Time-resolved Raman detection of .nu.(Fe-O) in an early intermediate in the reduction of oxygen by cytochrome oxidase

Cytochrome oxidase contains four redox-active centers per functional unit. These reducing equivalents are transferred to the binuclear cyt a{sub 3}{hor ellipsis}Cu{sub B} center, which binds O{sub 2} and reduces it to H{sub 2}O. Although the reaction between O{sub 2} and cytochrome oxidase occurs too quickly to be studied by conventional stopped-flow techniques, Gibson and Greenwood showed that photolysis of the cytochrome a{sub 3}{sup 2+}-CO complex of the enzyme in the presence of O{sub 2} could be used to circumvent this limitation. The authors have developed techniques that allow them to carry out low-frequency Raman detection under flow/flash conditions; here they report v(Fe{sup 2+}-O) for an early intermediate in the cytochrome oxidase/dioxygen reaction.