抄録
Modification of 14S dynein with TNBS, an amino group-blocking reagent with high specificity, enhanced the ATPase activity up to 1.4 times. If ATP was present during preincubation for the modification, the TNBS-induced enhancement was repressed to 1.1 times. It was found that the presence of ATP caused a decrease in the number of TNP groups incorporated into the protein. On the other hand, modification of SH groups of 14S dynein was confirmed to give rise to only monotonic inhibition.
The 30S dynein ATPase activity increased 3.8-fold for Mg activation and 5.7-fold for Ca activation on treatment with TNBS. The enhancement was greater than that produced by the modification of SH groups. This enhancement of 30S dynein ATPase activity by TNBS treatment was also repressed to some extent by the presence of ATP during preincubation for the modification. However, the inhibition of the ATPase activity at higher concentrations of TNBS was not suppressed by the presence of ATP, whereas ATP-induced protection of the activity was clearly observed in the modification of SH groups at higher concentrations of NEM (Shimizu, T. & Kimura, I. (1977) J. Biochem. 82, 165-173).
Treatment with showdomycin, which is a maleimide derivative of ribose, caused a small enhancement of 30S dynein ATPase activity (up to 1.5-fold). The reason for this small enhancement is discussed in relation to the structures of chemical modifiers and the reactivity of SH groups of 30S dynein.
