Ferrocytochrome c and deoxyhemoglobin in the reaction with the iron cysteamine nitrosyl complex {Fe2[S(CH2)2NH3]2(NO)4}SO4•2.5H2O

By an example of the iron cysteamine nitrosyl complex {Fe-2[S(CH2)(2)NH3](2)(NO)(4)}SO4 center dot center dot 2.5H(2)O (CAC), it was shown for the first time that the hydrolysis of this NO donor in the presence of ferrocytochrome c (cyt c (2+)) affords the iron nitrosyl complex NO-cyt c (2+), which serves as the NO depot. The rate constant of NO release from CAC was determined from the kinetics of the formation of NO-cyt c (2+). At pH 3.0 the rate constant is (2.7 +/- 0.1)center dot 10(-3) s(-1). Ferrocytochrome c produces a less stabilizing effect on CAC than deoxyhemoglobin (Hb). Thus in the presence of cyt c (2+), the reaction is completed in 1 h, whereas NO is released from a solution of CAC (2 center dot 10(-4) mol L-1) in the presence of Hb during 40 h. The previously unknown stabilization of iron nitrosyl complexes by hemoglobin was found.