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Hydrodynamics, size, and shape of bacteriophage T4D tails and baseplates
Author(s) -
Benbasat Julyet A.,
Bloomfield Victor A.
Publication year - 1982
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360210406
Subject(s) - vertex (graph theory) , diffusion , chemistry , electron microscope , hexagonal crystal system , molecular physics , microscopy , geometry , physics , optics , crystallography , thermodynamics , mathematics , combinatorics , graph
We have used translational diffusion coefficient measurements and subunit hydrodynamic theory to determine the dimensions and shape of bacterioophage T4D baseplates and tails. The diffusion coefficient of the baseplate, measured by quasielastic laser light scattering (QLS), was determined previously by Wagenknecht and Bloomfield to be D = 8.56 × 10 −8 cm 2 /s. For the tail, we found D = 5.88 × 10 −8 cm 2 /s by QLS, and D = 6.02 × 10 −8 cm 2 /s by combining sedimentation coefficient and molecular weight in the Svedberg equation. These values, which have an uncertainty of ±2.7%, when combined with subunit hydrodynamic theory, enabled us to refine estimates of dimensions obtained by electron microscopy. For the hexagonal baseplate, the vertex‐to‐vertex distance is about 480 Å, the thickness is 160 Å, and there are six extended short fibers 320‐Å long and 40 Å in diameter. When a baseplate of these dimensions is attached to a tail tube‐sheath‐connector complex 1050‐Å long and 240 Å in diameter, the calculated D is 5.93 × 10 −8 cm 2 /s, within 1% of experiment. This combined use of electron microscopy and hydrodynamics, using the former to ascertain shape, and the latter to obtain solution dimensions, is a powerful approach to the structure of biomolecular complexes.