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Characterization of Recombinant Rhamnogalacturonan α-l-Rhamnopyranosyl-(1,4)-α-d-Galactopyranosyluronide Lyase from Aspergillus aculeatus1: An Enzyme That Fragments Rhamnogalacturonan I Regions of Pectin
The four major oligomeric reaction products from saponified modified hairy regions (MHR-S) from apple, produced by recombinant rhamnogalacturonan (RG) α-l-rhamnopyranosyl-(1,4)-α-d-galactopyranosyluronide lyase (rRG-lyase) from Aspergillus aculeatus , were isolated and characterized by 1 H-nuclear m...
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Published in: | Plant physiology (Bethesda) 1998-05, Vol.117 (1), p.141-152 |
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Main Authors: | , , , , , |
Format: | Article |
Language: | English |
Online Access: | Get full text |
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Summary: | The four major oligomeric reaction
products from saponified modified hairy regions (MHR-S) from apple,
produced by recombinant rhamnogalacturonan (RG)
α-l-rhamnopyranosyl-(1,4)-α-d-galactopyranosyluronide
lyase (rRG-lyase) from
Aspergillus aculeatus
, were
isolated and characterized by
1
H-nuclear magnetic resonance
spectroscopy. They contain an alternating RG backbone with a degree of
polymerization of 4, 6, 8, and 10 and with an α-Δ-(4,5)-unsaturated
d-galactopyranosyluronic acid at the nonreducing end and an
l-rhamnopyranose at the reducing end.
l-Rhamnopyranose units are substituted at C-4 with
β-galactose. The maximum reaction rate of rRG-lyase
toward MHR-S at pH 6.0 and 31°C was 28 units mg
−1
.
rRG-lyase and RG-hydrolase cleave the same alternating RG I subunit in
MHR. Both of these enzymes fragment MHR by a multiple attack mechanism.
The catalytic efficiency of rRG-lyase for MHR increases with decreasing
degree of acetylation. Removal of arabinose side chains improves the
action of rRG-lyase toward MHR-S. In contrast, removal of galactose
side chains decreased the catalytic efficiency of rRG-lyase. Native
RG-lyase was purified from
A. aculeatus
, characterized,
and found to be similar to the rRG-lyase expressed in
Aspergillus oryzae
. |
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ISSN: | 0032-0889 1532-2548 |