TY - JOUR
T1 - Conformational substates in a protein
T2 - structure and dynamics of metmyoglobin at 80 K.
AU - Hartmann, H.
AU - Parak, F.
AU - Steigemann, W.
AU - Petsko, G. A.
AU - Ponzi, D. R.
AU - Frauenfelder, H.
PY - 1982/8
Y1 - 1982/8
N2 - The crystal structure of sperm whale metmyoglobin has been determined at 80 K to a resolution of 2A. The overall structure at 80 K is similar to that at 300 K except that the volume is smaller. Refinement of the structure by the method of restrained least squares (current R = 0.175) permits the assignment of isotropic atomic mean-square displacements to all nonhydrogen atoms. Comparison with the values obtained earlier at 250-300 K indicates that the protein at 80 K is more rigid. The average experimentally determined Debye-Waller factor, B, for the protein is 14A2 at 300 K and 5A2 at 80 K. Plots of backbone mean-square displacement vs. temperature show a discontinuity of slope for at least one-third of all residues. This behavior is in good agreement with the temperature dependence of the mean-square displacement of the heme iron as measured by Mössbauer absorption. The magnitudes of the smallest mean-square displacements observed at 80 K indicate that intramolecular motions can be frozen out to a surprisingly large degree. Even at 80 K, however, some atoms in myoglobin still have mean-square displacements greater than 0.1A2, thus providing evidence for conformational substates.
AB - The crystal structure of sperm whale metmyoglobin has been determined at 80 K to a resolution of 2A. The overall structure at 80 K is similar to that at 300 K except that the volume is smaller. Refinement of the structure by the method of restrained least squares (current R = 0.175) permits the assignment of isotropic atomic mean-square displacements to all nonhydrogen atoms. Comparison with the values obtained earlier at 250-300 K indicates that the protein at 80 K is more rigid. The average experimentally determined Debye-Waller factor, B, for the protein is 14A2 at 300 K and 5A2 at 80 K. Plots of backbone mean-square displacement vs. temperature show a discontinuity of slope for at least one-third of all residues. This behavior is in good agreement with the temperature dependence of the mean-square displacement of the heme iron as measured by Mössbauer absorption. The magnitudes of the smallest mean-square displacements observed at 80 K indicate that intramolecular motions can be frozen out to a surprisingly large degree. Even at 80 K, however, some atoms in myoglobin still have mean-square displacements greater than 0.1A2, thus providing evidence for conformational substates.
UR - http://www.scopus.com/inward/record.url?scp=0020170342&partnerID=8YFLogxK
U2 - 10.1073/pnas.79.16.4967
DO - 10.1073/pnas.79.16.4967
M3 - Article
C2 - 6956905
AN - SCOPUS:0020170342
SN - 0027-8424
VL - 79
SP - 4967
EP - 4971
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 16
ER -