Transient electric birefringence of T-even bacteriophages. III. T2L and T6 with retracted fibers compared with T4B

✍ Scribed by W. Boontje; J. Greve; Joh. Blok

• Publisher: Wiley (John Wiley & Sons)
• Year: 1977
• Tongue: English
• Weight: 1019 KB
• Volume: 16
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1977.360160307

✦ Synopsis

Abstract

Measurements of birefringence are used to study electro‐optical and hydrodynamical properties of the bacteriophages T2 and T6 under conditions in which the fibers are folded back along the tail.

The rotational diffusion coefficients corrected to 25°C and water viscosity (D~25,w~) are 325 ± 12 sec^−1^ and 322 ± 12 sec^−1^, respectively. These values differ significantly from those reported for T4(D~25,w~ = 280 ± 9 sec^−1^). This might be due to a difference in configuration. It could be shown that the orientation of T‐even bacteriophage particles in the electric field is largely due to a permanent dipole moment. This dipole moment can be calculated from the measurements and appeared to be dependent on ionic strength. At low ionic strength (pH 6) the dipole moments of T2 and T6 approach the values 4.1 × 10^−25^ C·m (1.24 × 10^5^ D) and 6.6 × 10^−25^ C·m (2.0 × 10^5^ D), respectively, which is much larger than the value of 0.8 × 10^−25^ C·m (0.24 × 10^5^ D) found for T4. An increase in ionic strength decreases the permanent dipole moment. This effect can be described by a Debye–Hückel model of the screening of surface charges by counterions in the case of T4 and T6. For T2 the picture is more complicated, as an increase in buffer concentration causes a change in configuration.