TY - JOUR
T1 - Tertiary and quaternary structure of tobacco mosaic virus and protein. II. Emission, excitation, polarization and position of 2-p-toluidinylnaphthalene-6-sulfonate binding
AU - Guttenplan, J. B.
AU - Calvin, M.
N1 - Funding Information:
This work was supported, in part, by the U.S. Atomic Energy Commission. One of us (J.B.G.) is a National Cancer Institute post-doctoral fellow. The authors wish to thank Dr H. Fraenkel-Conrat for many helpful discussions and his aid in initiating this study.
PY - 1973/10/18
Y1 - 1973/10/18
N2 - The emission, excitation and polarization spectra of tobacco mosaic virus protein were identical for the aggregated protein and disaggregated protein (A Protein) with the exception that the quantum yield of fluorescence decreased 25% on aggregation. This decrease in the absence of other spectral changes suggests a quenching interaction between adjacent subunits. The aggregation apparently produces, at most, minor conformational changes within subunits. The polarization of fluorescence is low but does not decrease on aggregation, indicating that energy migrates efficiently within subunits but not between subunits. Intersubunit space must be large, relative to intrasubunit space. Fluorescence from the tyrosine residues in tobacco mosaic virus protein is not observable, and evidence from the excitation spectrum of tobacco mosaic virus protein is given which suggests that tyrosine energy is efficiently transferred to the tryptophans in tobacco mosaic virus protein. These results and the low polarization indicate that tobacco mosaic virus protein subunits are rather compact. 2-p-Toluidinylnaphthalene-6-sulfonate (TNS), a hydrophobic probe, bound more strongly to aggregated protein than to A Protein. This was shown to be due to the charge change associated with the aggregation as TNS sulfonamide (TNSA) a neutral probe, was bound with equal efficiency to A Protein and aggregated protein. As exposure of the intersubunit regions led to no increase in hydrophobic binding of TNS or TNSA, the hydrophobicity of the intersubunit surface is weak.
AB - The emission, excitation and polarization spectra of tobacco mosaic virus protein were identical for the aggregated protein and disaggregated protein (A Protein) with the exception that the quantum yield of fluorescence decreased 25% on aggregation. This decrease in the absence of other spectral changes suggests a quenching interaction between adjacent subunits. The aggregation apparently produces, at most, minor conformational changes within subunits. The polarization of fluorescence is low but does not decrease on aggregation, indicating that energy migrates efficiently within subunits but not between subunits. Intersubunit space must be large, relative to intrasubunit space. Fluorescence from the tyrosine residues in tobacco mosaic virus protein is not observable, and evidence from the excitation spectrum of tobacco mosaic virus protein is given which suggests that tyrosine energy is efficiently transferred to the tryptophans in tobacco mosaic virus protein. These results and the low polarization indicate that tobacco mosaic virus protein subunits are rather compact. 2-p-Toluidinylnaphthalene-6-sulfonate (TNS), a hydrophobic probe, bound more strongly to aggregated protein than to A Protein. This was shown to be due to the charge change associated with the aggregation as TNS sulfonamide (TNSA) a neutral probe, was bound with equal efficiency to A Protein and aggregated protein. As exposure of the intersubunit regions led to no increase in hydrophobic binding of TNS or TNSA, the hydrophobicity of the intersubunit surface is weak.
UR - http://www.scopus.com/inward/record.url?scp=0015817456&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0015817456&partnerID=8YFLogxK
U2 - 10.1016/0005-2795(73)90306-1
DO - 10.1016/0005-2795(73)90306-1
M3 - Article
C2 - 4765094
AN - SCOPUS:0015817456
SN - 0005-2795
VL - 322
SP - 301
EP - 320
JO - BBA - Protein Structure
JF - BBA - Protein Structure
IS - 2
ER -