TY - JOUR
T1 - Substrate specificity and ionization potential in chloroperoxidase- catalyzed oxidation of diesel fuel
AU - Ayala, Marcela
AU - Robledo, Norma R.
AU - Lopez-Munguia, Agustin
AU - Vazquez-Duhalt, Rafael
PY - 2000/7/1
Y1 - 2000/7/1
N2 - Straight-run diesel fuel containing 1.6% of sulfur was enzymatically oxidized with chloroperoxidase from Caldariomyces rumago. Most organosulfides and thiophenes were transformed to form sulfoxides and sulfones. The oxidized organosulfur compounds can be effectively removed by distillation. The resulting fraction after distillation contained only 0.27% sulfur, while the untreated straight-run diesel fuel after the same distillation process still showed 1.27% sulfur. To know the chemical nature of the products, nine organosulfur compounds and 12 polycyclic aromatic compounds (PACs) were transformed by chloroperoxidase in the presence of chloride and hydrogen peroxide. Organosulfur compounds were only oxidized to form sulfoxides and sulfones, and no chlorinated derivatives were detected, except for bithiophene. In contrast, PACs were exclusively chlorinated, and no oxidized derivatives could be found. No enzymatic activity was detected on PACs with an ionization potential higher than 8.52 eV, while in the lower region it was found that the higher the ionization potential of the PAC the lower the specific activity. On the other hand, the substrate ionization potential did not seem to influence chloroperoxidase activity in the oxidation of organosulfur compounds. All organosulfur compounds tested were oxidized by chloroperoxidase. From double-substrate experiments, it appears that organosulfur compounds are oxidized by both compound I and compound X enzyme intermediates, while PACs react only with the halogenating intermediate, compound X.
AB - Straight-run diesel fuel containing 1.6% of sulfur was enzymatically oxidized with chloroperoxidase from Caldariomyces rumago. Most organosulfides and thiophenes were transformed to form sulfoxides and sulfones. The oxidized organosulfur compounds can be effectively removed by distillation. The resulting fraction after distillation contained only 0.27% sulfur, while the untreated straight-run diesel fuel after the same distillation process still showed 1.27% sulfur. To know the chemical nature of the products, nine organosulfur compounds and 12 polycyclic aromatic compounds (PACs) were transformed by chloroperoxidase in the presence of chloride and hydrogen peroxide. Organosulfur compounds were only oxidized to form sulfoxides and sulfones, and no chlorinated derivatives were detected, except for bithiophene. In contrast, PACs were exclusively chlorinated, and no oxidized derivatives could be found. No enzymatic activity was detected on PACs with an ionization potential higher than 8.52 eV, while in the lower region it was found that the higher the ionization potential of the PAC the lower the specific activity. On the other hand, the substrate ionization potential did not seem to influence chloroperoxidase activity in the oxidation of organosulfur compounds. All organosulfur compounds tested were oxidized by chloroperoxidase. From double-substrate experiments, it appears that organosulfur compounds are oxidized by both compound I and compound X enzyme intermediates, while PACs react only with the halogenating intermediate, compound X.
UR - http://www.scopus.com/inward/record.url?scp=0034235755&partnerID=8YFLogxK
U2 - 10.1021/es991270o
DO - 10.1021/es991270o
M3 - Artículo
SN - 0013-936X
VL - 34
SP - 2804
EP - 2809
JO - Environmental Science and Technology
JF - Environmental Science and Technology
IS - 13
ER -