Molecular Properties of Three Soluble Invertase Forms from Lilium longiflorum Flower Buds

Abstract

Three soluble invertase isoforms from Lilium longiflorum flower buds that had been separated by DEAE-Sephacel chromatography were purified to near homogeneity by further chromatography on hydroxylapetite, Con-A sepharose, phenyl agarose, and Sephacryl S-200 gel filtration. Nondenaturing polyacrylamide gel electrophoresis (PAGE) gave a single band in all three invertases that corresponded to a band of invertase activity in a duplicate gel. The SDS-PAGE of the purified invertase I resulted in a single band with apparent relative molecular mass of 78 kDa. Invertase II and III were resolved to a similar polypeptide pattern by SDS-PAGE with three bands of 54, 52, and 24 kDa. Antiserum of tomato acid invertase cross-reacted with all three invertase protein bands. Antiserum of wheat coleoptile acid invertase cross-reacted only with 54 and 52 kDa bands of invertase II and III but did not recognize invertase I protein. Con-A peroxidase was bound to invertase I protein and all three protein bands of invertase II and III, suggesting that all proteins were glycosylated. Invertase I protein could be completely deglycosylated by incubating with peptide-N-glycosidase F to result in a peptide of 75 kDa. Invertase II and III were partially deglycosylated by peptide-N-glycosidase F resulting proteins bands of 53, 51, 50, and 22 kDa.