Detection of de novo β-glucosidase (EC 3.2.1.21) Enzyme Activity in Tomato (Solanum lycopersicum L.) in 4-methylumbelliferyl ß-D-glucoside Zymograms

This study was conducted to detect β-glucosidase (EC 3.2.1.21) enzymes in tomato (Solanum lycopersicum L.). While no previous reports are available to describe β-glucosidases in tomato, maize (Zea mays L.) was used as a reference. Total plant proteins were isolated from different tomato organs (young seedlings, young leaves, old leaves, roots, green immature fruits, red mature fruits) and from maize etiolated seedlings. Furthermore, maize recombinant β-glucosidase 1 (rGlu1) was used. Soluble protein fractions were subjected to subsequent 35% and 65% ammonium sulfate precipitation. To detect potential enzymatic activities, gels (native and denaturing) were incubated with 4-methylumbelliferyl ß-D-glucoside (4-MUGlc). Only tomato young leaf zymogram showed positive 4-MUGlc hydrolysis as compared to maize native and rGlu1. The herein described results suggest, for the first time, the presence of at least one β-glucosidase in tomato. Although no signs of 4-MUGlc hydrolysis could be resolved for other tomato tissues, further β-glucosidases are presumably present, however, they may utilize different untested substrates