title: S-Nitrosoglutathione is a substrate for rat alcohol dehydrogenase class III isoenzyme.
abstract: An enzyme isolated from rat liver cytosol (native molecular mass 78. 3 kDa; polypeptide molecular mass 42.5 kDa) is capable of catalysing the NADH/NADPH-dependent degradation of S-nitrosoglutathione (GSNO). The activity utilizes 1 mol of coenzyme per mol of GSNO processed. The isolated enzyme has, as well, several characteristics that are unique to alcohol dehydrogenase (ADH) class III isoenzyme: it is capable of catalysing the NAD+-dependent oxidations of octanol (insensitive to inhibition by 4-methylpyrazole), methylcrotyl alcohol (stimulated by added pentanoate) and 12-hydroxydodecanoic acid, and also the NADH/NADPH-dependent reduction of octanal. Methanol and ethanol oxidation activity is minimal. The enzyme has formaldehyde dehydrogenase activity in that it is capable of catalysing the NAD+/NADP+-dependent oxidation of S-hydroxymethylglutathione. Treatment with the arginine-specific reagent phenylglyoxal prevents the pentanoate stimulation of methylcrotyl alcohol oxidation and markedly diminishes the enzymic activity towards octanol, 12-hydroxydodecanoic acid and S-hydroxymethylglutathione; the capacity to catalyse GSNO degradation is also checked. Additionally, limited peptide sequencing indicates 100% correspondence with known ADH class III isoenzyme sequences. Kinetic studies demonstrate that GSNO is an exceptionally active substrate for this enzyme. S-Nitroso-N-acetylpenicillamine and S-nitrosated human serum albumin are not substrates; the activity towards S-nitrosated glutathione mono- and di-ethyl esters is minimal. Product analysis suggests that glutathione sulphinamide is the major stable product of enzymic GSNO processing, with minor yields of GSSG and NH3; GSH, hydroxylamine, nitrite, nitrate and nitric oxide accumulations are minimal. Inclusion of GSH in the reaction mix decreases the yield of the supposed glutathione sulphinamide in favor of GSSG and hydroxylamine.
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA. djensen@hendrix.jci.tju.edu
authors.forename: D E
authors.initials: DE
authors.lastname: Jensen
authors.forename: G K
authors.initials: GK
authors.lastname: Belka
authors.forename: G C
authors.initials: GC
authors.lastname: Du Bois
mesh_terms: D000426:Alcohol Dehydrogenase / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D003600:Cytosol / Q000201:enzymology; D005978:Glutathione / Q000031:analogs & derivatives* / Q000378:metabolism; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D007850:Lauric Acids / Q000378:metabolism; D008099:Liver / Q000201:enzymology*; D008969:Molecular Sequence Data; D009243:NAD / Q000494:pharmacology; D009603:Nitroso Compounds / Q000378:metabolism*; D000442:Octanols / Q000378:metabolism; D051381:Rats; D026422:S-Nitrosoglutathione; D013379:Substrate Specificity
chemical_list: D007527:Isoenzymes; D007850:Lauric Acids; D009603:Nitroso Compounds; D000442:Octanols; D009243:NAD; C031263:12-hydroxydodecanoic acid; D026422:S-Nitrosoglutathione; D000426:Alcohol Dehydrogenase; D005978:Glutathione