Lowry Protein Assay. The Lowry procedure is one of the most venerable and widely-used protein assays, being first described in 1951 [Lowry et al., J. Biol. Chem. 193: 265-275 (1951)]. Under alkaline conditions, copper complexes with protein. When folin phenol reagent (phospho-molybdic-phosphotungstic reagent) is added, the Folin-phenol reagent binds to the protein. Bound reagent is slowly reduced and changes color from yellow to blue. P.J. Hansen, Dept. of Animal Sciences, University of Florida. - [Read Lowry Protein Assay]