Inactivation of cysteine and serine proteases by singlet oxygen.
The reaction of singlet oxygen with individual proteins is less well understood than that with other biological molecules. The inhibition of caspase 3 by singlet oxygen appears to involve the modification of a catalytic cysteine residue, since the reactivity of the sulfhydryl with alkylating agents decreased after singlet oxygen treatment. In addition to three cysteine proteases, two serine proteases were also found to be inhibited by singlet oxygen with a similar dose dependency, while an aspartate protease and a metalloprotease were not affected. The carbonyl content of these enzymes was elevated as the result of treatment with singlet oxygen. The catalytic center in serine proteases and cysteine proteases, in which catalytic reactions are based on similar mechanisms involving nucleophilic catalysis assisted by histidine as a general acid/base, can be expected to be modified by singlet oxygen and undergo inactivation.
Suto
Daisuke
D
Department of Biomolecular Function, Graduate School of Medical Science, Yamagata University, 2-2-2 Iidanishi, Yamagata City, Yamagata 990-9585, Japan.
Iuchi
Yoshihito
Y
Ikeda
Yoshitaka
Y
Sato
Kazuaki
K
Ohba
Yoshihiro
Y
Fujii
Junichi
J
D000818:Animals; D061945:Caspase Inhibitors; D002417:Cattle; D015853:Cysteine Proteinase Inhibitors / Q000737:chemistry / Q000502:physiology*; D006801:Humans; D015842:Serine Proteinase Inhibitors / Q000737:chemistry / Q000502:physiology*; D026082:Singlet Oxygen / Q000737:chemistry* / Q000502:physiology*
D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D015842:Serine Proteinase Inhibitors; D026082:Singlet Oxygen