2.4.4. Quantification of protein carbonyls
A serum sample (5 ll) was denatured by 5 ll 12% (w/v) sodium dodecyl sulfate
(SDS). Protein carbonyls present in samples were converted to 2,4 dinitrophenylhydrazine
(DNP) hydrazone by DNP in 2 M HCl for 20 min at room temperature. Samples
were diluted in coating buffer, adsorbed to wells of an ELISA plate and blocked
with PBS/0.1% tween/1% bovine serum albumin, then probed with an anti-DNP antibody
(Sigma D9656) and a horseradish peroxidase (HRP) conjugated secondary
antibody (ECL anti-rabbit IgG, HRP-linked whole antiobody from donkey) for 3 h
and 1 h respectively at room temperature. A tetramethylbenzidine (TMB) substrate
was then added and allowed to oxidize for 15 min to a sapphire-blue complex at
room temperature. The reaction was stopped by addition of 2 M HCl and OD measured
at 450 nm.