MATHEMATICAL-MODELING - OF ELECTROSTATIC FLUCTUATIONS IN SUBTILISIN ACTIVE-SITE

The intensities of electrostatic fluctuations in subtilisin active sit e generated by conformational motion of charged side chains, polar sid e chains and peptide bonds of the main chain are calculated. The compa rative analysis of all these fragments reveals that there are few of t hem which make the main contribution to the total value of the intensi ty, which has been found to be similar to 10(7) g . cm(-1). s(-2). The se are Ser 125, Thr 220 and peptide bonds of aminoacids 125-126, 218-2 19. Our present analysis enables us to compare the relative contributi on of different fragments but we do not pretend to obtain precise abso lute values. The reason for this is the lack of the detailed selective information on the mean - square amplitudes and correlation times of conformational motion of the fragments and on the values of local diel ectric constants in the interior of subtilisin. The possibility for el ectrostatic fluctuations in enzyme active site to be an efficient nons pecific source of substrate activation is discussed.