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Title: CHARACTERIZATION OF B-GALACTOSIDASE ISOZYMES OF RIPENING PEPPERS

Author
item BILES, C - EAST CENTRAL UNIVERSITY
item Bruton, Benny
item Russo, Vincent
item WALL, MARISA - NEW MEXICO STATE UNIV

Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/4/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Total B-Galactosidase activity increased upon ripening of New Mexican type, bell, jalapeno, and yellow wax peppers. To a lesser extent, xylosidase and B-Glucosidase increased from the mature green stage to the turning stage of ripening, and then decreased in the red ripe stage. For the New Mexican type peppers, cation exchange chromatography indicated two prominent B-Galactosidase peaks (one basic and one acidic) and two minor peaks, depending on stage of ripeness. In mature green fruit, one large acidic B-Galactosidase peak and a smaller basic peak were observed. In red fruit, one small acidic peak was present with a large and small basic peak. Isoelectric focusing-polyacrylamide gel electrophoresis (IEF-PAGE) separated one band from mature green fruit (pI 4.6) and an additional B- Galactosidase isozyme as fruit turned from green to red (pI 8.0). The basic B-Galactosidase isozyme from red fruit extract had an apparent native-molecular weight of 51 kD. The optimum pH for B-Galactosidase activity was betweem 3 to 4.5. Stable enzyme activity was observed from 25 to 50C. Lineweaver Burke plots indicated B-Galactosidase from red chili fruit to have a Km of 1.16 mM and Vmax of 5.26, while the values for green chile B-Galactosidase were 2.11 mM and 2.63, respectively. The heavy metal ions Ag +2 and Hg+2 inhibited B-Galactosidase activity by 100% and 90%, respectively.

Technical Abstract: Ripening processes in peppers are important because of the increased demand for 'hot' (pungent) peppers and the increasing markets for 'sweet' red and green types. Several factors play a role in the ripening process, including specific enzymes that breakdown cell walls of fruit. The enzyme B-Galactosidase has been shown to play a possible role in the ripening of various fruits. B-Galactosidase from peppers was extracted from fruit types. All showed an increase of B-Galactosidase during ripening. Different molecular forms of the enzyme were observed in green and red fruit, suggesting that different genes may be stimulated upon ripening. Further characterization indicated the enzyme to be stable up to 50C, have a pH optimum from 3-4.5, and inhibited by silver and mercury ions. This characterization will be useful in future studies on ripening. If B-Galactosidase plays a role in ripening, then manipulation of this enzyme may enhance or decrease ripening, and effect storage and quality of pepper fruit.