Wheat Bran Globulins: Competitive Inhibitors of Mushroom Tyrosinase

The inhibitory capacity of the globulin fraction of wheat bran against the diphenolase activity of mushroom tyrosinase, using L-tyrosine as substrate, was evaluated. Enzyme kinetics was monitored in the presence of globulin solutions by measuring the absorbance at 475nm. Lineweaver-Burk plots were drawn in order to determine $V_{max}$, $K_m$, and type of inhibition. Results showed that globulins from wheat bran competitively inhibited, the activity of mushroom tyrosinase with a $K_I$ of 0.79%(w/v). The degree of inhibition was 24% at 2 mM of the substrate L-tyrosine.