Partial Characterization and Subcellular Localization of Three α-Glucosidase Isoforms in Pea (Pisum sativum L.) Seedlings | Zendy

Eric P. Beers | Zendy; Stanley H. Duke | Zendy; Cynthia A. Henson | Zendy

Open Access

Partial Characterization and Subcellular Localization of Three α-Glucosidase Isoforms in Pea (Pisum sativum L.) Seedlings

Author(s) -

Eric P. Beers,

Stanley H. Duke,

Cynthia A. Henson

Publication year - 1990

Publication title -

plant physiology

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 3.554

H-Index - 312

eISSN - 1532-2548

pISSN - 0032-0889

DOI - 10.1104/pp.94.2.738

Subject(s) - pisum , sativum , apoplast , biochemistry , maltose , enzyme , isozyme , biology , gene isoform , molar concentration , chenopodiaceae , chemistry , botany , cell wall , gene , organic chemistry

Three isoforms of alpha-glucosidase (EC 3.2.1.20) have been extracted from pea (Pisum sativum L.) seedlings and separated by DEAE-cellulose and CM-Sepharose chromatography. Two alpha-glucosidase isoforms (alphaG1 and alphaG2) were most active under acid conditions, and appeared to be apoplastic. A neutral form (alphaG3) was most active near pH 7, and was identified as a chloroplastic enzyme. Together, the activity of alphaG1 and alphaG2 in apoplastic preparations accounted for 21% of the total acid alpha-glucosidase activity recovered from pea stems. The vast majority (86%) of the apoplastic acid alpha-glucosidase activity was due to alphaG1. The apparent K(m) values for maltose of alphaG1 and alphaG2 were 0.3 and 1.3 millimolar, respectively. The apparent K(m) for maltose of alphaG3 was 33 millimolar. The respective native molecular weights of alphaG1, alphaG2, and alphaG3 were 125,000, 150,000, and 110,000.

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