Table 8. A comparison of the estimated stretching and bending constants for the reduced state of the 4-Cys-[2Fe-2S] and Rieske structures, based on calculated normal modes.
Force constant (reduced) | ||||
---|---|---|---|---|
4-Cys-[2Fe-2S] | Rieske | |||
Mode | [mdyne/Å] | [kcal/molÅ2] | [mdyne/Å] | [kcal/molÅ2] |
K(Fe-S(b)):His | 1.353 | 195. | 0.949 | 137. |
K(Fe-S(b)):Cys | 1.353 | 195. | 0.874 | 126. |
K(Fe-S(t)) | 0.587 | 84. | 1.169 | 168. |
K(Fe-N(t)) | - | - | 0.411 | 59. |
H(Fe-S(b)-Fe) | 0.303 | 44. | 0.373 | 54. |
H(S(b)-Fe-S(b)) | 0.410 | 59. | 0.373 | 54. |
H(S(b)-Fe-S(t)) | 0.460 | 66. | 0.335 | 48. |
H(S(t)-Fe-S(t)) | 0.460 | 66. | 0.335 | 48. |
H(S(b)-Fe-N(t)) | - | - | 0.401 | 58. |
H(N(t)-Fe-N(t)) | - | - | 0.401 | 58. |
K(Fe-Fe) | 0.164 | 24. | 0.246 | 35. |
The notation K and H indicate stretching and bending, respectively.