Search results for "Fructose"

Properties of locust muscle 6-phosphofructokinase and their importance in the regulation of glycolytic flux during prolonged flight

1987

6-Phosphofructokinase (PFK, EC 2.7.1.11) from the flight muscle of the locust (Locusta migratoria) was purified to a specific activity of 80 μmol min−1 (mg protein)−1 (at 25°C). 1. The enzyme is made up from subunits ofMr-81600, and the smallest catalytically active form is likely to be a tetramer. 2. PFK activity is markedly affected by the pH of the assay; the optimum pH was at about 8. 3. Physiological concentrations of ATP strongly inhibit locust PFK by shifting the S0.5 for fructose 6-phosphate (concentration required for 50% of maximum activity) out of the physiological concentration range. At pH 7.4 and about physiological concentrations of ATP, the curve of PFK activity against the …

Effect of season and soil treatments on carbohydrate concentrations in Norway spruce (Picea abies) mycorrhizae

1998

We studied effects of season and soil treatments (watering, acidification, liming and combinations of these treatments) on soluble carbohydrates of mycorrhizal roots of Norway spruce (Picea abies (L.) Karst.). Arabinose, arabitol, fructose, glucose, inositol, lactose, mannitol, pinite, quinate, raffinose, shikimate, stachyose and trehalose were identified by HPLC. Concentrations of inositol, lactose and pinite were constant throughout the year, whereas concentrations of raffinose, stachyose and trehalose were higher in winter than in summer, and concentrations of glucose, fructose and mannitol increased from February to September. Soil acidification and liming had no effect on the annual me…

Stabilization of immobilized cell systems using a modified metal surface, fructose polymer levan and a high cell concentration

1998

High efficiency joint CZE determination of sugars and acids in vegetables and fruits

2012

In this work, an improved CE method for the medium-throughput determination of main organic acids (oxalate, malate, citrate), the amino acid glutamate and the sugars fructose, glucose and sucrose in several food matrices is described. These compounds have been identified as key components in the taste intensity of fruit and vegetable crops. Using a running buffer with 20 mM 2,6-pyridine dicarboxylic acid pH 12.1 and 0.1% hexadimethrine bromide, replacing it every 5 h to avoid pH decrease, and optimizing capillary conditioning between runs with 58 mM SDS during 2 min at 20 psi, it is possible to effectively quantify these compounds while increasing medium throughput repeatability. This proce…

Chemoenzymatische „Chiral-Pool”-Synthese von (+)-exo-Brevicomin aus Kohlenhydraten mit Fructose-1,6-diphosphat-Aldolase

1990

Chemoenzymatic “Chiral-Pool” Synthesis of (+)-exo-Brevicomin from Carbohydrates Using Fructose 1,6-Diphosphate Aldolase Fructose-1,6-diphosphate aldolase (EC 4.1.2.13) catalyzes the stereospecific aldol reaction between 1,3-dihydroxyacetone phosphate (4) and 5-oxohexanal (3) or its 5-dithiane-protected analog 8. The products of the aldol reactions are dephosphorylated with acid phosphatase (EC 3.1.3.2). Whereas the aldol adduct of 3 cyclizes spontaneously to give the bicyclic brevicomin precursor 3, the adduct of 8 first has to be deprotected with sulfuryl chloride and wet silica gel. The resulting bicyclic α-hydroxy ketone 3 is reduced with LiAlH4 to form the 1,2-diol 14 which is then deox…

Stereospecific CC-bond formation with rabbit muscle aldolase - A chemoenzymatic synthesis of (+)-exo-brevicomin

1990

Abstract (+)-(1S,5R,7S)-Exo-brevicomin 9, a sex pheromone of the western pine bark beetle, is synthesized using an aldol reaction catalyzed by fructose-1,6-diphosphate aldolase (EC 4.1.2.13) from rabbit muscle as the key step by which the absolute configuration of the target is established.

Biotechnological characterisation of exocellular proteases produced by enologicalHanseniasporaisolates

2014

Summary Twenty-six enological Hanseniaspora isolates were identified by ITS PCR-RFLP and D1/D2 domain of 26S rDNA sequencing and assayed for exocellular protease production. Based on qualitative data, six isolates, belonging to H. guilliermondii, H. valbyensis and H. occidentalis species, were selected to continue the study. Analytical procedure was optimised, and protease activities were quantified and characterised on the basis of different biotechnological factors. Protease activity was quite glucose, fructose and ethanol content independent, but divalent cation affects activity; these data support that they were aspartic proteases. The effect of 2-mercaptoethanol suggests the importance…

Differential function of the phosphoglucomutase isozymes PGM1 and PGM2

1979

A total of 13 metabolites thought to be possibly inhibitory were tested for their influence on PGM isozyme activities, each at several different concentrations. The analysis of statistical significance was based on enzyme activities obtained by densitometric measurements of starch gels. Five of the substances were found to inhibit PGM activity, three of which definitely and a further one probably led to a significantly stronger inhibition of the isozymes of the PGM2 locus than of PGM1 isozymes. They are (1) fructose-1,6-diphosphate, (2) adenosine triphosphate, (3) citrate, and (4) possibly 2,3-diphosphoglycerate. Thus, PGM1 isozymes proved to function better in hard or perhaps marginal meta…

Bioactivation of the Fungal Phytotoxin 2,5-Anhydro-D-glucitol by Glycolytic Enzymesisan Essential Component of itsMechanism of Action

2002

An isolate of Fusarium solani, NRRL 18883, produces the natural phytotoxin 2,5-anhydro-ᴅ-glucitol (AhG). This fungal metabolite inhibited the growth of roots (I50 of 1.6 mᴍ), butit did nothave any in vitro inhibitory activity. The mechanism of action of AhG requires enzymatic phosphorylation by plant glycolytic kinases to yield AhG-1,6-bisphosphate (AhG-1,6- bisP), an inhibitor of Fru-1,6-bisP aldolase. AhG-1,6-bisP had an I50 value of 570 μᴍ on aldolase activity, and it competed with Fru-1,6-bisP for the catalytic site on the enzyme, with a Ki value of 103 μᴍ. The hydroxyl group on the anomeric carbon of Fru-1,6-bisP is required for the formation of an essential covalent bond to ζ amino fu…

Syntrophy of Crypthecodinium cohnii and immobilized Zymomonas mobilis for docosahexaenoic acid production from sucrose-containing substrates

2021

Marine heterotrophic dinoflagellate Crypthecodinium cohnii is an aerobic oleaginous microorganism that accumulates intracellular lipid with high content of 4,7,10,13,16,19-docosahexaenoic acid (DHA), a polyunsaturated ω-3 (22:6) fatty acid with multiple health benefits. C. cohnii can grow on glucose and ethanol, but not on sucrose or fructose. For conversion of sucrose-containing renewables to C. cohnii DHA, we investigated a syntrophic process, involving immobilized cells of ethanologenic bacterium Zymomonas mobilis for fermenting sucrose to ethanol. The non-respiring, NADH dehydrogenase-deficient Z. mobilis strain Zm6-ndh, with high ethanol yield both under anaerobic and aerobic condition…