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1Author    Hermann Esterbauer, Helmward Zöllner, N. Orbert ScholzRequires cookie*
 Title    Reaction of Glutathione with Conjugated Carbonyls  
 Abstract    1. GSH reacts with conjugated carbonyls according to the equation: G S H + R —C H = C H — COR R —CH(SG) —CH2—COR. The forward reaction follows second order, the reverse reaction first order kinetics. It is assumed that this reaction reflects best the ability of conjugated carbonyls to inactivate SH groups in biological systems. 2. The rate of forward reaction increases with pH approx. parallel with asH • Besides OH" ions also proton donors (e. g. buffers) increase the rate. The catalytic effect of pH and buffer is inter­ preted in view of the reaction mechanism. 3. The equilibrium constants as well as the rate constants for forward (k t) and reverse reaction show an extreme variation depending on the carbonyl structure. Acrolein and methyl vinyl ketone (k t = 120 and 32 mol-1 sec-1 , resp.) react more rapidly than any other carbonyl to give very stable adducts (half-lives for reverse reaction 4.6 and 60.7 days, resp.). Somewhat less reactive are 4-hydroxy-2-alkenals and 4-ketopentenoic acid (k t between 1 and 3 mol-1 sec-1), but they also form very stable adducts showing half-lives between 3.4 and 19 days. All other carbonyl studied react either very slowly (e. g. citral, ethly crotonate, mesityl oxide, acrylic acid) or form very labile adducts (crotonal, pentenal, hexenal, 3-methyl-butenone). Comparing biological activities of con­ jugated carbonyls their reactivity towards HS (/cj) and the stability of the adducts must be con­ sidered. 
  Reference    (Z. Naturforsch. 30c, 466—473 [1975]; received January 17/April 11975) 
  Published    1975 
  Keywords    Glutathione, Conjugated Carbonyls, Rate Constant, Equilibrium Constant 
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 TEI-XML for    default:Reihe_C/30/ZNC-1975-30c-0466.pdf 
 Identifier    ZNC-1975-30c-0466 
 Volume    30 
2Author    Heinz Rennenberg, Reinhard Steinkamp, Andrea PolleRequires cookie*
 Title    Evidence for the Participation of a 5-Oxo-prolinase in Degradation of Glutathione in Nicotiana tabacum  
 Abstract    During degradation o f glutathione in tobacco suspension cultures substancial amounts o f 5-oxo-proline are formed in vivo as well as in crude cell homogenates in vitro. The existance o f a 5-oxo-prolinase that catalyzes the conversion of 5-oxo-proline to glutamic acid was demonstrated in tobacco cells, grown with glutathione as sole sulfur source. 
  Reference    Z. Naturforsch. 35c, 708—711 (1980); received June 18 1980 
  Published    1980 
  Keywords    5-Oxo-prolinase, Glutathione, Tobacco, Tissue Culture 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0708.pdf 
 Identifier    ZNC-1980-35c-0708 
 Volume    35 
3Author    EvaBenedikt Lüönd, Hans-Peter Köst, Wolfhart RüdigerRequires cookie*
 Title    Isolation and Synthesis of New Bile Pigments Possibly Related to the Biosynthesis of the Phycocyanin Chromophore  
 Abstract    After incubation with 5-aminolevulinic acid and cysteine or 5-amino-levulinic acid and glutathione, Cyanidium caldarium excreted two new bile pigments 1 and 2. Their structures are identified by spectroscopical methods. By chemical addition of cysteine, glutathione and hy­ drogen sulfide to the ethyliden double bond of ZT-phycocyanobilin, the bile pigments 3-6 were obtained. 
  Reference    Z. Naturforsch. 45c, 1099—1110 (1990); received September 12 1990 
  Published    1990 
  Keywords    Cyanidium caldarium, Phycocyanobilin, Thiol Adducts, Cysteine, Glutathione 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-1099.pdf 
 Identifier    ZNC-1990-45c-1099 
 Volume    45 
4Author    A. Kira, W. Adano3, MitsuharuA. Zeta3, Shin-Ichi Itotani3, Ai Kanda3, Toshio Iwaki3, Tom Oaki Tairab, YasushiF. Ujiib, Yoshifumi Nishiurac, HaruhikoM. Urasec, Nobuo HonamRequires cookie*
 Title    Change of Ascorbic Acid Level after Grafting of Tomato Seedlings  
 Abstract    Grafting is an easy way to produce a new seedling, which can tolerate against various stresses. During the acclimation after grafting, however, the seedlings still suffer a severe water stress. It is well known that water stress produces active oxygen to oxidize ascorbic acid. The concentration of ascorbic acid in the leaves was analyzed by HPLC equipped with an electrochemical detector. The column used was SP-120-5-O D S-BP (DAISO, JAPAN) and elution was performed with 0.1 m phosphate buffer, pH 3.0. After grafting the seedlings were acclimated under a 6-hr light/dark regimen. The content of ascorbic acid increased gradually during 2 days compared with control. The ascorbate peroxidase showed about constant activity, so the increase of ascorbic acid may be due to its requirement to cure the grafting. 
