ISSN:
0022-3832
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The bacteriophages (bacterial viruses) are the largest biologically active agents having known dimensions and particle morphology which have been prepared in a homogeneous state. Because all the bacteriophages have an appendage or “tail”, they offer an interesting system for study in the analytical ultracentrifuge in comparison of the results of direct and indirect methods for estimation of particle size and shape. The sedimentation behavior of phages T5, T6, and T7, all differing in size and morphology, has thus been investigated. Although, under certain conditions, the three viruses sediment with a single sharp boundary, T6 appears to undergo aggregation to form a dimer at neutral pH. The sedimentation rate of the phages is little affected by concentration and is uninfluenced by the centrifugal field, thus indicating the absence of interaction or of particle orientation due to the peculiar morphology. A comparison of estimates of the particle size and weight based on molecular-kinetic constants, electron micrograph dimensions, and unit infectivity yields a good correlation among the results of the direct and indirect physical methods for the quasispherical particle of T7, satisfactory agreement for the large tadpole-shaped particle of T6, but considerable discrepancy for the sperm-shaped particle of T5. It is suggested that the dimensions of T5 based on early electron micrographs are in error. Despite their large size and unusual shape the bacteriophages are amenable to physicochemical study, and each type is as uniform in molecular-kinetic properties as are molecular proteins.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1954.120120131
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