  A master equation describing the evolution of averaged molecular state
occupancies in molecular systems where alternation of molecular energy levels
is caused by discrete dichotomous and trichotomous stochastic fields, is
derived. This study is focused on the kinetics of quasi-isoenergetic transition
processes in the presence of moderately high frequency stochastic field. A
novel physical mechanism for temperature-independent transitions in flexible
molecular systems is proposed. This mechanism becomes effective when the
conformation transitions between quasi-isoenergetic molecular states take
place. At room temperatures, stochastic broadening of molecular energy levels
predominates the energy of low frequency vibrations accompanying the
transition. This leads to a cancellation of the temperature dependence in the
stochastically averaged rate constants. As examples, physical interpretations
of the temperature-independent onset of P2X$_3$ receptor desensitization in
neuronal membranes, as well as degradation of PER2 protein in embrionic
fibroblasts, are provided.
