skip to main content

Title: Formation of 8-hydroxy(deoxy)guanosine and generation of strand breaks at guanine residues in DNA by singlet oxygen

Singlet molecular oxygen ({sup 1}O{sub 2}) was generated in aqueous solution (H{sub 2}O or D{sub 2}O) at 37 C by the thermal dissociation of the endoperoxide of 3,3'-(1,4-naphthylidene) dipropionate (NDPO{sub 2}). Guanosine and deoxyguanosine quench {sup 1}O{sub 2} with overall quenching rate constants of 6.2 {times} 10{sup 6} M{sup {minus}1} s{sup {minus}1} and 5.2 {times} 10{sup 6} M{sup {minus}1} s{sup {minus}1}, respectively. Reaction with {sup 1}O{sub 2} results in the formation of 8-hydroxyguanosine (8-OH-Guo) and 8-hydroxydeoxyguanosine (8-OH-dGuo), respectively, with a yield of 1.5% at 1 mM substrate with an NDPO{sub 2} concentration of 40 mM; a corresponding 8-hydroxy derivative is not formed from deoxyadenosine. in D{sub 2}O the yield of 8-OH-Guo is 1.5-fold that in H{sub 2}O. Sodium azide suppresses 8-OH-Guo and 8-OH-dGuo production. in contrast, the hydroxyl radical scavengers, tert-butanol, 2-propanol, or sodium formate, do not decrease the production of the 8-OH derivatives. The formation of 8-OH derivatives is significantly increased (2-5-fold) by thiols such as dithiothreitol, glutathione, cysteine, and cysteamine. With use of a plasmid containing a fragment of the mouse metallothionein 1 promoter (pMTP3') and a novel end-labeling technique, the position of {sup 1}O{sub 2}-induced single-strand breaks in DNA was examined. Strand breaks occur selectively at dGuo;more » no major differences (hot spots) were observed between individual guanines.« less
Authors:
; ; ;  [1] ;  [2]
  1. (Univ. Duesseldorf (West Germany))
  2. (Max-Planck-Inst. fuer Strahlenchemi, Muelheim (West Germany))
Publication Date:
OSTI Identifier:
5029122
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemistry; (United States); Journal Volume: 30:25
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; DNA; AUTORADIOGRAPHY; GUANINE; STRAND BREAKS; OXYGEN; BIOLOGICAL EFFECTS; AQUEOUS SOLUTIONS; HEAVY WATER; METALLOTHIONEIN; PEROXIDES; PLASMIDS; THIOLS; AMINES; AROMATICS; AZAARENES; CELL CONSTITUENTS; DISPERSIONS; ELEMENTS; HETEROCYCLIC COMPOUNDS; HYDROGEN COMPOUNDS; HYDROXY COMPOUNDS; METALLOPROTEINS; MIXTURES; NONMETALS; NUCLEIC ACIDS; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; ORGANIC SULFUR COMPOUNDS; OXYGEN COMPOUNDS; PROTEINS; PURINES; SOLUTIONS; WATER 550601* -- Medicine-- Unsealed Radionuclides in Diagnostics