Isolation and functional characterization of a cyst(e)amine-sensitive protein protecting methyl-dithio groups.
We have previously shown that S-methylthio cysteine mixed disulfide and cystamine potently stimulate thiol production and glutathione synthesis of a human T-cell line in SH-poor medium. Here, we describe a simple photometric method for the determination of methylthio-mixed disulfides (MT-groups) and show that liver contains relatively large amount of MT-groups mainly associated with the globulin fractions. At least a part of methylthio (MT-) globulins is in a complex with a heat-stable protein protecting methylthio-groups against reduction and was designated as anti-methylthio factor (AMTF). Similar complexes are present in some animal sera. AMTF isolated from mouse liver was shown to specifically inhibit redox interaction of methyldithio-groups of various origin with thiols but loses this ability in the presence of some agents such as cyst(e)amine, 2-mercaptoethanol and dimethyl sulfoxide abrogating the MT-binding activity of AMTF (= cystamine-sensitive protein-CSP). AMTF purified by heat treatment and isopropanol fractionation was chromatographed on Superose-12 column. Preliminary results showed that the molecular mass of the active component is about 34 kDa consisting of two identical subunits. The possible biological role of MT-AMT complexes was discussed.
Jókay
István
I
National Center for Epidemiology, Microbiological Research Group, H-1529 Budapest, Hungary. ijokay@axelero.hu
Kelemenics
Katalin
K
Patthy
András
A
Bali
László
L
Bátkai
László
L
D000818:Animals; D003538:Cystamine / Q000494:pharmacology*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004220:Disulfides / Q000737:chemistry*; D008099:Liver / Q000737:chemistry; D008623:Mercaptoethanol / Q000494:pharmacology; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry*; D051379:Mice; D008970:Molecular Weight; D010783:Photometry / Q000379:methods; D011506:Proteins / Q000737:chemistry* / Q000302:isolation & purification*; D013438:Sulfhydryl Compounds / Q000378:metabolism*
D004220:Disulfides; D011506:Proteins; D013438:Sulfhydryl Compounds; C051224:methyl radical; D008623:Mercaptoethanol; D008697:Methane; D003538:Cystamine; D004121:Dimethyl Sulfoxide