  Universal intermittent dynamics in a random catalytic reaction network,
induced by smallness in the molecule number is reported. Stochastic simulations
for a random catalytic reaction network subject to a flow of chemicals show
that the system undergoes a transition from a stationary to an intermittent
reaction phase when the flow rate is decreased. In the intermittent reaction
phase, two temporal regimes with active and halted reactions alternate. The
number frequency of reaction events at each active regime and its duration time
are shown to obey a universal power laws with the exponents 4/3 and 3/2,
respectively. These power laws are explained by a one-dimensional random walk
representation of the number of catalytically active chemicals. Possible
relevance of the result to intra-cellular reaction dynamics is also discussed.
