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 1, two type 2, and four type 3 Cu ions. © 1988 Academic Press, Inc.
Morpurgo, L., Savini, I., Gatti, G., Bolognesi, M., Avigliano, L. (1988). Reassessment of copper stoichiometry in ascorbate oxidase. BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, 152(2), 623-628.
Reassessment of copper stoichiometry in ascorbate oxidase
SAVINI, ISABELLA;AVIGLIANO, LUCIANA
1988-01-01
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 1, two type 2, and four type 3 Cu ions. © 1988 Academic Press, Inc.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
