Partial purification and characterization of two proteases fromAgave fourcroydes

Large amounts of wastes are produced by the henequen industry from which it may be possible to obtain products of commercial importance. Our laboratory has detected proteolytic activity inAgave fourcroydes (henequen) juice. The proteolytic activity is a result of two proteases of 14,500 and 12,000 daltons, respectively. Both enzymes are very stable at -20°C., when freeze-dried and in the presence of EDTA and cysteine. They differ in pH optimum and thermal stability.     

Catalytic oxidation of para-substituted phenols with cobalt–Schiff base complexes/O2—selective conversion of syringyl and guaiacyl lignin models to benzoquinones

Models of guaiacyl (G) and syringyl (S) subunits in lignin have been catalytically oxidized to their corresponding p-quinones in the presence of molecular oxygen. The oxidation of syringyl-like phenols readily occurred with 5-coordinate cobalt catalysts on which one of the ligands is a monodentate pyridine or imidazole base that coordinates axially to the metal. Formation of p-quinones with this system depends on the coordination of the axial base to the metal as influenced by its pK_a and its size. The yield of p-quinones from guaiacyl models was markedly improved by the addition of a sterically hindered aliphatic nitrogen base that does not coordinate to the catalyst. A mechanism involving deprotonation of the phenol substrate by the bulky base is proposed.