Adsorption of a Statherin Peptide Fragment on the Surface of Nanocrystallites of Hydroxyapatite

Abstract

Statherin is an active inhibitor of calcium phosphate precipitation in the oral cavity. For many studies of the interaction between statherin and hydroxyapatite (HAp), the samples are prepared by a direct mixing of statherin or its fragment with well-crystalline HAp crystals. In this work, the HAp sample is precipitated in the presence of peptide fragment derived from the N-terminal 15 amino acids of statherin (SN-15). The in situ prepared HAp crystallites are nanosized, leading to a significant increase of the peptide amount adsorbed on the HAp surface. The enhancement in NMR sensitivity allows, for the first time, the measurement of a two-dimensional 13C-13C correlation spectrum for a 13C uniformly labeled peptide sample adsorbed on mineral surface. The measurement time is about 18.5 h at a field strength of 7.05 T. Preliminary results suggest that there may exist two different mechanisms for the interaction between SN-15 and HAp. In addition to the one which will cause a conformational change near the N-terminal, SN-15 may also be absorbed on the HAp surface by simple electrostatic interaction, without any significant conformational changes of the peptides.

Roles of Electrostatics and Conformation in Protein-Crystal Interactions

“…Based on their studies on the interaction between a phosphopeptide corresponding to amino acids 93–106 of human OPN and the {100} face of COM, a similar conclusion was reached by Wang et al [26]. Electrostatics has been reported to dominate in the adsorption to HA of peptides of β-casein [36], fibronectin [65] and statherin [66]. Our recent analysis of the effects of urinary proteins and model compounds on calcium oxalate crystal formation also shows that the most potent inhibitors have high negative charge density and high hydrophilicity [67].…”

Hydroxyapatite nanorod and microsphere functionalized with bioactive lactoferrin as a new biomaterial for enhancement bone regeneration

“…The TG-DTG curve of nano-HAP-LF also showed a weight loss at the temperature of 200-500 °C , which is confirmed by the absence of LF in the nano-HA-LF composite material. What's more, as shown in Figure 6a, the nano-HAP was stable at a temperature of up to 1200 °C , and no secondary phase formation was noted on heating over 800-1200 °C [40] . A weight loss of 5.20% was obtained from the nano-HAP TG-DTG curve (Curve 1), while a weight loss of 17.84% was obtained from nano-HAP-LF TG-DTG curve (Curve 2).…”

An in vitro scanning microradiography study of the reduction in hydroxyapatite demineralization rate by statherin‐like peptides as a function of increasing N‐terminal length

“…The other mechanism suggested by C hen et al. (12) is related to simple electrostatic interactions between the peptide and the HA surfaces. The suggestion that statherin has two HA‐binding sites is also in agreement with the thermodynamic studies performed by G oobes et al.…”

“…C hen et al. (12) suggested that there are two types of interactive mechanisms between an N‐terminal 15‐residue statherin‐like peptide and HA. One mechanism is related to the conformational change at K6 (lysine residue) from a helical structure to a random‐coil structure.…”

“…When a longer peptide, identical to the N terminus of statherin (12 residues), was examined, the first six residues of the peptide were found to be in an a-helix conformation that was bound to the HA, with the next six residues continuing in the a-helix but less strongly bound and consequently more flexible (9). Chen et al (12) suggested that there are two types of interactive mechanisms between an N-terminal 15-residue statherin-like peptide and HA. One mechanism is related to the conformational change at K6 (lysine residue) from a helical structure to a random-coil structure.…”