Chemical characterization of isocyahate-protein conjugates.
Toxicol Appl Pharmacol 1979 Oct; 51(1):39-46
The rates of reaction of toluene-diisocyanate (26471625) (TDI) and hexamethylene-diisocyanate (822060) (HDI) with human serum albumin (HSA) were studied. Reactions of HDI and TDI with HSA were carried out at room temperature. An 0.9 gram (g) of HSA in solution was reacted with 2.1g or 0.21g HDI or 2.4g TDI. Aliquots were taken at selected time intervals after the start of the reaction. Ammonium- carbonate was used to stop the reactions, and portions of the isocyanate protein conjugates were purified by centrifugation, dialysis, and precipitation. Assays were performed for the quantity of isocyanate bound to protein, protein content, amino acid residues, and free amino groups. Protein derivatives from the reaction of TDI with HSA consisted of 78 percent bisureido and 22 percent monoureido forms. TDI bound protein reached a maximum at 20 minutes. The number of recovered lysine residues was the same in unconjugated HSA as in TDI HSA conjugates. In both high and low concentrations of HDI, the amount of isocyanate bound to protein as the amine hexamethylenediamine increased with time. The only significant change in amino acid residues recovered from HSA before and after reaction with HDI occurred in the lysyl residues. At 0 minutes, 47.36 nanomoles (nmol) were recovered; after 180 minutes, 22.60nmol were recovered. The authors conclude that reaction time is the most important factor in protein conjugation with aromatic and aliphatic hydrocarbons.
NIOSH-Publication; NIOSH-Grant; Isocyanates; Chemical-composition; Biochemical-analysis; Protein-biosynthesis; Reaction-rates; Molecular-biology; Amino-acids; Aliphatic-compounds; Aromatic-hydrocarbons
Internal Medicine University of Cincinnati 231 Bethesda Avenue Cincinnati, Ohio 45267
Toxicology and Applied Pharmacology
University of Cincinnati, Cincinnati, Ohio