The structure, dynamics, and energetics of protein adsorption—lessons learned from adsorption of statherin to hydroxyapatite

Abstract

Proteins are found to be involved in interaction with solid surfaces in numerous natural events. Acidic proteins that adsorb to crystal faces of a biomineral to control the growth and morphology of hard tissue are only one example. Deducing the mechanisms of surface recognition exercised by proteins has implications to osteogenesis, pathological calcification and other proteins functions at their adsorbed state. Statherin is an enamel pellicle protein that inhibits hydroxyapatite nucleation and growth, lubricates the enamel surface, and is recognized by oral bacteria in periodontal diseases. Here, we highlight some of the insights we obtained recently using both thermodynamic and solid state NMR measurements to the adsorption process of statherin to hydroxyapatite. We combine macroscopic energy characterization with microscopic structural findings to present our views of protein adsorption mechanisms and the structural changes accompanying it and discuss the implications of these studies to understanding the functions of the protein adsorbed to the enamel surfaces.

Binding of chloroquine–conjugated gold nanoparticles with bovine serum albumin

“…The heat of the ligand dilution in the buffer alone was subtracted from the titration data for each experiment. The data were analyzed to determine the binding stoichiometry (N), affinity constant (K a ), and other thermodynamic parameter of the reaction using origin software [30]. Titration of protein with GNP-Chl nanoconjugates was carried out at 25°C.…”

Hydroxylapatite nanoparticles: fabrication methods and medical applications

“…HAp nanoparticles, therefore, have been investigated as a carrier for delivery of drugs such as growth factors [219,220], antibiotics [5,[221][222][223][224][225] and anticancer drugs [5,226,227]. The adsorption/desorption characteristics [44,220,[228][229][230] and conformation changes [230][231][232][233][234][235] of various kinds of proteins (or peptides) on HAp surfaces have been studied. Mukhopadhyay et al [236] recently reported that HAp nanoparticle supplementation increases thermal stability of pectate lyase from Bacillus megaterium, that is, this enzyme can retain high activity at elevated temperatures (up to 90…”

“…Recently, computational (in silico) studies have been gradually progressed to clarify the interaction between proteins (or peptides) and HAp surfaces [237][238][239]. Detailed information on the protein/peptide adsorptions can be found in the original papers or a recent review by Goobes et al [235].…”

“…The greatest motivation behind the use of HAp is to accurately mirror the chemistry of natural minerals. The recent progress in computational analyses for the conformation changes, which alter structure and function at a distant active site, of the proteins interacting with HAp surfaces [235,[237][238][239] will provide a guide for designing nanostructured HAp surfaces to transcend the chemistry of natural minerals. Although nanostructured biomaterials have many potential advantages, it is important to remember that the effects of nanoparticle exposure on human health are not well understood.…”

Experimental characterization of adsorbed protein orientation, conformation, and bioactivity

“…15,17 Some of the methods that can provide information on adsorbed protein orientation and tertiary (and quaternary) structure include fluorescence, [18][19][20][21] time-of-flight secondary-ion mass spectrometry, [22][23][24] nuclear magnetic resonance spectroscopy (NMR), 25,26 and amino acid labeling/mass spectrometry (AAL/MS). [27][28][29][30][31] Methods for the determination of secondary structure of adsorbed proteins include Fourier transform infrared spectroscopy, 32,33 surface enhanced Raman scattering, 34,35 and circular dichroism spectropolarimetry (CD).…”