Isolation and Purification of Mitochondrial Mn-Superoxide Dismutase from the Gymnosperm Pinus sylvestris L. : PROTEINS, ENZYMES AND METABOLISM

概要

論文の詳細を見る
Manganese superoxide dismutase (Mn-SOD; EC 1.15.1.1) was purified from germinating seeds of Scots pine (Pinus sylvestris L.) 3 days after the start of imbibition. The purification schedule included (NH_4)_2SO_4 fractionation, anion-exchange and hydrophobic-interaction chromatographies and chromatofocusing. Purified Mn-SOD had an apparent specific activity of 4,130 McCord-Fridovich units (mg protein)^<-1>. The molecular mass of the holoenzyme was estimated to be 91 kDa by size-exclusion chromatography, and a molecular mass of 23 kDa was determined by SDS-PAGE. However, isoelectric focusing demonstrated that the purified enzyme consisted of three similarly migrating isoforms, with isoelectric points of approximately 6.5. NH_2-terminal amino acid sequencing of purified Mn-SOD revealed no differences among the three isoforms. The comparison of the first 32 NH_2-terminal amino acids with sequences of NH_2-terminal amino acids of Mn-SODs from angiosperms reflected the phylogenetic distances between Scots pine, which is a gymnosperm, and angiospermic species. Cell fractionation suggested the mitochondrial localization of Mn-SODs and no evidence for glyoxysomal localization was found. Mn-SOD activity was absent from dry seeds. It was detectable at a considerable level after imbibition for 24 h, and it was again absent from 3-week-old seedlings.
日本植物生理学会の論文