Effect of some chemicals on the accuracy of protein estimation by the Lowry method

Abstract

The influence of 57 chemicals (mineral and organic acids, organic solvents, phenolic compounds, mineral and organic salts) on the efficiency of protein determination by the Lowry method was assessed. The study revealed the Lowry method to be unreliable in an acidic and increasing vitamin C-rich medium. For organic solvents, it is advisable to evaporate these compounds when they are used to extract proteins, prior to proteins measurement the Lowry method. The influence of phenolic compounds on the Lowry method was found to be governed by the structure of their molecules (presence of double bounds, number of OH groups, presence of methyl groups, etc.), while ammonium sulfate, which is a major agent used in the enzyme purification process, was found to result in an overestimation of the protein content. Therefore, its use for enzyme purification should be done with caution.

Keywords: Lowry method, protein determination, method validation, chemical interference

Biokemistri Vol. 17(2) 2005: 73-81