Protein measurement in forest litter

A method to extract proteins and measure their concentrations in forest litter was developed using evergreen oak litter as a model system. We considered factors that affect the extraction of proteins and the measurement of their concentrations. The factors studied included powdering of the leaves, nature and molarity of the extraction solvent, amount of powdered leaves used for protein extraction, concentration of the extracts, adding polyvinylpolypyrrolidone (PVPP) and Tween 80 during the extraction, extraction time, incubation time with the colorimetric reagent and colorimetric method used. Results showed in particular that CaCl2 was the only extraction solvent which allowed one to obtain extracts without interfering substances for the measurement of protein concentrations. Adding PVPP and Tween 80 during the extraction procedure led to an increase in the protein concentrations in extracts by eliminating precipitating substances such as tannins. The modalities of the other parameters were also optimised and are discussed for more accurate protein measurement.