• Korean Journal of Food Science and Technology
• /
• v.15 no.4
• /
• pp.404-408
• /
• 1983

Some properties of malic enzyme (EC 1.1.1.40) prepared from malate-decomposition yeast, Schizosac-charomyces japonicus var. japonicus St-3 were investigated. The activity of malic enzyme was maximum when it was cultured for 24 hours. The optimum conditions for the enzyme reaction were pH 10.0 and temperature of $25^{\circ}C$. The crude enzyme was very stable at the range of pH 7.0-8.4, and almost 50 percent of enzyme activity was lost by heating at $60^{\circ}C$ for 10 minutes. The malic enzyme activity was enhanced by the addition of $Mn^{++}$. But the enzyme activity was not affected by the addition of organic acids, amino acids and ethanol, respectively.

• Korean Journal of Food Science and Technology
• /
• v.16 no.1
• /
• pp.90-94
• /
• 1984

We deduced a possible metabolic pathway of L-malate in a malo-alcoholic yeast, Schizosaccharomyces japonicus var. japonicus St-3. The malic enzyme (EC 1.1.1.40) prepared from the microorganism was about four times as active as that of malate dehydrogenase (EC 1.1.1.37). And Km values of malic enzyme and malate dehydrogenase for malate were found to be 3.125 mM and 4.761 mM, respectively, which referred to the fact that the affinity of malic enzyme for the substrate was greater than that of malate dehydrogenase. We also found that pyruvate was produced with disappearing malate in malo-alcoholic fermentation, and that the addition of $Mn^{2+}$ activated malic enzyme activity. Based on these results obtained we have deduced a main pathway of malate${\rightarrow}$pyruvate${\rightarrow}$acetaldehyde${\rightarrow}$ethanol for the utilization of L-malate by this malo-alcoholic yeast strain.

• Journal of Microbiology and Biotechnology
• /
• v.10 no.4
• /
• pp.496-501
• /
• 2000

Escherichia cole NZN111, which is known as a pfl ldhA double mutant strin, was metabolically engineered to produce succinic acid by overexpressing malic enzyme into the E. coli controlled by a trc promoter. Fermentation studies were carried out in a LB medium by first growing cells aerobically to an $OD_{600}$ of 5. At this point, 0.01 mM IPTG was added to induce the overexpression of malic enzyme and the agitation speed was gradually lowered. When the culture $OD_{600}$ reached 11, a complete anaerobic condition was achieved by flushing with a $CO_3-H_2$ gas mixture. When NZN111(pTrcML) was cultured at $37^{\circ}C$, the final succinic acid concentration of 2.8 g/l could be obtained after 30 h of anaerobic cultivation. The fermentation results were analyzed by the calculation of metabolic fluxes. Metaolic flux analysis showed that about 85% of phosphoenolpyruvate (PEP) was converted to pyruvate, and further converted to malic acid by malic enzyme.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.9 no.4
• /
• pp.252-255
• /
• 2004

A pfl ldhA double mutant Escherichia coli strain NZN 111 was used to produce succinic acid by overexpressing the E. coli malic enzyme gene (sfcA). This strain, however, produced a large amount of malic acid as well as succinic acid. After the analyses of the metabolic pathways, the fumB gene encoding the anaerobic fumarase of E. coli was co-amplified to solve the problem of malic acid accumulation. A plasmid, pTrcMLFu, was constructed, which contains an artificial operon (sfcA-fumB) under the control of the inducible trc promoter. From the batch culture of recombinant E. coli NZN 111 harboring pTrcMLFu, 7 g/L of succinic acid was produced from 20 g/L of glucose, with no accumulation of malic acid. From the metabolic flux analysis the strain was found under reducing power limiting conditions by severe reorientation of metabolic fluxes.

• Asian-Australasian Journal of Animal Sciences
• /
• v.16 no.10
• /
• pp.1524-1528
• /
• 2003

The present study was conducted to evaluate the influence of dietary fiber on the activities of malic enzyme and citrate lyase involved in fatty acid metabolism in the colon epithelium of pigs. Thirty-six weaned 5 weeks old crossbred (Yorkshire${\times}$Swedish Landrace) piglets originating from twelve litters were randomly assigned to either a low fiber diet containing 10% non-starch polysaccharides (NSP), a control diet containing 14.7% NSP or a high fiber diet containing 20% NSP. The activity of malic enzyme in the colonic epithelium of pigs significantly (p<0.05) increased with age during the suckling-weaning transition. There was a tendency (p<0.10) of decreased malic enzyme activity in the colonic epithelium of pigs fed on the high fiber diet. At week 6, a lowered (p<0.01) activity of malic enzyme in pigs fed on the low fiber diet compared with that in pigs fed on the high fiber and the control diets. Nevertheless, there were no significant differences in the activity of citrate lyase observed either between pigs with different ages or between pigs fed with various diets. The current data suggest that piglets during the suckling-weaning transition have a limited capacity to synthesize fatty acids from carbohydrate derivatives in the coloncytes. In addition, lipogenesis in coloncytes was enhanced with age during the suckling-weaning transition. A tendency (p<0.10) to an increased capacity to utilize acetyl-CoA in coloncytes of pigs has been observed for the high fiber diet. Moreover, the present work indicated that dietary fiber resulted in a lowered rate of lipogenesis and a reduced activity of malic enzyme.

