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Heterogeneous glycosylation of cationic peanut peroxidase

1994; NRC Research Press; Volume: 72; Issue: 9-10 Linguagem: Inglês

10.1139/o94-055

1208-6002

Li Wan, Mark Gijzen, Robert B. van Huystee,

Biopolymer Synthesis and Applications

Cationic peanut peroxidase (CPrx) from a cell suspension culture is N-glycosylated at Asn60, Asn144, and Asn185. All three N-glycans are complex type and galactose rich, and show heterogeneity in length and ConA (concanavalin A) binding property. The glycan heterogeneity causes a polymorphism of the enzyme. Based on its behavior on ConA columns, CPrx can be grouped into two fractions: nonbinding (CPrx − ) and binding (CPrx + ) types. A synchronously cosecreted β-galactosidase has been discovered in the culture medium; there are two isozymes of 60 kDa (pI 7.3) and 66 kDa (pI 7.6). This β-galactosidase has been partially purified by a combination of ion-exchange and size-exclusion chromatographies and preparative isoelectrofocusing. In vitro experiments indicate that the cosecreted β-galactosidase is able to convert peroxidase from CPrx − to CPrx + and may, to some extent, contribute to the glycan heterogeneity of peroxidase in the cell culture.Key words: peroxidase, peanut, glycan, heterogeneity, β-galactosidase.