Calorimetric investigations of the enzyme catalyzed sucrose hydrolysis

Abstract Plant roots depend on sucrose imported from leaves as the substrate for metabolism and growth. Sucrose and hexoses derived from it are also signalling molecules that modulate growth and development, but the importance for signalling of endogenous changes in sugar levels is poorly understood. We report that reduced activity of cytosolic invertase, which converts sucrose to hexoses, leads to pronounced metabolic, growth and developmental defects in roots of Arabidopsis (Arabidopsis thaliana) seedlings. In addition to altered sugar and downstream metabolite levels, roots of cinv1 cinv2 mutants have reduced elongation rates, cell and meristem size, abnormal meristematic cell division patterns, and altered expression of thousands of genes of diverse functions. Provision of exogenous glucose to mutant roots repairs relatively few of the defects. The extensive transcriptional differences between mutant and wild-type roots have hallmarks of both high sucrose and low hexose signalling. We conclude that the mutant phenotype reflects both low carbon availability for metabolism and growth and complex sugar signals derived from elevated sucrose and depressed hexose levels in the cytosol of mutant roots. Such reciprocal changes in endogenous sucrose and hexose levels potentially provide rich information about sugar status that translates into flexible adjustments of growth and development.

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Calorimetric investigations on As-Te-Se and Ge-As-Se glasses

Bulletin of Materials Science ◽

10.1007/bf02745174 ◽

1994 ◽

Vol 17 (3) ◽

pp. 225-233

Author(s):

K. Nandakumar ◽

J. Philip

Keyword(s):

Calorimetric Investigations

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Kinetics and Thermodynamics of Sucrose Hydrolysis from Real-Time Enthalpy and Heat Capacity Measurements

The Journal of Physical Chemistry B ◽

10.1021/jp067061p ◽

2007 ◽

Vol 111 (3) ◽

pp. 496-501 ◽

Cited By ~ 20

Author(s):

E. Tombari ◽

G. Salvetti ◽

C. Ferrari ◽

G. P. Johari

Keyword(s):

Heat Capacity ◽

Real Time ◽

Sucrose Hydrolysis ◽

Kinetics And Thermodynamics ◽

Heat Capacity Measurements

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CALORIMETRIC INVESTIGATIONS OF LIQUID SOLUTIONS OF THE ALKALINE EARTH NITRATES IN THE ALKALI NITRATES

The Journal of Physical Chemistry ◽

10.1021/j100815a025 ◽

1962 ◽

Vol 66 (9) ◽

pp. 1668-1671 ◽

Cited By ~ 10

Author(s):

O. J. Kleppa

Keyword(s):

Alkaline Earth ◽

Liquid Solutions ◽

Calorimetric Investigations

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Calorimetric Investigations of Organic Reactions. IV. The Heats of Ionization of dl-Alanine at 25°

Journal of the American Chemical Society ◽

10.1021/ja01256a008 ◽

1942 ◽

Vol 64 (4) ◽

pp. 762-768 ◽

Cited By ~ 11

Author(s):

Julian M. Sturtevant

Keyword(s):

Organic Reactions ◽

Calorimetric Investigations

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Inverted sugar syrup attained from sucrose hydrolysis using a membrane reactor

Brazilian Journal of Pharmaceutical Sciences ◽

10.1590/s1984-82502010000300022 ◽

2010 ◽

Vol 46 (3) ◽

pp. 571-577 ◽

Cited By ~ 5

Author(s):

Ester Junko Tomotani ◽

Michele Vitolo

Keyword(s):

Membrane Reactor ◽

Feeding Rate ◽

Sucrose Solution ◽

Sucrose Concentration ◽

Sucrose Hydrolysis ◽

Variable Parameters ◽

Sugar Syrup ◽

State Duration ◽

Styrene Divinylbenzene ◽

A Cell

Invertase, whether adsorbed on styrene-divinylbenzene copolymers or otherwise, was used for continuous sucrose hydrolysis using a cell-type membrane reactor (CTMR), coupled with an ultra (UF-100kDa), or a microfiltration (MF- pore diameter of 5 µm) membrane. In all tests, the pH (5.5), temperature (30 ºC), reaction volume (10 mL) and agitation (100 rpm) were set constant; whereas, variable parameters were: feeding rate (0.4, 0.8 and 1.6 h-1), inlet sucrose concentration (2.5, 6.5, 50 and 100 mM) and enzyme/resin ratio (1.64 mg or 3.28 mg of protein per 25, 50 or 100 mg of resin). The best result (yield of 100%, steady-state duration over 20h and specific reaction rate over 243 x 10-3 mmol/h.mE) was obtained when insoluble invertase (1.64 mg protein/100 mg resin) was used to convert 50 mM or 100 mM of sucrose solution at 0.4 h-1 using a UF-CTMR.

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