MODIFICATION OF THE LOWRY METHOD FOR ANALYSIS OF SOLUBLE LATEX PROTEINS

• Published in: Toxicology mechanisms and methods 2000, Vol.10 (3), p.165-179
• Main Authors: Lucas, Anne D., Tomazic-Jezic, Vesna J.
• Format: Article
• Language: English
• Subjects: Allergens; Lowry Method; Natural Rubber Latex Proteins Protein; Quantitation
• ISSN: 1537-6516; 1051-7235; 1537-6524
• DOI: 10.1080/10517230050121589

Proteins from natura lrubber latex (NRL) can cause local and systemic reactions in people who are allergic to it. Reducing the total protein in NRL products to minimize the allergenic potential requires methods of accurately estimating the amount of protein. Previous work in this laboratory and others has indicated that, of the colorimetric assays, a modified Lowry method performs best. The American Society for Testing Materials (ASTM) has adopted the modified Lowry method for analysis of soluble NRL proteins.This method, although the best currently available, lacks sufficient reproducibility and sensitivity. In anattempt to improve the method, we address in this article the importance of various extraction conditions and additional approaches to eliminate interfering substances that may cause the false-positive values in the test. Depending on the chemical composition of the accelerants added during manufacturing processes, different means may be employed to remove or to account for the presence of these small organic molecules. The best general way to remove these chemical compounds is the partitioning of the latex extracts with ethyl acetate followed by acid precipitation. Although there is no one perfect method for all NRL proteins and products, the data presented here indicate that changes in the standard protocol of the Lowry method may result in more reproducible and reliable results.