (AFM). We find that rates are sequence-dependent, and the thermodynamic barrier to nucleation is reduced by minimizing the interfacial free energy ?. Combined with single-molecule determination of the binding energy (?G B ) of the OPN peptide segments adsorbed to the HAP (100) face, we show a linear relationship of ? and ?G B , suggesting that the increase in the nucleation barriers correlates with strong peptide-crystal nuclei binding. These findings reveal fundamental energetic clues for inhibition of membrane-mediated nucleation by sequence motifs and subdomains within the OPN protein through spatial location of charged moieties and provide insight connecting peripheral cell membranes to pathological mineralization. (Graph Presented).
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spelling curtin-20.500.11937-551532017-09-13T16:10:18Z Energetic Basis for Inhibition of Calcium Phosphate Biomineralization by Osteopontin Li, M. Wang, L. Putnis, Christine © 2017 American Chemical Society. Calcium oxalate kidney stones form attached to Randall's plaques (RP), calcium phosphate (Ca-P) deposits on the renal papillary surface. Osteopontin (OPN) suppresses crystal growth in the complex process of urinary stone formation, but the inhibitory role of active domains of OPN involved in the initial formation of the RPs attached to epithelial cells has yet to be clarified. Here we demonstrate the thermodynamic basis for how OPN sequences regulate the onset of Ca-P mineral formation on lipid rafts as a model membrane. We first quantify the kinetics of hydroxyapatite (HAP) nucleation on membrane substrates having liquid-condensed (LC) and liquid-expanded (LE) phases using in situ atomic force microscopy (AFM). We find that rates are sequence-dependent, and the thermodynamic barrier to nucleation is reduced by minimizing the interfacial free energy ?. Combined with single-molecule determination of the binding energy (?G B ) of the OPN peptide segments adsorbed to the HAP (100) face, we show a linear relationship of ? and ?G B , suggesting that the increase in the nucleation barriers correlates with strong peptide-crystal nuclei binding. These findings reveal fundamental energetic clues for inhibition of membrane-mediated nucleation by sequence motifs and subdomains within the OPN protein through spatial location of charged moieties and provide insight connecting peripheral cell membranes to pathological mineralization. (Graph Presented). 2017 Journal Article http://hdl.handle.net/20.500.11937/55153 10.1021/acs.jpcb.7b04163 American Chemical Society restricted
spellingShingle Li, M.
Wang, L.
Putnis, Christine
Energetic Basis for Inhibition of Calcium Phosphate Biomineralization by Osteopontin
title Energetic Basis for Inhibition of Calcium Phosphate Biomineralization by Osteopontin
title_full Energetic Basis for Inhibition of Calcium Phosphate Biomineralization by Osteopontin
title_fullStr Energetic Basis for Inhibition of Calcium Phosphate Biomineralization by Osteopontin
title_full_unstemmed Energetic Basis for Inhibition of Calcium Phosphate Biomineralization by Osteopontin
title_short Energetic Basis for Inhibition of Calcium Phosphate Biomineralization by Osteopontin
title_sort energetic basis for inhibition of calcium phosphate biomineralization by osteopontin
url http://hdl.handle.net/20.500.11937/55153