TY - JOUR
T1 - Mechanism of inhibition of calcium oxalate crystal growth by an osteopontin phosphopeptide
AU - Hug, Susanna
AU - Grohe, Bernd
AU - Jalkanen, Jari
AU - Chan, Brian
AU - Galarreta, Betty
AU - Vincent, Krista
AU - Lagugné-Labarthet, Franois
AU - Lajoie, Gilles
AU - Goldberg, Harvey A.
AU - Karttunen, Mikko
AU - Hunter, Graeme K.
PY - 2012/1/28
Y1 - 2012/1/28
N2 - Osteopontin (OPN) inhibits the nucleation and/or growth of several biominerals, including hydroxyapatite (HA) and calcium oxalate monohydrate (COM), and is thought to function in the prevention of soft-tissue calcification. In previous studies, pOPAR, a peptide corresponding to amino acids 65-80 of rat bone OPN (pSHDHMDDDDDDDDDGD), was shown to be a potent inhibitor of HA crystal growth. We now show that formation of COM in the presence of this peptide results in plate-shaped crystals with rounded ends and scalloped {100} faces. Measurement of crystal dimensions revealed that the pOPAR inhibits growth of COM faces in the order {100} > {121} > {010}. Crystal growth inhibitors are believed to act by adsorbing to growth steps, sites at which lattice-ion addition is energetically favoured. To test this hypothesis, we performed molecular dynamics (MD) simulations of pOPAR adsorption to {121} steps on a {100} face and {121} steps on an {010} face. In the former case, the peptide adsorbs to the {100} (terrace) plane in preference to the {121} (riser) plane; in the latter, the peptide adsorbs to the {121} (riser) plane in preference to the {010} (terrace) plane. These studies represent the first use of MD to study the interaction between an inhibitor and crystal steps. Contrary to the prevailing belief that crystal growth inhibitors adsorb to both lattice planes of a step, we show that pOPAR interacts preferentially to either the terrace or the riser, depending on which is more cationic.
AB - Osteopontin (OPN) inhibits the nucleation and/or growth of several biominerals, including hydroxyapatite (HA) and calcium oxalate monohydrate (COM), and is thought to function in the prevention of soft-tissue calcification. In previous studies, pOPAR, a peptide corresponding to amino acids 65-80 of rat bone OPN (pSHDHMDDDDDDDDDGD), was shown to be a potent inhibitor of HA crystal growth. We now show that formation of COM in the presence of this peptide results in plate-shaped crystals with rounded ends and scalloped {100} faces. Measurement of crystal dimensions revealed that the pOPAR inhibits growth of COM faces in the order {100} > {121} > {010}. Crystal growth inhibitors are believed to act by adsorbing to growth steps, sites at which lattice-ion addition is energetically favoured. To test this hypothesis, we performed molecular dynamics (MD) simulations of pOPAR adsorption to {121} steps on a {100} face and {121} steps on an {010} face. In the former case, the peptide adsorbs to the {100} (terrace) plane in preference to the {121} (riser) plane; in the latter, the peptide adsorbs to the {121} (riser) plane in preference to the {010} (terrace) plane. These studies represent the first use of MD to study the interaction between an inhibitor and crystal steps. Contrary to the prevailing belief that crystal growth inhibitors adsorb to both lattice planes of a step, we show that pOPAR interacts preferentially to either the terrace or the riser, depending on which is more cationic.
UR - http://www.scopus.com/inward/record.url?scp=84855458785&partnerID=8YFLogxK
U2 - 10.1039/c1sm06232h
DO - 10.1039/c1sm06232h
M3 - Article
AN - SCOPUS:84855458785
SN - 1744-683X
VL - 8
SP - 1226
EP - 1233
JO - Soft Matter
JF - Soft Matter
IS - 4
ER -