Isolation, characterization and significance of papaya β-galactanases to cell wall modification and fruit softening during ripening

Zainon Mohd Ali, Shu Yih Ng, Roohaida Othman, Lee Yin Goh, Hamid Lazan

Research output: Contribution to journalArticle

50 Citations (Scopus)

Abstract

β-Galactosidases (EC 3.2.1.23) from ripe papaya (Carica papaya L. cv. Eksotika) fruits having galactanase activities were fractionated by a combination of cation exchange and gel-filtration chromatography into three isoforms, viz., β-galactosidase I, II and III. The native proteins of the respective isoforms have apparent molecular masses of 67, 67 and 55 kDa, each showing one predominant polypeptide upon SDS-PAGE of about 31 and 33 kDa for β-galactosidases l and III, respectively, and of 67 kDa for β-galactosidase II. The β-galactosidase I protein, which was undetectable in immature fruits, appeared to be specifically accumulated during ripening. The β-galactosidase II protein was present in developing fruits, but its level seemed to decrease with ripening. β-Galactosidase I seemed to be an important softening enzyme; its activity increased dramatically (4- to 8-fold) to a peak early during ripening and correlated closely with differential softening as related to position in the fruit tissue. The inner mesocarp tissue was softer, and its wall pectins were modified earlier and firmness decreased more rapidly during ripening compared to the outer mesocarp tissue. β-Galactosidase II also may contribute significantly to softening because of its ability to catalyse increased solubility and depolymerization of pectins as well as through its ability to modify the alkali-soluble hemicellulose fraction of the cell wall. The physiological significance of both β-galactosidase isoforms may partly be attributed to their functional capacity as β-(l,4)-galactanases.

Original languageEnglish
Pages (from-to)105-115
Number of pages11
JournalPhysiologia Plantarum
Volume104
Issue number1
DOIs
Publication statusPublished - Sep 1998

Fingerprint

Galactosidases
Carica
galactosidases
papayas
Cell Wall
Fruit
ripening
cell walls
fruits
Pectins
Protein Isoforms
Carica papaya
mesocarp
pectins
protein isoforms
depolymerization
cation exchange
Alkalies
beta-galactosidase
hemicellulose

Keywords

  • β-galactosidase/galactanase
  • Carica papaya
  • Celt wall
  • Hemicellulose
  • Pectin
  • Ripening
  • Softening

ASJC Scopus subject areas

  • Plant Science

Cite this

Isolation, characterization and significance of papaya β-galactanases to cell wall modification and fruit softening during ripening. / Ali, Zainon Mohd; Ng, Shu Yih; Othman, Roohaida; Goh, Lee Yin; Lazan, Hamid.

In: Physiologia Plantarum, Vol. 104, No. 1, 09.1998, p. 105-115.

Research output: Contribution to journalArticle

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