Thermal difference circular dichroism of Pf1 filamentous virus and effects of mercury(II), silver(I), and copper(II)

Journal Article · Tue May 17 00:00:00 EDT 1988 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00410a010· OSTI ID:6936318

Casadevall, A; Day, L A

The circular dichroism (CD) of Pf1 filamentous virus has been examined over the temperature range 0-40/sup 0/C, in the absence and presence of Hg(II), Ag(I), and Cu(II). Thermal difference CD spectra were obtained by subtraction of spectra recorded above and below a thermally induced structure transition near 12/sup 0/C. The thermal difference spectra look like they arise from shifts in two exciton bands, one centered at 230 nm and the other at 290 nm. The amplitudes on either side of a crossover at 230 nm are 10 times those of a crossover at 290 nm. It is proposed that the difference spectra result from thermally induced shifts in coupled oscillator interactions between Tyr/sub 40/ residues of the coat protein and the guanine and cytosine bases of the DNA. Metal ions can reduce or block these shifts. The changes in ellipticities at 220, 237, and 270 nm induced by changing the temperature have inflections near 12/sup 0/C. Ag(I) and Hg(II), which are known to bind to the DNA bases in Pf1, reduce or eliminate the inflections in the thermal profiles, depending on the metal ion type and concentration. Cu(II) ions do not affect the profiles. The spectral changes and the effects of the metal ions indicate intimate contact between the DNA bases and the protein subunits in the virion.

• Research Organization: Public Health Research Institute of the City of New York, NY (USA)
• OSTI ID: 6936318
• Journal Information: Biochemistry; (United States), Vol. 27:10
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
METALS
BIOLOGICAL EFFECTS
VIRUSES
DICHROISM
TEMPERATURE EFFECTS
COPPER COMPOUNDS
MERCURY COMPOUNDS
SILVER COMPOUNDS
ELEMENTS
MICROORGANISMS
PARASITES
TRANSITION ELEMENT COMPOUNDS
560300* - Chemicals Metabolism & Toxicology
560200 - Thermal Effects