CONFORMATIONAL CALCULATIONS ON THE ALA14-PRO27 LC1 SEGMENT OF RABBIT SKELETAL MYOSIN

In order to define the conformational characteristics of a singular Ala14-Pro27 segment in myosin LC1, conformational calculations were performed using the Simplex algorithm of Nelder and Mead (Computer J. 7 (1965) 308-313) in the ACME program proposed by Tournarie (J. Appl. Cryst. 6 (1973) 309-346). The (Ala-Pro) n = 1 unit was assigned a given conformation x; the conformation energy was then minimized for n = 1 to n = 7 by adjusting structural parameters (angle values). Similarly, 13 different possible conformations were optimized and compared, showing that a (β2R)7 conformation is favored by about 20 kcal per mol over the next most probable conformation (C7R)7. In the β2R conformation, the (Ala-Pro)7 segment is a wide helix, 15 Å in length and 8.65 Å in diameter, while the C7R conformation results in a semi-extended structure of 25 Å long, with an approximate diameter of 6 Å. These characteristics are in agreement with available experimental data and putative functions of the LC1 N-terminus. © 1990.