Neocarzinostatin-induced hydrogen atom abstraction from C-4 prime and C-5 prime of the T residue at a d(GT) step in oligonucleotides: Shuttling between deoxyribose attack sites based on isotope selection effects

Journal Article · Tue Feb 26 00:00:00 EST 1991 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00222a005· OSTI ID:5715443

Kappen, L S; Goldberg, I H ^[1]; Frank, B L; Worth, L Jr; Christner, D F; Kozarich, J W ^[2]; Stubbe, J ^[3]

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1. Harvard Medical School, Boston, MA (United States)
2. Univ. of Maryland, College Park (United States)
3. Massachusetts Inst. of Tech., Cambridge (United States)

The thiol-activated neocarzinostatin chromophore cleaves duplex oligonucleotides containing the sequence -TG{und T}TTGA-, producing 3{prime}-phosphoglycolate and 3{prime}-phosphate fragments at {und T}, indicating the involvement of 4{prime}- as well as 5{prime}-chemistry at this residue. Substitution of deuterium for hydrogen at the C-4{prime} position of the affected {und T} leads to a kinetic isotope effect (k{sub H}/k{sub D}) of 4.0 on the formation of the glycolate-ended product, whereas deuterium at C-5{prime} of the same {und T} reveals k{sub H}/k{sub D} of 1.6 in the formation of the phosphate-ended product. The proportion of the products representing 4{prime}- and 5{prime}-chemistry can be shifted on the basis of isotope selection effects. A second product resulting from 4{prime}-chemistry, the abasic site associated with 4{prime}-hydroxylation, has been identified as an alkali-labile site, and as a pyridazine derivative formed after cleavage by hydrazine. A comparable isotope effect on its production (k{sub H}/k{sub D} = 3.7) relative to that of 3{prime}-phosphoglycolate production is consistent with a common intermediate, a putative 4{prime}-peroxy radical, in their formation. The formation of both products of 4{prime}-chemistry is oxygen-dependent, and the internal partitioning between them (3{prime}-phosphate or 3{prime}-phosphoglycolate) is influenced by thiols. Moreover, the nitroaromatic radiation sensitizer misonidazole can substitute for dioxygen, yielding 3{prime}-phosphoglycolate and alkali-labile 3{prime}-phosphate ends, indicative of 4{prime}-chemistry. In addition to the internal partitioning of 4{prime}-chemistry, thiols also affect the overall extent of cleavage (4{prime} plus 5{prime}) and the relative partitioning between both sites of attack (4{prime} or 5{prime}).

• OSTI ID: 5715443
• Journal Information: Biochemistry; (United States), Vol. 30:8; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
NEOCARCINOSTATIN
BIOLOGICAL EFFECTS
OLIGONUCLEOTIDES
ISOTOPE EFFECTS
ANTIBIOTICS
DEOXYRIBOSE
DEUTERIUM COMPOUNDS
DNA SEQUENCING
PHOSPHORUS 32
THIOLS
ALDEHYDES
ANTI-INFECTIVE AGENTS
ANTINEOPLASTIC DRUGS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOHYDRATES
DAYS LIVING RADIOISOTOPES
DRUGS
HYDROGEN COMPOUNDS
ISOTOPES
LIGHT NUCLEI
MONOSACCHARIDES
NUCLEI
NUCLEIC ACIDS
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PENTOSES
PHOSPHORUS ISOTOPES
RADIOISOTOPES
RADIOMIMETIC DRUGS
SACCHARIDES
STRUCTURAL CHEMICAL ANALYSIS
550201* - Biochemistry- Tracer Techniques