Reports on the kinetics of the autoxidation of aqueous nitric oxide are discussed. It is concluded that the correct rate law is -d[NO]/dt = 4kaq[NO]2[O2] with kaq = 2 x 10(6) M-2.s-1 at 25 degrees c and that a recent report of a rate law zero order in NO is incorrect.

Hydrogen sulfide (H2S) is an endogenously generated and putative signaling/effector molecule. Despite its numerous reported functions, the chemistry by which it elicits its functions is not understood. Moreover, recent studies allude to the existence of other sulfur species besides H2S that may play critical physiological roles. Herein, the basic chemical biology of H2S as well as other related or derived species is discussed and reviewed. This review particularly focuses on the per- and polysulfides which are likely in equilibrium with free H2S and which may be important biological effectors themselves.