Circular dichroism study of the interaction between T4 gene 32 protein and polynucleotides

Journal Article · Sun Jan 01 04:00:00 EST 1978 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00598a022· OSTI ID:5911575

Greve, J; Maestre, M F; Moise, H; Hosoda, J

The interaction of bacteriophage T4 gene 32 coded protein (DNA melting- or unwinding protein) and the synthetic polynucleotides poly(dA), poly(dT), poly(dA) . poly(dT), and poly(d(A-t)) . poly(d(A-T)) was examined by means of circular dichroism spectroscopy. The protein induced strand separation of the double-stranded molecules at temperatures far below the regular melting temperatures. This denaturation is reversible for poly(d(A-T)) . poly(d(A-T)) but irreversible for poly(dA) . poly(dT). In the complexes formed with the protein the single polynucleotide has a conformation in which the bases are stacked. This conformation closely resembles that of one strand of a poly(d(A-T)) . poly(d(A-T)) molecule at high LiCl concentration. To arrive at this conclusion qualitative rules for the interpretation of the polynucleotide circular dichroism spectra were dervied. These rules are: (a) Upon strand separation the minimum in the CD spectrum near 250 nm shifts by about 3 nm to the red. (b) The degree of base stacking in a single-stranded polynucleotide follows from the depth of the minimum in the circular dichroism spectrum near 250 nm. (c) The type of conformation of the single-stranded polynucleotide can be determined from a comparison of the long wavelength part of the circular dichroism spectra of single- and double-stranded polynucleotides. This part of the spectrum has the same shape for a double-stranded and a single-stranded molecule provided the conformations of the separate strands are equal.

• Research Organization: Univ. of California, Berkeley
• OSTI ID: 5911575
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 17:5; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
550300 -- Cytology
59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL COMPOUNDS
BACTERIOPHAGES
CHLORIDES
CHLORINE COMPOUNDS
DICHROISM
DNA
HALIDES
HALOGEN COMPOUNDS
LITHIUM CHLORIDES
LITHIUM COMPOUNDS
LITHIUM HALIDES
MELTING POINTS
MICROORGANISMS
MOLECULAR STRUCTURE
NUCLEIC ACID DENATURATION
NUCLEIC ACIDS
NUCLEOTIDES
ORGANIC COMPOUNDS
PARASITES
PHYSICAL PROPERTIES
PROTEINS
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE
VIRUSES