title: Purification of an iron-containing superoxide dismutase from a citrus plant, Citrus limonum R.
abstract: A cyanide-insensitive superoxide dismutase was purified to apparent homogeneity from lemon leaves (Citrus limonum R). The enzyme was isolated from leaf extracts by ammonium sulfate salting-out, and ion-exchange, gel filtration and hydroxylapatite column chromatography. The purified Fe-SOD had a specific activity of about 1,500 U/mg and represents approximately 1.6% of the total soluble protein in lemon leaf extracts. A molecular weight of 47,500 was determined for the enzyme. Analytical gel electro-focusing of the purified preparation revealed the presence of two isozymes with pI values of 5.13 and 4.98. Metal analysis showed the presence of 1 g-atom of iron and 0.5 g-atom of manganese per mol of enzyme. The visible and UV absorption spectra of the Citrus enzyme were similar to those reported for other iron-containing SODs from different origins. The significance of the presence of Fe-SOD in higher plants is briefly discussed.
authors.affiliation: Unidad de Alimentación y Desarrollo de la Planta, Centro de Edafología y Biología, CSIC, Murcia, Spain.
authors.forename: M S
authors.initials: MS
authors.lastname: Almansa
authors.forename: J M
authors.initials: JM
authors.lastname: Palma
authors.forename: J
authors.initials: J
authors.lastname: Yáñez
authors.forename: L A
authors.initials: LA
authors.lastname: del Río
authors.forename: F
authors.initials: F
authors.lastname: Sevilla
mesh_terms: D002852:Chromatography, Ion Exchange; D002957:Citrus / Q000201:enzymology*; D007501:Iron / Q000032:analysis; D010940:Plant Proteins / Q000302:isolation & purification*; D013482:Superoxide Dismutase / Q000302:isolation & purification*
chemical_list: D010940:Plant Proteins; D007501:Iron; D013482:Superoxide Dismutase