The physiological role of malic enzyme in grape ripening

Planta ◽  
1984 ◽  
Vol 160 (5) ◽  
pp. 444-448 ◽  
Author(s):  
H. P. Ruffner ◽  
D. Possner ◽  
S. Brem ◽  
D. M. Rast
Keyword(s):  
Malic Enzyme ◽  
Physiological Role

scholarly journals YtsJ Has the Major Physiological Role of the Four Paralogous Malic Enzyme Isoforms in Bacillus subtilis

2006 ◽  
Vol 188 (13) ◽  
pp. 4727-4736 ◽  
Author(s):  
Guillaume Lerondel ◽  
Thierry Doan ◽  
Nicola Zamboni ◽  
Uwe Sauer ◽  
Stéphane Aymerich
Keyword(s):  
Enzyme Activity ◽  
Bacillus Subtilis ◽  
Malic Enzyme ◽  
Metabolic Flux ◽  
Physiological Role ◽  
Extreme Case ◽  
Growth Defect ◽  
Flux Analysis ◽  
Malic Enzyme Activity

ABSTRACT The Bacillus subtilis genome contains several sets of paralogs. An extreme case is the four putative malic enzyme genes maeA, malS, ytsJ, and mleA. maeA was demonstrated to encode malic enzyme activity, to be inducible by malate, but also to be dispensable for growth on malate. We report systematic experiments to test whether these four genes ensure backup or cover different functions. Analysis of single- and multiple-mutant strains demonstrated that ytsJ has a major physiological role in malate utilization for which none of the other three genes could compensate. In contrast, maeA, malS, and mleA had distinct roles in malate utilization for which they could compensate one another. The four proteins exhibited malic enzyme activity; MalS, MleA, and MaeA exhibited 4- to 90-fold higher activities with NAD+ than with NADP+. YtsJ activity, in contrast, was 70-fold higher with NADP+ than with NAD+, with Km values of 0.055 and 2.8 mM, respectively. lacZ fusions revealed strong transcription of ytsJ, twofold higher in malate than in glucose medium, but weak transcription of malS and mleA. In contrast, mleA was strongly transcribed in complex medium. Metabolic flux analysis confirmed the major role of YtsJ in malate-to-pyruvate interconversion. While overexpression of the NADP-dependent Escherichia coli malic enzyme MaeB did not suppress the growth defect of a ytsJ mutant on malate, overexpression of the transhydrogenase UdhA from E. coli partially suppressed it. These results suggest an additional physiological role of YtsJ beyond that of malate-to-pyruvate conversion.

scholarly journals Cloning of the Malic Enzyme Gene fromCorynebacterium glutamicum and Role of the Enzyme in Lactate Metabolism

2000 ◽  
Vol 66 (7) ◽  
pp. 2981-2987 ◽  
Author(s):  
Pierre Gourdon ◽  
Marie-France Baucher ◽  
Nic D. Lindley ◽  
Armel Guyonvarch
Keyword(s):  
Exponential Growth ◽  
Malic Enzyme ◽  
Tricarboxylic Acid Cycle ◽  
Physiological Role ◽  
Growth Period ◽  
Biochemical Properties ◽  
Lactate Metabolism ◽  
Wild Type ◽  
Malic Enzyme Gene

ABSTRACT Malic enzyme is one of at least five enzymes, known to be present in Corynebacterium glutamicum, capable of carboxylation and decarboxylation reactions coupling glycolysis and the tricarboxylic acid cycle. To date, no information is available concerning the physiological role of the malic enzyme in this bacterium. ThemalE gene from C. glutamicum has been cloned and sequenced. The protein encoded by this gene has been purified to homogeneity, and the biochemical properties have been established. Biochemical characteristics indicate a decarboxylation role linked to NADPH generation. Strains of C. glutamicum in which themalE gene had been disrupted or overexpressed showed no detectable phenotype during growth on either acetate or glucose, but showed a significant modification of growth behavior during lactate metabolism. The wild type showed a characteristic brief period of exponential growth on lactate followed by a linear growth period. This growth pattern was further accentuated in a malE-disrupted strain (ΔmalE). However, the strain overexpressingmalE maintained exponential growth until all lactate had been consumed. This strain accumulated significantly larger amounts of pyruvate in the medium than the other strains.

