Profile of peroxidase isoforms influenced by spongy tissue disorder in Alphonso mango (<Emphasis Type="Italic">Mangifera indica</Emphasis> L.) fruits |
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Authors: | Machhindra T Janave |
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Institution: | (1) Food Technology Division, FIPLY, Bhabha Atomic Research Centre, Trombay, Mumbai, 400 085, India;(2) Present address: Laxmi Tower, B/101, Sector 42, Plot No. 7, Nerul (West), Navi Mumbai, 400 706, India |
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Abstract: | This paper describes the profile of peroxidase (POX) isoenzymes induced due to the natural infection of Staphylococcus xylosus in spongy Alphonso mango fruits. Very low levels of protein and POX activity was observed in non-spongy unripe fruits, and
when these fruits turned table-ripe, the levels of both the protein content and POX activity increased several fold. The spongy
fruits, however, showed further 2-fold increase in POX activity; although drastic decrease in protein content was observed.
Anionic and cationic PAGE, and isoelectric focusing (IEF), resulted in separation of various isoenzymes of POX. Both, anionic
and cationic PAGE indicated that, at unripe stage, only basic isoforms were present in trace amounts. In non-spongy ripe fruits,
increased levels of both anionic and cationic isoforms were observed after staining the gel with o-dianisidine, the POX substrate. In spongy fruits, however, an anionic PAGE showed appearance of four acidic isoforms with
relative electrophoretic mobility (REM) of 0.52, 0.73, 0.78, and 0.84 and an isoenzyme (REM 0.52), showed further activation,
as indicated by the intense dark color formation. Cationic PAGE also indicated higher levels of two basic isoforms (REM 0.56
and 0.62), in the spongy fruits. Isoelectric focusing resolved these isoenzymes in acidic, neutral, and basic isoforms. Two
acidic isoforms in the pI range of 2–3.5 were detected toward the anode region and two cationic isoforms of pI 7.8 and 8.7,
toward the cathode, giving visible indication of increased levels of these isoforms. The increased intensities of the POX
bands observed in anionic and cationic PAGE, and IEF, gave confirmatory evidence for the up regulation of anionic and cationic
isoforms in spongy fruits. These isoenzymes could have been overexpressed as a defense response of the spongy fruits against
the Staphylococcus infection. |
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