Nitric oxide metal centers, binds

Nitric oxide binds to the Cu(II) ion in the binuclear center of fully oxidized cytochrome oxidase (Brudvig et al., 1980). The binding of NO creates an even spin copper center and effectively breaks the spin coupling between the heme and copper metal ions. As a result, the high-spin heme EPR signal is visible at g = 6. 

Nitric oxide adds to many metal centers, and the data are particularly abundant because of the stability and ease of handling of NO solutions. Several review articles have been published on aspects of this subject recently.143 149 In many cases the reactions are reversible, so binding equilibrium constants and rate constants for... 

Borovik and co-workers (29-31) developed porous organic materials for reversible binding of CO, O2, and NO by means of gas chemical coordination to the metal centers. For immobihzation of metal centers, templated copolymerization was employed (Fig. 7). Material 14, for example, contained immobilized four-coordinate Co(II) centers, and the cobalt concentration ranged from 180 to 230 mol g with an average pore diameter of 25 A (31). Polymer 14 bound NO in toluene solution and even on the air-solid interphase, but was relatively inert toward other biologically important gases O2, CO2, and CO. Nitric oxide could be slowly released from 14 under ambient conditions. For example, after 30 days 80% of NO was lost. Heating the sample accelerated the gas release. 

SO2 and CO, CO2, N2O, NO2, and H2O. Lippard and coworkers also utilized the Lewis acid-base interaction for fluorescent detection of nitric oxide (NO). Fluorophores (dansylimidazole or dansylpiperazine) bind to the axial site of the metal center in a dirhodium tetracarboxylate complex. Displacement of fluorophores by NO causes a fluorescence change. 

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