QUANTITATION OF NATURAL RUBBER LATEX PROTEINS: EVALUATION OF VARIOUS PROTEIN MEASUREMENT METHODS

Abstract

The allergy to natural rubber latex (NRL) proteins is a significant occupational health hazard. The elimination or reduction of the water-soluble proteins from finished NRL products is oneapproach aimed at decreasing further sensitization and reactions to these allergens. To achieve this goal, a reliable protein measurement method is required. Several published and widely used methods for protein measurement in finished NRL products demonstrate major inconsistencies in the quantification of extractable NRL proteins in comparison to the Kjeldahl nitrogen assay and the gravimetrically determined reference. Multiple protein assays and several reference proteins were examined to determine the most suitable method for the quantitation of soluble NRL proteins. Among the reference proteins evaluated (BSA, BGG, and OA), OA was found to correlate best with gravimetrically determined levels of NRL proteins. Of the protein assays evaluated (Bradford, BCA, and Lowry), the modified Lowry assay demonstrated the best uniformity and a good correlation with the Kjeldahl nitrogen assay. The commercial Lowry assay kit, Bio-Rad DC Protein Assay, was comparable to the laboratory-prepared reagents, and both demonstrated good sensitivity and precision. Altering a sample to reagent ratio increased the sensitivity of the test.

Keywords: :

• Allergy;Natural Rubber Latex;Protein Quantitation