  Reference    Z. Naturforsch. 54c, 830—8 (1999); receivced December 20 1998/February 3 1999 
  Published    1999 
  Keywords    Ascorbate Peroxidase, Ascorbic Acid, Glutathione, Grafting, Water Stress 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0830.pdf 
 Identifier    ZNC-1999-54c-0830 
 Volume    54 
5Author    Helmut Sapper, Sa-Ouk Kang, H Ans-H Elm, Ut Paul, W. Olfgang, Lohm AnnRequires cookie*
 Title    The Reversibility of the Vitamin C Redox System: Electrochemical Reasons and Biological Aspects  
 Abstract    The biological efficacy o f vitamin C depends on its redox abilities as given by the relations between ascorbic acid, semidehydroascorbic acid, and dehydroascorbic acid. It is shown by means of proton magnetic resonance spectroscopy that the enzymatic (by ascorbate oxidase) as well as non-enzymatic (by iodine) oxidation o f ascorbic acid is, in principle, reversible despite the hydration and structural changes during the formation o f dehydroascorbic acid. The strong redox activity o f semidehydroascorbic acid which results in a fast disproportionation to ascorbic acid and dehydroascorbic acid is inferred from an inversion o f the electrochemical potentials o f the vitamin C redox system. The capacity o f this is maintained by a fast reduction o f dehydro­ ascorbic acid e.g. by reduced glutathione, preventing its delactonization and further degradation. 
  Reference    Z. Naturforsch. 37c, 942 (1982); received May 19/July 20 1982 
  Published    1982 
  Keywords    Vitamin C, Dehydroascorbic Acid, Glutathione, Ascorbate Oxidase, NM R Spectroscopy 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0942.pdf 
 Identifier    ZNC-1982-37c-0942 
 Volume    37 
6Author    C.K C Ottingham, K. K. HatziosRequires cookie*
 Title    Influence of the Safener Benoxacor on the Metabolism of Metolachlor in Corn  
 Abstract    The herbicide safener benoxacor (CGA -154281) is effective in protecting corn from meto­ lachlor injury. Glutathione-S-transferase (GST) activity of corn seedlings was stimulated by low concentrations of benoxacor as was the formation of a polar metabolite identified as the glutathione (GSH) conjugate of metolachlor. A similar degree of enhancement of metolachlor metabolism was observed in both a metolachlor-tolerant ('Cargill 7567') and a metolachlor-susceptible ('Northrup-King 9283') corn line. The total GSH content o f shoots o f the meto-lachlor-susceptible corn hybrid was not affected by benoxacor treatment, but an increase was noted for shoots of the tolerant corn hybrid. The two corn hybrids with differential tolerance to metolachlor also differ in their dose response to benoxacor with higher safener concentra­ tions failing to induce or inhibit GST activity of the tolerant 'Cargill 7567' corn line. Stimula­ tion of GST activity and a corresponding enhanced rate of metolachlor metabolism can ac­ count for the safening effect of benoxacor. These mechanism of action of dichloroacetamide safeners. 
  Reference    Z. Naturforsch. 46c, 846—849 (1991); received March 26 1991 
  Published    1991 
  Keywords    Metolachlor, Glutathione-S-transferase, Glutathione, Benoxacor, Corn, Zeam ays L 
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 TEI-XML for    default:Reihe_C/46/ZNC-1991-46c-0846.pdf 
 Identifier    ZNC-1991-46c-0846 
 Volume    46 
7Author    JohnV. Dean, JohnW. Gronw, MichaelP. AndersonRequires cookie*
 Title    Glutathione S-Transferase Activity in Nontreated and CGA-154281- Treated Maize Shoots  
 Abstract    Fast protein liquid chromatography (anion exchange) was used to separate glutathione S-transferase isozymes in nontreated etiolated maize shoots and those treated with the herbi­ cide safener C G A -154281 4-(dichloroacetyl)-3,4-dihydro-3-methyl-2 H-l ,4-benzoxazine. Non­ treated shoots contained isozymes active with the following substrates: fra/?s-cinnamic acid (1 isozyme), atrazine (3 isozymes), l-chloro-2,4-dinitrobenzene (1 isozyme), metolachlor (2 isozymes) and the sulfoxide derivative of S-ethyl dipropylcarbamothioate (2 isozymes). Pre­ treatment of shoots with the safener C G A -154281 (1 (aM) had no effect on the activity of the isozymes selective for rratts-cinnamic acid and atrazine but increased the activity of the consti-tutively-expressed isozymes that exhibit activity with l-chloro-2,4-dinitrobenzene, metola­ chlor and the sulfoxide derivative of S-ethyl dipropylcarbamothioate. The safener pretreat­ ment also caused the appearance o f one new isozyme active with l-chloro-2,4-dinitrobenzene and one new isozyme active with metolachlor. The results illustrate the complexity of gluta­ thione S-transferase activity in etiolated maize shoots, and the selective enhancement of gluta­ thione S-transferase isozymes by the safener CG A -154281. 
  Reference    Z. Naturforsch. 46c, 850—855 (1991); received March 26 1991 
  Published    1991 
  Keywords    CG A-154281, Safener, Glutathione S-Transferase, Glutathione, Maize 
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 TEI-XML for    default:Reihe_C/46/ZNC-1991-46c-0850.pdf 
 Identifier    ZNC-1991-46c-0850 
 Volume    46