Untersuchung des Schwingungsanteils und des Kristallgitterfehleranteils des Temperaturfaktors in Myoglobin durch Vergleich von Mossbauer-absorptionsmessungen mit Rontgenstrukturdaten
Abstract
The mean square displacement (x2) from the theoretical lattice point, obtained from X-ray structure data for myoglobin crystals, is compared with the corresponding value, (x2)T, measured by Mossbauer experiments on the iron in myoglobin crystals. (x2)T depends only on the vibrations of the lattice. The value (x2), however, which is obtained from X-ray data contains a contribution due to lattice faults in addition to the contribution due to vibrations. (x2) - (x2)T = (x2)S is then the contribution due to lattice faults alone. The experimental values are (x2) = 13.2 x 10-2 A2 and (x2)T = 8.6 x 10-2 A2 giving (x2)S = 4.6 x 10-2 A2. The same comparison was made for K3Fe(CN)6 and for hemine. Here (x2) was roughly equal to (x2)T. In addition the temperature dependence of (x2)T was measured for myoglobin crystals. A new procedure is described for the substitution of the isotope 57Fe required for Mossbauer measurements for the natural iron in myoglobin.
