Protein seeding of gold nanoparticles and mechanism of glycation sensing.

The plasmon resonance of gold nanoparticles (GNPs) synthesized on a protein template senses formation of advanced glycosylated end products (AGEs). A graded alteration of plasmon resonance (both the peak and intensity are affected) is observed as the glycation progresses. Transmission electron microscopy shows significant shift of the size distribution of GNPs in presence of glycation.

Gold nanoparticle-based tool to study protein conformational variants: implications in hemoglobinopathy.

The size of gold nanoparticles is shown here to gradually decrease if it is allowed to grow on a protein template, and the protein is subjected to unfolding by a nonionic denaturant. The correlation between size of the gold nanoparticle formed and the plasmon frequency observed remains linear, except at stages where protein folding intermediates are formed. Higher population of exposed tyrosine residues, number of sulfhydryl groups of the protein, and the overall exposition of the inner hydrophobic core may lead to the generation of smaller particles.

Compensatory secondary structure alterations in protein glycation.

Glycation, a local covalent interaction, leads to alterations in secondary and tertiary structures of hemoglobin, the changes produced by fructose being more pronounced than those caused by glucose. The Stokes diameter of hemoglobin increases upon glycation from 7 to 14 nm and a concurrent inter-chain cross-linking and heme loss are also observed, particularly in the later stage of glycation. An initial increase of tryptophan (trp) fluorescence was observed in both glucation and fructation.

A size dependent folding contour for cytochrome C.

The paper describes an experimental construct of the folding route of the heme protein cytochrome-C. The construct highlights a slowing down near the nose of the folding funnel caused by the multiplicity of the energy traps near the native conformation created as a result of complex heme-peptide interaction. Interestingly the hydrodynamic size, the size heterogeneity and peroxidase activity serve as a triple measure of the distance of this near equilibrium departure from native conformation.