THE EFFECTS OF pH AND TEMPERATURE ON THE KINETICS OF THE PHOSPHORYLASE REACTION

tary replication, we have to confront the double difficulty of unwinding and rewinding. The present mechanism is no exception; the parent DNA unwinds exactly No turns, and the daughters rewind exactly No turns, No being the winding number of the DNA molecule. However, the difficulty is reduced to a minimum by rewinding immediately after unwinding so that there is no large number of unwound turns to cause difficulty both in unwinding and rewinding. In the previous paper, it is stated that the unwinding angular velocity W(t) is a monotonically decreasing function of time or of the number of turns unwound. In the present mechanism, the unwound turns are removed by the rewinding of the daughters so that the unwinding is operated at all times near the starting point of the c(t) curve, and the average value of W(t) is very close to its maximum value co(O). Thus, the unwinding time in the present mechanism is very close to the lower limit T, in the previous paper. Unwinding in vivo is therefore much faster than in vitro.