SEDIMENTATION AND BIOLOGICAL PROPERTIES OF T-PHAGES OF ESCHERICHIA COLI.

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Abstract The sedimentation, morphological, and some biological properties of T413 and T4Bo 1 were investigated. It was found that T4B and T4B o1 had a single sedimentation coefficient of 1000 S under normal conditions. However, in the presence of l -tryptophan, the sedimentation coefficient was 900 S for both these particles. The protein coats or “ghosts” of T4B and T4Bo 1 gave a similar response to l -tryptophan. This change in sedimentation behavior was correlated with a change in configuration of the tail fibers. The tail fibers at the distal end of the tail were extended only in the presence of l -tryptophan. No change in head length was noted. It was pointed out that this small difference in sedimentation coefficient in no way corresponded to the 43% difference obtained with T2L subjected to pH, temperature, or cation modifications. No differences in the head protein subunits of T2L, T4B, or T4Bo 1 were detected with respect to sedimentation coefficient, molecular weight, and end terminal patterns of their amino acid complements. Differences were observed with respect to the permeability properties of T4B and T4B o1 . T4B was susceptible to osmotic shock in Na 2 SO 4 but not in sucrose. T4B o1 was susceptible to osmotic shock in sucrose but not in Na 2 SO 4 . Intermediate degrees of susceptibility were obtained for both bacteriophages in glycerol. The flotation densities in D 2 O of T4B and T4B o1 were determined: T4B had a density of 1.60 g/ml whereas T4Bo 1 had a density of 1.81 g/ml. l -Tryptophan had no effect on these flotation densities. Additional differences between T4B and T4Bo 1 were discerned after incubation with 0.5 M l -cysteine. It was found that T4B was then able to kill bacteria and be inactivated by Cd(CN) 3 − , both in the absence of l -tryptophan. The l -tryptophan requirement of T4Bo 1 for both these processes was not altered after l -cysteine treatment. The sedimentation behavior of T3 and T5 was also studied, and the general sedimentation behavior and corresponding head form were discussed with regard to the biological role the phage head plays during infection.