TY - JOUR
T1 - Structure and physico-chemical properties of bacteriophage G. III. A homogeneous DNA of molecular weight 5 × 108
AU - Donelli, G.
AU - Dore, E.
AU - Frontali, C.
AU - Grandolfo, M. E.
PY - 1975/6/5
Y1 - 1975/6/5
N2 - The physico-chemical properties of the DNA released from bacteriophage G (active on Bacillus megatherium) are described. Phage G, an unusually large bacteriophage, has a nucleic acid content of 4 to 6 × 108 daltons. Sedimentation velocity analysis at low angular speed and examination by electron microscopy, indicate that a single DNA molecule, sedimenting with s20, w
0 = 125 ± 1.5 S and at least 200 ± 20 μm long, is released upon thermal or osmotic shock. Melting temperature data and chromatographic analysis indicate a mean base composition of 70% A + T. CsCl and Cs2SO4 buoyant density data, circular dichroism spectra and sensitivity to specific nucleases indicate that phage G DNA is similar to the DNAs from T-even phages and is more glucosylated than phage T6 DNA. Direct glucose determination indicates a 185% molar ratio of glucose to cytosine. Linear density extrapolated from literature data and contour length measurement yield a lower limit for the molecular weight of phage G DNA of 4.9 × 108. Comparison of this value with the s20,w
0 measured with the analytical ultracentrifuge seems to confirm the validity of the empirical relationship proposed by Freifelder (1970), between s20, w
0 and molecular weight, over a larger range than that previously known. A possible systematic error in defect in length determination, however, prevents a discrimination between this and other empirical formulae proposed by various authors, which predict a molecular weight that is 20 to 25% higher.
AB - The physico-chemical properties of the DNA released from bacteriophage G (active on Bacillus megatherium) are described. Phage G, an unusually large bacteriophage, has a nucleic acid content of 4 to 6 × 108 daltons. Sedimentation velocity analysis at low angular speed and examination by electron microscopy, indicate that a single DNA molecule, sedimenting with s20, w
0 = 125 ± 1.5 S and at least 200 ± 20 μm long, is released upon thermal or osmotic shock. Melting temperature data and chromatographic analysis indicate a mean base composition of 70% A + T. CsCl and Cs2SO4 buoyant density data, circular dichroism spectra and sensitivity to specific nucleases indicate that phage G DNA is similar to the DNAs from T-even phages and is more glucosylated than phage T6 DNA. Direct glucose determination indicates a 185% molar ratio of glucose to cytosine. Linear density extrapolated from literature data and contour length measurement yield a lower limit for the molecular weight of phage G DNA of 4.9 × 108. Comparison of this value with the s20,w
0 measured with the analytical ultracentrifuge seems to confirm the validity of the empirical relationship proposed by Freifelder (1970), between s20, w
0 and molecular weight, over a larger range than that previously known. A possible systematic error in defect in length determination, however, prevents a discrimination between this and other empirical formulae proposed by various authors, which predict a molecular weight that is 20 to 25% higher.
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U2 - 10.1016/0022-2836(75)90321-6
DO - 10.1016/0022-2836(75)90321-6
M3 - Article
C2 - 810596
AN - SCOPUS:0016759879
VL - 94
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
SN - 0022-2836
IS - 4
ER -