Physiological Role of Malic Enzyme in Liver

1968 ◽  
Vol 63 (6) ◽  
pp. 805-807 ◽  
Author(s):  
FUMIO WADA ◽  
ETSUKO MARUYAMA ◽  
KIYOKO SHIBAYAMA ◽  
YUKIYA SAKAMOTO
Keyword(s):  
Malic Enzyme ◽  
Physiological Role

Dark CO2 fixation by cell-free preparations of the wood of Robinia pseudoacacia

1974 ◽  
Vol 52 (4) ◽  
pp. 727-734 ◽  
Author(s):  
Wolfgang Höll
Keyword(s):  
Organic Compounds ◽  
Malic Enzyme ◽  
Co2 Fixation ◽  
Robinia Pseudoacacia ◽  
Physiological Role ◽  
Annual Rings ◽  
Ph Optimum ◽  
Robinia Pseudoacacia L ◽  
Dark Co2 Fixation

In the presence of phosphoenolpyruvate, cell-free preparations from distinct annual ring tissues of the trunk and the root of Robinia pseudoacacia L. incorporate 14CO2 into organic compounds. The CO2 fixation process exhibits a pH optimum at 7.8 and is activated by Mg2+. Aspartic acid contained 97% of the radioactivity incorporated. Oligosaccharides, malic acid, fumaric acid, glutamic acid, and three substances not identified with certainty show minor labeling. The activities of malate dehydrogenase (EC. 1.1.1.37), aspartate aminotransferase (EC. 2.6.1.1), and "malic enzyme" (EC. 1.1.1.40), involved in the further metabolism of the primary CO2 fixation product oxaloacetate, were detected spectrophotometrically in preparations from different annual rings of the trunk. Compared with the outer zones, the innermost part of the sapwood shows only little activity of these enzymes. The capacity to transfer CO2 into organic compounds decreases in the radial direction of both trunk and root wood. Heartwood preparations exhibit no CO2 fixation. In comparison to the trunk, the wood of the root shows only little dark CO2 fixation. The possible physiological role of this nonautotrophic CO2 binding in the wood of Robinia is discussed.

Physiological Role of Cyclic Electron Flow in Higher Plants

2012 ◽  
Vol 30 (1) ◽  
pp. 100
Author(s):  
Wei HUANG ◽  
Shi-Bao ZHANG ◽  
Kun-Fang CAO
Keyword(s):  
Higher Plants ◽  
Electron Flow ◽  
Physiological Role ◽  
Cyclic Electron Flow

The Renal Outer Medullary Potassium Channel (ROMK): An Intriguing Pharmacological Target for an Innovative Class of Diuretic Drugs

2018 ◽  
Vol 25 (23) ◽  
pp. 2627-2636 ◽  
Author(s):  
Vincenzo Calderone ◽  
Alma Martelli ◽  
Eugenia Piragine ◽  
Valentina Citi ◽  
Lara Testai ◽  
...  
Keyword(s):  
Physiological Role ◽  
Clinical Use ◽  
Diuretic Activity ◽  
First Line ◽  
Potassium Homeostasis ◽  
Diuretic Drugs ◽  
Pharmacological Target ◽  
Diuretic Agents ◽  
Effective Drugs

In the last four decades, the several classes of diuretics, currently available for clinical use, have been the first line option for the therapy of widespread cardiovascular and non-cardiovascular diseases. Diuretic drugs generally exhibit an overall favourable risk/benefit balance. However, they are not devoid of side effects. In particular, all the classes of diuretics cause alteration of potassium homeostasis. <p> In recent years, understanding of the physiological role of the renal outer medullary potassium (ROMK) channels, has shown an intriguing pharmacological target for developing an innovative class of diuretic agents: the ROMK inhibitors. This novel class is expected to promote diuretic activity comparable to (or even higher than) that provided by the most effective drugs used in clinics (such as furosemide), with limited effects on potassium homeostasis. <p> In this review, the physio-pharmacological roles of ROMK channels in the renal function are reported, along with the most representative molecules which have been currently developed as ROMK inhibitors.

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