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1978 (1)
1977 (1)
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1Author    ClemensVon Sonntag, Miral Dizdaroglu, Dietrich Schulte-FrohlindeRequires cookie*
 Title    y-Radiolysis of Cellobiose in N20-saturated Aqueous Solution Part II. Quantitative Measurements. Mechanisms of the Radical-induced Scission of the Glycosidic Linkage  
 Abstract    The y-radiolysis of cellobiose (10 -2 M) in N2O saturated aqueous solution has been investigated and the G-values of the following 21 products containing six or less C-atoms have been measured (G-values in parentheses): glucose (2.1), gluconic acid (0.70), 4-keto-glucose (0.07), 5-keto-glucose (0.05), 4-deoxy-glucose (0.27), 5-deoxy-gluconic acid (0.18), 2-deoxy-gluconic acid (0.13), 3-deoxy-4-keto-glucose (0.23), 2-deoxy-5-keto-glucose (0.34), 4-deoxy-5-keto-glucose (0.14), 6-deoxy-5-keto-glucose (0.02), arabinose (0.07), ribose (0.015), 2-deoxy-ribose (0.17), 3-deoxy-pentulose (0.01), erythrose (0.015), threose (0.015), 2-deoxy-tetrose (0.01), butanone-(2)-diol(1.4) (0.01), dihydroxyacetone (0.01), carbon monoxide (> 0.02). The formation of the major part (98%) of the measured products could be explained on the base of the following assumption: The first step of reaction sequence is abstraction of H atoms from C-H bonds of the cellobiose by OH radicals. Radicals at C-l', C-5' and C-4 and their successors undergo in a second step four types of reactions: hydrolysis, re-arrangement and H2O and CO elimination. In a third step the transformed radicals give rise to products by disproportionation reaction. Only two products out of 16 predicted under the above assumption are not observed. G-values for the attack at C-l', C-5' and C-4 are 1.4, 0.6 and 0.3 respectively. 
  Reference    (Z. Naturforsch. 31b, 857—864 [1976]; received February 25 1976) 
  Published    1976 
  Keywords    Carbohydrates, Radical Reactions, y-Radiolysis, Cellobiose, Glycosidic Linkage 
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 TEI-XML for    default:Reihe_B/31/ZNB-1976-31b-0857.pdf 
 Identifier    ZNB-1976-31b-0857 
 Volume    31 
2Author    Requires cookie*
 Title    Radiation Chemistry of Carbohydrates, XV OH Radical Induced Scission of the Glycosidic Bond in Disaccharides  
 Abstract    H e n r y k Z e g o t a * * a n d C l e m e n s v o n S o n n t a g In the y-radiolysis of deoxygenated, NaO-saturated aqueous solutions of maltose, lactose, gentiobiose, melibiose, trehalose and sucrose carbohydrate products containing five or six carbon atoms have been identified and their G-values measured. These products originate from the OH radical induced scission of the glycosidic bond of the disaccharides. The nature of the products is in agreement with a reaction scheme proposed previously for the radical induced scission of the glycosidic bond of cellobiose. It involves hydrolysis and the rearrangements of radicals with the free spin next to the glycosidic bond and to the lactol bridge. The nature the glycosidic bond (a, ß, 1-4, 1-6, 1-1, 1, 2) has only little influence on the G-values of its scission which range between about 1.9 and 3.5. 
