title: Inhibition of the catalytic activity of rhodanese by S-nitrosylation using nitric oxide donors.
abstract: Rhodanese (EC 2.8.1.1.) from bovine liver contains four reduced cysteine groups. The -SH group of cysteine 247, located in a rhodanese active centre, transfers sulfane sulfur in a form of hydrosulfide (-S-SH) from appropriate donors to nucleophilic acceptors. We aimed to discover whether S-nitrosylation of critical cysteine groups in rhodanese can inhibit activity of the enzyme by covalent modification of -SH groups. The inhibition of rhodanese activity was studied with the use of a number of nitric oxide (NO) donors. We have successfully confirmed using several methods that the inhibition of rhodanese activity is a result of the formation of stable S-nitrosorhodanese. Low molecular weight NO donors, such as S-nitroso-N-acetylpenicillamine (SNAP) and S-nitrosoglutathione (GSNO), inactivate rhodanese and are much more effective in this regard (100% inhibition at 2.5mM) than such known inhibitors of this enzyme, as N-ethylmaleimide (NEM) (25 mM < 50%) or sulfates(IV) (90% inhibition at 5mM). On the other hand, sodium nitroprusside (SNP) and nitrites inhibit rhodanese activity only in the presence of thiols, which suggests that S-nitrosothiols (RSNO) also have to participate in this reaction in this case. A demonstration that rhodanese activity can be inhibited as a result of S-nitrosylation suggests the possible mechanism by which nitric oxide may regulate sulfane sulfur transport to different acceptors.
authors.affiliation: Institute of Medical Biochemistry Collegium Medicum, Jagiellonian University, 31-034 Kraków, Poland.
authors.forename: Inga
authors.initials: I
authors.lastname: Kwiecień
authors.forename: Maria
authors.initials: M
authors.lastname: Sokołowska
authors.forename: Ewa
authors.initials: E
authors.lastname: Luchter-Wasylewska
authors.forename: Lidia
authors.initials: L
authors.lastname: Włodek
mesh_terms: D000818:Animals; D002417:Cattle; D003545:Cysteine / Q000378:metabolism*; D004220:Disulfides / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000378:metabolism; D008099:Liver / Q000201:enzymology; D015394:Molecular Structure; D009569:Nitric Oxide / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000737:chemistry / Q000378:metabolism*; D005996:Nitroglycerin / Q000378:metabolism; D009599:Nitroprusside / Q000378:metabolism; D011190:Potassium Cyanide / Q000378:metabolism; D026423:S-Nitroso-N-Acetylpenicillamine / Q000378:metabolism; D026422:S-Nitrosoglutathione / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism; D013884:Thiosulfate Sulfurtransferase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism*
chemical_list: D004220:Disulfides; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D013438:Sulfhydryl Compounds; D009599:Nitroprusside; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; D013455:Sulfur; D026423:S-Nitroso-N-Acetylpenicillamine; D013884:Thiosulfate Sulfurtransferase; D005996:Nitroglycerin; D003545:Cysteine; D011190:Potassium Cyanide