# Molecular and enzymatic characterization of flavonoid 3′-hydroxylase of malus × domestica
> Weissensteiner J.

URL kanonis: https://discover.unhas.ac.id/publications/pub_scopus_85115100068
Jurnal / Konferensi: Plants
Tahun terbit: 2021
DOI: https://doi.org/10.3390/plants10091956
ISSN: 22237747
Kuartil SJR: Q1
Citations: 9

## Authors
- Weissensteiner J.

## Abstract
<i>Malus</i> × <i>domestica</i> (apple) accumulates particularly high amounts of dihydrochalcones in various tissues, with phloridzin (phloretin 2'-<i>O</i>-glucoside) being prevalent, although small amounts of 3-hydroxyphloretin and 3-hydroxyphloridzin are also constitutively present. The latter was shown to correlate with increased disease resistance of transgenic <i>M.</i> × <i>domestica</i> plants. Two types of enzymes could be involved in 3-hydroxylation of dihydrochalcones: polyphenol oxidases or the flavonoid 3'-hydroxylase (F3'H), which catalyzes B-ring hydroxylation of flavonoids. We isolated two F3'H cDNA clones from apple leaves and tested recombinant <i>Malus</i> F3'Hs for their substrate specificity. From the two isolated cDNA clones, only <i>F3'HII</i> encoded a functionally active enzyme. In the F3'HI sequence, we identified two putatively relevant amino acids that were exchanged in comparison to that of a previously published F3'HI. Site directed mutagenesis, which exchanged an isoleucine into methionine in position 211 restored the functional activity, which is probably because it is located in an area involved in interaction with the substrate. In contrast to high activity with various flavonoid substrates, the recombinant enzymes did not accept phloretin under assay conditions, making an involvement in the dihydrochalcone biosynthesis unlikely.

## Keywords
- Flavonoid
- Enzyme
- Malus
- Biology
- Biochemistry
- Computational biology
- Botany
- Antioxidant

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Sumber: Discover Unhas — RIMS Universitas Hasanuddin.
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