  Reference    (Z. Naturforsch. 32b, 1060—1067 [1977]; received May 31 1977) 
  Published    1977 
  Keywords    y-Radiolysis, G-values, Mass Spectra, Radical Reactions 
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 TEI-XML for    default:Reihe_B/32/ZNB-1977-32b-1060.pdf 
 Identifier    ZNB-1977-32b-1060 
 Volume    32 
3Author    Requires cookie*
 Title    Radiation Chemistry o f Carbohydrates, VI* y-Radiolysis o f Glucose in Deoxygenated N20 Saturated Aqueous Solution  
 Abstract    M ir a l D i z d a r o g l u , D i e t e r H e n n e b e r g , G e r h a r d S c h o m b u r g , a n d Cl e m e n s v o n S o n n t a g In the y -radiolysis of deoxygenated N 20 -saturated aqueous solutions of D-glucose (10-2 M, 1 • 1019 — 4 • 1019 eV/g, dose rate 4.3 • 1018 eV/g • h at 25 °C), the following products have been identified: Gluconic acid (1), 2-deoxy-gluconic acid (2), arabinose (3), 2-deoxy-ribose (4), 5-deoxy-gluconic acid (5), glucosone (6), 3-deoxy-glucosone (7), 3-keto-glucose (8), [2-deoxy-3-keto-glucose (9), 4-deoxy-3-keto-glucose (10)]3, 4-keto-glucose (11), 3-deoxy-4-keto-glucose (12), 5-deoxy-4-keto-glucose (13), 5-keto-glucose (14), 2-deoxy-5-keto-glucose (15), 4-deoxy-5-keto-glucose (16), 6-deoxy-5-keto-glucose (17), glueo-hexodialdose (18), 5-deoxy-xylo-hexodialdose (19), ribose (20), xylose (21), erythrose (22), threose (23), 3-deoxy-pentulose (24), 2-butanone-(l,4)-diol (25), and dihydroxy-acetone (26). G-values were also determined. In the primary processes OH radicals and H atoms from the radiolysis of the solvent water abstract carbon bound hydrogen atoms from D-glucose to give all six possible primary glucosyl radicals. The observed products are formed in disproportionation reactions of the primary glucosyl radicals (1, 6, 8, 11, 14, 18) or of sugar radicals which originate from the primary glucosyl radicals by water elimination (2,, rearrangements (5, 14, 15), or loss of carbon monoxide (3, 4, 20). Products 1-5 and probably 20 have primary glucosyl radicals with the odd electron at C-l as precursors. Radicals with the free spin at C-2 give rise to the products 6 and 7. Attack at C-3 yield products 8-10, at C-4 products 11-13, at C-5 products 14-17, and an attack at C-6 products 18 and 19. Products 21-26 are formed in very low yields and hence are of minor importance. Their mechanism of formation has not been investigated. 
  Reference    (Z. Naturforsch. 30b, 416—425 [1975]; received January 28 1975) 
  Published    1975 
  Keywords    D-Glucose, y-Radiolysis, Glucosyl Radicals, Deoxy-sugars, Keto-glucoses 
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 TEI-XML for    default:Reihe_B/30/ZNB-1975-30b-0416.pdf 
 Identifier    ZNB-1975-30b-0416 
 Volume    30 
4Author    Requires cookie*
 Title    Radiation Chemistry of DNA-Model Compounds, VII* On the Formation of 5-Deoxy-D-erythro-pentos- 4-ulose and the Identification of Twelve Further Products from y-Irradiated Aqueous Solutions of Ribose-5-phosphate  
 Abstract    L o t h a k S t e l t e r , C l e m e n s v o n S o n n t a g , a n d D i e t r i c h S c h u l t e -F r o h l i n d e Different mechanisms are considered to explain the formation of 5-deoxy-D-erythro-pentos-4-ulose in the y-radiolysis of ribose-5-phosphate in aqueous solution. On the basis of deuterium labelling experiments one mech­ anism involving an enol as an intermediate could be excluded. The identification of twelve further radio-lysis products from ribose-5-phosphate is reported. 
  Reference    (Z. Naturforsch. 30b, 656—657 [1975]; received February 19 1975) 
  Published    1975 
  Keywords    y-Radiolysis, Ribose-5-phosphate, Carbohydrates, Radical Reactions, Radical Cations 
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 TEI-XML for    default:Reihe_B/30/ZNB-1975-30b-0656_n.pdf 
 Identifier    ZNB-1975-30b-0656_n 
 Volume    30 
5Author    BarryJ. Parsons, Dietrich Schulte-Frohlinde, Clemens Von SonntagRequires cookie*
 Title    Reaction of Br3' 2 -with 2-Deoxy-D-ribose. A Preferred Attack at C-l  
 Abstract    In the photolysis of 5-bromouracil containing DNA Br atoms are expected inter mediates. In order to evaluate the possible site of attack of the Br atom at the sugar moiety of DNA the reaction of 2-deoxy-D-ribose with the Br atom (complexed with two bromide ions) was investigated. Hydroxyl radicals generated by the radiolysis of N20 saturated aqueous solutions were converted into Br3 -2_ radicals by 1 M bromide ions. Br3-2-reacts with 2-deoxy-D-ribose (k = 3.7 • 10 4 M -1 s -1 , pulse radiolysis). The major product is 2-deoxy-D-erythro-pentonic acid (G = 2.4, y-radiolysis). It is formed by hydrogen abstraction from C-l and oxidation of this radical by other radicals. An alternative route via the radical at C-2 is neglible. It follows that Br3-2 ~ reacts preferentially at C-l of 2-deoxy-£>-ribose. 
  Reference    Z. Naturforsch. 33b, 666—668 (1978); received March 15 1978 
  Published    1978 
  Keywords    Pulse Radiolysis, y-Radiolysis, 2-Deoxy-D-ribose, G-values, Radical Reactions 
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 TEI-XML for    default:Reihe_B/33/ZNB-1978-33b-0666.pdf 
 Identifier    ZNB-1978-33b-0666 
 Volume    33