Binding of actinomycin D to (d(ATCGAT)) sub 2 : NMR evidence of multiple complexes

Journal Article · Tue Jun 13 04:00:00 EDT 1989 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00438a047· OSTI ID:5432972

Zhou, N; James, T L; Shafer, R H ^[1]

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1. Univ. of California, San Francisco (USA)

Actinomycin D (actD) binds to the oligonucleotide (d(ATCGAT)){sub 2} with a hypochromatic and red-shifted visible absorbance band compared to free drug and a CD spectrum with double negative bands at 460 and 385 nm. These spectral features are similar to those of the actD-(d(ATGCAT)){sub 2} complex, while actD-(d(AT){sub 5}){sub 2} gives spectra similar to those of free drug. Upon dilution or raising the temperature, the spectral characteristics accompanying complex formation disappear in the actD-((ATCGAT)){sub 2} sample but remain in the actD-(d(ATGCAT)){sub 2} complex under the same experimental conditions. From NMR spectra of the actD-(d(ATCGAT)){sub 2} complex, three types of signals can be detected below 20{degree}C, one major and two minor ones. At higher temperatures, exchange between the two minor ones becomes fast enough that only one type of minor signal was seen. Partial resonance assignments were made by using 2D nuclear Overhauser effect (NOE) and 2D homonuclear Hartmann-Hahn (HOHAHA) experiments. Proton chemical shift changes of the major complex are consistent with actD chromophore ring intercalation between hexamer base pairs. Data from NOE-detected dipolar interactions between actD and (d(ATCGAT)){sub 2} protons were interpreted in terms of a major complex with the actD chromophore ring system intercalated at the CG position and minor complexes with the drug intercalated off center at the GA positions. While the centrally intercalated complex still exists at a 1:2 (d(ATCGAT)){sub 2}:actD ratio, there is also evidence for a complex consisting of two bound actD molecules per duplex.

• OSTI ID: 5432972
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 28:12; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
ACTINOMYCIN
ANTI-INFECTIVE AGENTS
ANTIBIOTICS
ANTIMITOTIC DRUGS
ANTINEOPLASTIC DRUGS
CHEMICAL BONDS
CHEMICAL REACTIONS
CHEMICAL SHIFT
CLATHRATES
CROSS-LINKING
DICHROISM
DRUGS
MAGNETIC RESONANCE
NUCLEAR MAGNETIC RESONANCE
NUCLEIC ACIDS
OLIGONUCLEOTIDES
ORGANIC COMPOUNDS
OVERHAUSER EFFECT
POLYMERIZATION
RESONANCE
TEMPERATURE DEPENDENCE