Insights into the functional architecture of the catalytic center of a maize beta-glucosidase Zm-p60.1

Kód výsledku v IS VaVaI

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Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Insights into the functional architecture of the catalytic center of a maize beta-glucosidase Zm-p60.1

Popis výsledku v původním jazyce

The maize beta-glucosidase Zm-p60.1 has been implicated in regulation of plant development by the targeted release of free cytokinins from cytokinin-O-glucosides, their inactive storage forms. The crystal structure of the enzyme indicated that the enzymespecificity toward substrates with aryl aglycones is determined by aglycone aromatic system stacking with W373, and interactions with edges of F193, F200 and F461 located opposite W373 in a slot-like aglycone-binding site. Recently, these aglycone-active-site interactions were hypothesized to determine substrate specificity in inactive enzyme-substrate complexes of ZMGlu1, an allozyme of Zm-p60.1. We tested this hypothesis by kinetic analysis of F193I/Y/W mutants. The decreased Km of all mutants confirmed the involvement of F193 in determining enzyme affinity towards substrates with an aromatic aglycone. Unexpectedly, a 30-fold decrease in kcat was found in F193I mutant compared to the wild type. Kinetic analysis and computer modeling

Název v anglickém jazyce

Insights into the functional architecture of the catalytic center of a maize beta-glucosidase Zm-p60.1

Popis výsledku anglicky

The maize beta-glucosidase Zm-p60.1 has been implicated in regulation of plant development by the targeted release of free cytokinins from cytokinin-O-glucosides, their inactive storage forms. The crystal structure of the enzyme indicated that the enzymespecificity toward substrates with aryl aglycones is determined by aglycone aromatic system stacking with W373, and interactions with edges of F193, F200 and F461 located opposite W373 in a slot-like aglycone-binding site. Recently, these aglycone-active-site interactions were hypothesized to determine substrate specificity in inactive enzyme-substrate complexes of ZMGlu1, an allozyme of Zm-p60.1. We tested this hypothesis by kinetic analysis of F193I/Y/W mutants. The decreased Km of all mutants confirmed the involvement of F193 in determining enzyme affinity towards substrates with an aromatic aglycone. Unexpectedly, a 30-fold decrease in kcat was found in F193I mutant compared to the wild type. Kinetic analysis and computer modeling

Druh

D - Stať ve sborníku

CEP obor

CE - Biochemie

OECD FORD obor

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Projekt

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Návaznosti

Z - Vyzkumny zamer (s odkazem do CEZ)

Rok uplatnění

2002

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

IUCr. XIX Congress - Abstracts, Volume I

ISBN

ISSN: 0108-7673

ISSN

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e-ISSN

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Počet stran výsledku

1

Strana od-do

"C106"

Název nakladatele

IUCr.

Místo vydání

Geneva

Místo konání akce

August 6-15, 2002, Geneva, Switzerland

Datum konání akce

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Typ akce podle státní příslušnosti

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Kód UT WoS článku

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