Reassessment of copper stoichiometry in ascorbate oxidase |
| |
Authors: | L Morpurgo I Savini G Gatti M Bolognesi L Avigliano |
| |
Institution: | Dipartimento di Scienze Biochimiche, Università di Roma, La Sapienza, Italy. |
| |
Abstract: | A very pure ascorbate oxidase solution was obtained by dissolving a crystalline sample of the enzyme. The ratio between 280 and 610 nm absorbancies was 22.5. It contained 8.0 +/- 0.2 Cu ions, 50% EPR detectable, per dimeric molecule (140,000 M.W.) with a molar extinction coefficient of 10,000 cm-1 at 610 nm. Two Cu ions were removed by treatment with N,N-diethyldithiocarbamate. The optical blue absorption band was unaffected, while two EPR detectable Cu ions were lost, with disappearance of the type 2 Cu signal. It is concluded that native ascorbate oxidase contains two type 1, two type 2, and four type 3 Cu ions. |
| |
Keywords: | |
|
|