Dataset Information

Dual role of imidazole as activator/inhibitor of sweet almond (Prunus dulcis) ?-glucosidase.

ABSTRACT: The activity of Prunus dulcis (sweet almond) ?-glucosidase at the expense of p-nitrophenyl-?-d-glucopyranoside at pH 6 was determined, both under steady-state and pre-steady-state conditions. Using crude enzyme preparations, competitive inhibition by 1-5 mM imidazole was observed under both kinetic conditions tested. However, when imidazole was added to reaction mixtures at 0.125-0.250 mM, we detected a significant enzyme activation. To further inspect this effect exerted by imidazole, ?-glucosidase was purified to homogeneity. Two enzyme isoforms were isolated, i.e. a full-length monomer, and a dimer containing a full-length and a truncated subunit. Dimeric ?-glucosidase was found to perform much better than the monomeric enzyme, independently of the kinetic conditions used to assay enzyme activity. In addition, the sensitivity towards imidazole was found to differ between the two isoforms. While monomeric enzyme was indeed found to be relatively insensitive to imidazole, dimeric ?-glucosidase was observed to be significantly activated by 0.125-0.250 mM imidazole under pre-steady-state conditions. Further, steady-state assays revealed that the addition of 0.125 mM imidazole to reaction mixtures increases the Km of dimeric enzyme from 2.3 to 6.7 mM. The activation of ?-glucosidase dimer by imidazole is proposed to be exerted via a conformational transition poising the enzyme towards proficient catalysis.

SUBMITTER: Caramia S

PROVIDER: S-EPMC5614632 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature

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Dual role of imidazole as activator/inhibitor of sweet almond (Prunus dulcis) β-glucosidase.

Caramia Sara S Gatius Angela Gala Morena AGM Dal Piaz Fabrizio F Gaja Denis D Hochkoeppler Alejandro A

Biochemistry and biophysics reports 20170324

The activity of Prunus dulcis (sweet almond) β-glucosidase at the expense of p-nitrophenyl-β-d-glucopyranoside at pH 6 was determined, both under steady-state and pre-steady-state conditions. Using crude enzyme preparations, competitive inhibition by 1-5 mM imidazole was observed under both kinetic conditions tested. However, when imidazole was added to reaction mixtures at 0.125-0.250 mM, we detected a significant enzyme activation. To further inspect this effect exerted by imidaz ...[more]

PMID: 28955741

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Project description:Background and aimsShoot characteristics differ depending on the meristem tissue that they originate from and environmental conditions during their development. This study focused on the effects of plant water status on axillary meristem fate and flowering patterns along proleptic and epicormic shoots, as well as on shoot growth rates on 'Nonpareil' almond trees (Prunus dulcis). The aims were (1) to characterize the structural differences between proleptic and epicormic shoots, (2) to determine whether water deficits modify shoot structures differently depending on shoot type, and (3) to determine whether shoot structures are related to shoot growth rates.MethodsA hidden semi-Markov model of the axillary meristem fate and number of flower buds per node was built for two shoot types growing on trees exposed to three plant water status treatments. The models segmented observed shoots into successive homogeneous zones, which were compared between treatments. Shoot growth rates were calculated from shoot extension measurements made during the growing season.Key resultsProleptic shoots had seven successive homogeneous zones while epicormic shoots had five zones. Shoot structures were associated with changes in growth rate over the season. Water deficit (1) affected the occurrence and lengths of the first zones of proleptic shoots, but only the occurrence of the third zone was reduced in epicormic shoots; (2) had a minor effect on zone flowering patterns and did not modify shoot or zone composition of axillary meristem fates; and (3) reduced growth rates, although patterns over the season were similar among treatments.ConclusionsTwo meristem types, with different latency durations, produced shoots with different growth rates and distinct structures. Differences between shoot type structure responses to water deficit appeared to reflect their ontogenetic characteristics and/or resource availability for their development. Tree water deficit appeared to stimulate a more rapid progression through ontogenetic states.

Dataset Information

Dual role of imidazole as activator/inhibitor of sweet almond (Prunus dulcis) ?-glucosidase.

Publications

Dual role of imidazole as activator/inhibitor of sweet almond (<i>Prunus dulcis</i>) β-glucosidase.

Similar Datasets

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