Abstract
The effect of gossypol on the enzymatic activity of crystalline trypsin, pepsin, muscle aldolase, and the activation of pepsinogen has been established in in vitro systems. Trypsin activity was completely inhibited using p-toluene-sulfonyl-L-arginine methyl ester as substrate, after trypsin was incubated 2 hr with 5 x 10⁻⁴ gossypol (15:1 molar ratio gossypol/trypsin) in 0.04 M borate buffer containing 5% methyl Cellosolve pH 8.1 at 25°. Pepsin activity was not inhibited after prolonged incubation with 4 to 12 molar equivalents of gossypol. On the other hand, the activation of pepsinogen was completely prevented after 2 hr incubation with 1.5 x 10⁻⁴ M gossypol (3:1 molar ratio gossypol/pepsinogen) in 0.1 sodium buffer containing 10% ethanol, pH8.0 at 35°. The potential activity of pepsinogen was assayed using hemoglobin as the substrate. Optimum condition for the reaction between gossypol and the zymogen were found to be pH 8.0, 10% ethanol and 35°. Attempts were made to locate the pepsinogen residue(s) involved in the bonding with gossypol by digesting pepsinogen-gossypol and pepsinogen preparations with trypsin and papain and separating the resulting peptides by high-voltage paper electrophoresis. Amino acid composition of selected peptides indicated that lysine was bonding to gossypol. A tentative scheme for the reaction between gossypol and pepsinogen was postulated based on kinetic experiments and the number of peptides resulting from tryptic digestion. ...
Tanksley, Thomas Dewitt (1968). Effect of gossypol on specific enzyme systems. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -172922.