Activity Change of Pectinesterase Inhibitor on Banana of Postharvested and the Mechanisms of such Pectinesterase Inhibitor on Fruit Pectinesterases
Date Issued
2005
Date
2005
Author(s)
Wu, Bo-Jhih
DOI
zh-TW
Abstract
Banana, one of important fruits in economic in Taiwan, is a very
typical climacteric fruit. It softens during ripening due to the first
pectinesterase (PE) reaction and the subsequent polygalacturonase (PG)
and cellulose actions. Many substances exhibiting PE inhibitory activity,
PE inhibitor (PEI), in fruits and vegetables have been reported. In the
present study, isolation and purification of banana PEI and its inhibition
mechanisms on PEs were conducted using affinity gel chromatographies,
ELISA, SDS-PAGE, and western blotting.
Green banana with a peel color index (PCI) 1 were divided into
low-temperature (10°C) storage group (for up to 18 days) and
low-temperature room temperature (25 ± 2 °C) storage group (for 18 days
first then 7 days at room temperature) to investigate the changes in PE
and PEI activities. In room temperature storage group, PE activity was
undetectable until on the14th day and it reached a maximum on the 16th
day. In low-temperature storage group, PE activity was not detected and
PEI activity decreased with the increasing storage days throughout the
18-day storage. PEI activity remains high during low-temperature storage
for up to 18 days, while it was almost undetectable during
room-temperature storage for the same period of time.
Total phenol content in banana changed slightly during storage so as
to be considered irrelevant to the PE activity change during ripening
process. Pectate lyase (PAL) activity was detected in ripe banana. From
which, two isozymes were isolated by high-methoxylated cross-linked
alcohol insoluble-substance (CL-AIS) affinity column.
PEI from water extract of green banana (PCI 1) by Sepharose
CN-PE affinity chromatography was determined to be a polysaccharide,
while PEI from extract of PCI 3 banana by the same chromatographic
method was one single protein band with a molecular weight is 23.2 kDa
with the aid of Western blotting analysis. It revealed that PEI in banana
was in various forms and displayed PE inhibitory activity in different
IV
ripening processes. Competitive inhibition of banana PEI on both banana
and citrus PEs were determined.
Crude PEI powder from PCI 1 green banana was diluted to be
0-100µg/mL to detect and construct the calibration curve of ELISA value
versus PEI activity to evaluate the PEI activity change during banana
ripening. Results showed that PEI activity and concentration decreased
with increasing storage period of time. Storage factors such as
temperature strongly influenced the PEI activity.
Subjects
香蕉
果膠酯
親和性層析
banana
pectinesterase
pectinesterase inhibitor
affinity chromatography
ELISA
Type
thesis
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