Purification and characterization of isoforms of β-galactosidases in mung bean seedlings

Sing Chung Li, Jiahn Wern Han, Kuan Chung Chen, Ching San Chen

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

Five isoforms of β-galactosidase (EC 3.2.1.23), designated as β-galactosidases I-V, were isolated from five-day-old mung bean (Vigna radiata) seedlings. β-Galactosidases II and III were purified to electrophoretic homogeneity by a procedure involving acid precipitation, ammonium sulfate fractionation, chromatography on diethylaminoethyl-cellulose (DEAE-Cellulose) and con A-Sepharose, and chromatofocusing. β-Galactosidases I, II and III have the same molecular mass of 87 kDa, comprising two non-identical subunits with molecular masses of 38 and 48 kDa, while β-galactosidases IV and V have molecular masses of 45 and 73 kDa, respectively. All the enzymes were active against p-nitrophenyl-β-D-galactoside, and to a lesser extent, p-nitrophenyl-α-L-arabinoside and p-nitrophenyl-β-D-fucoside. The enzymes were inhibited by D-galactono-1,4-lactone, D-galactose, Hg2+, Ag+ and sodium dodecyl sulfate (SDS). β-Galactosidases I, II and III were shown to be competitively inhibited by either D-galactono-1, 4-lactone or D-galactose. Isoforms I, II and III have a common optimal pH of 3.6, while isoforms IV and V have pH optima at 3.8 and 4.0, respectively. Isoelectric points of isoforms I, II and III were 7.7, 7.5 and 7.3, respectively. Double immunodiffusion analysis indicated that β-galactosidases I, II, III and V are immunologically similar to each other, while β-galactosidase IV shares partially identical antigenic determinants with the other four isoforms. The purified β-galactosidases II and III were capable of releasing D-galactose residue from the hemicellulose fraction isolated from mung bean seeds.

Original languageEnglish
Pages (from-to)349-359
Number of pages11
JournalPhytochemistry
Volume57
Issue number3
DOIs
Publication statusPublished - Jun 2001
Externally publishedYes

Fingerprint

Galactosidases
galactosidases
mung beans
Seedlings
Purification
Protein Isoforms
seedlings
Molecular mass
Galactose
galactose
molecular weight
lactones
Vigna
Galactosides
galactosides
Immunodiffusion
Vigna radiata
acid deposition
Isoelectric Point
Ammonium Sulfate

Keywords

  • β-Galactosidase
  • Enzyme purification
  • Leguminosae
  • Natural substrates
  • Vigna radiata

ASJC Scopus subject areas

  • Plant Science
  • Biochemistry
  • Molecular Biology
  • Organic Chemistry
  • Drug Discovery

Cite this

Purification and characterization of isoforms of β-galactosidases in mung bean seedlings. / Li, Sing Chung; Han, Jiahn Wern; Chen, Kuan Chung; Chen, Ching San.

In: Phytochemistry, Vol. 57, No. 3, 06.2001, p. 349-359.

Research output: Contribution to journalArticle

Li, Sing Chung ; Han, Jiahn Wern ; Chen, Kuan Chung ; Chen, Ching San. / Purification and characterization of isoforms of β-galactosidases in mung bean seedlings. In: Phytochemistry. 2001 ; Vol. 57, No. 3. pp. 349-359.
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