Gold nanoparticle sensor for homocysteine thiolactone-induced protein modification.
Homocysteine thiolactone-induced protein modification (HTPM) is a unique post-translational protein modification that is recognized as an emergent biomarker for cardiovascular disease. HTPM involves the site-specific acylation of proteins at lysine residues by homocysteine thiolactone (HTL) to produce protein homocystamide, which has been found at elevated levels in patients with coronary heart disease. Herein, we report the development of a novel gold nanoparticle (GNP) biochemical sensor for detection of protein homocystamide in an in vitro serum protein-based model system. Human serum albumin (HSA) and human sera were subjected to HTPM in vitro to produce HSA-homocystamide or serum protein homocystamide, respectively, which was subsequently treated with citrate-capped GNPs. This GNP sensor typically provided instantaneous visual confirmation of HTPM in the protein model systems. Transmission electron microscopy images of the GNPs in the presence of HSA-homocystamide suggest that modification-directed nanoparticle assembly is the mechanism by which the biochemical sensor produces a colorimetric signal. The resultant nanoparticle-protein assembly exhibited excellent thermal and dilutional stability, which is expected for a system stabilized by chemisorption and intermolecular disulfide bonding. The sensor typically provided a linear response for modified human sera concentrations greater than approximately 5 mg/mL. The calculated limit of detection and calibration sensitivity for the method in human sera were 5.2 mg/mL and 13.6 AU . (microg/mL)-1, respectively.
Gates
Arther T
AT
Department of Chemistry and Department of Biological Engineering, Louisiana State University, Baton Rouge, LA 70803, USA.
Fakayode
Sayo O
SO
Lowry
Mark
M
Ganea
Gabriela M
GM
Murugeshu
Abitha
A
Robinson
James W
JW
Strongin
Robert M
RM
Warner
Isiah M
IM
D006046:Gold / Q000737:chemistry*; D006710:Homocysteine / Q000031:analogs & derivatives* / Q000737:chemistry; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D012709:Serum Albumin / Q000737:chemistry* / Q000648:ultrastructure; D013053:Spectrophotometry; D013696:Temperature
D012709:Serum Albumin; D006710:Homocysteine; D006046:Gold; C007957:homocysteine thiolactone