• Preventive Nutrition and Food Science
• /
• v.4 no.1
• /
• pp.79-83
• /
• 1999

A potentiometric biosensor employing a CO3-2 ion-selective electrode(ISE) and malic enzyme immobilization in al flow injection analysis (FIA) system was constructed. Analytical parameters were optimized for L-malate determination . The CO3-2 -ISE-FIA system was composed of a pump, an injector, a malic enzyme (EC1.1.1.40) reactor, a CO3-2 ion-selective electrode, a pH/mV meter and a recorder. Cofactor NADP was also injected with substrate for theenzyme reaction into the system. Optimized analytical parameters for L-malate determination in the CO3-2 ISE-FIA system were as follows ; flow rate, 14.5ml/hr ; sample injection volume, 100ul; enzyme loading in the reactor, 20 units ; length of the enzyme reactor , 7 cm ; tubing length form the enzyme reactor to the detector as a geometric factor in FIA, 15 cm . The response time for measuring the entire L-malate concentration range (10-2 ~10-5 mol/L ; 4 injections )was <15minutes . In this CO3-2 -ISE-FIA system, the potential differences due to th eformation of CO3-2 by the reaction of malic enzyme on L-malate were correlated to L-malate concentration in the range of 10-2 ~10-5mol/L ; the detection limit was 10-5 mol/L. This potentionmetric CO3-2 ISE--FIA system was found to be useful for L-malate measurement.

• Food Science and Preservation
• /
• v.18 no.5
• /
• pp.795-802
• /
• 2011

To determine the deacidification factor during carbonic maceration (CM), different temperature conditions were studied. The pH was higher in CM-$35^{\circ}C$ and CM-$25^{\circ}C$ and was lower in CM-$45^{\circ}C$. The total acid was inversely related to the pH. The malic-acid level decreased much more in CM-$35^{\circ}C$ than in CM-$45^{\circ}C$ while the lactic-acid level increased much more in CM-$35^{\circ}C$. The activity of the NADP-malic enzyme, which catalyzes the oxidative decarboxylation of L-malate into pyruvate, $CO_2$, and NADPH, was higher in CM-$25^{\circ}C$ and CM-$35^{\circ}C$ while CM-$45^{\circ}C$ showed no NADP-malic enzyme activity. The malic-dehydrogenase (MDH) activity was higher in CM-$25^{\circ}C$ and CM-$35^{\circ}C$ while CM-$45^{\circ}C$ showed no MDH activity. The oxalacetate decarboxylase activity was similar to the NADP-malic-enzyme and MDH activities. Pyruvate decarboxylase activity was shown in all the CM treatments. The L-lactic dehydrogenase (LDH) activity was not explored in the fermentation of pyruvate to lactate via LDH in the grapes during CM. In this study, it was confirmed that carbonic maceration reduced the malic acid during fermentation and was affected by the temperature. Moreover, it was assumed that the deacidification during the carbonic maceration of the grapes was probably correlated with the degradation enzyme activity of malic acid.

• Journal of Microbiology and Biotechnology
• /
• v.17 no.9
• /
• pp.1579-1584
• /
• 2007

5-Aminolevulinate (ALA) synthase (E.C. 2.3.1.37), which mediates the pyridoxal phosphate-dependent condensation of glycine and succinyl-CoA, encoded by the Rhodobacter sphaeroides hemA gene, enables Escherichia coli strains to produce ALA at a low level. To study the effect of the enhanced C4 metabolism of E. coli on ALA biosynthesis, NADP-dependent malic enzyme (maeB, E.C. 1.1.1.40) was coexpressed with ALA synthase in E. coli. The concentration of ALA was two times greater in cells coexpressing maeB and hemA than in cells expressing hemA alone under anaerobic conditions with medium containing glucose and glycine. Enhanced ALA synthase activity via coupled expression of hemA and maeB may lead to metabolic engineering of E. coli capable of large-scale ALA production.

• Korean Journal of Weed Science
• /
• v.8 no.2
• /
• pp.133-140
• /
• 1988

One hundred and one noxious weeds on cultivated land of Taiwan were investigated for the occurrence of "Kranz" leaf anatomy and activities of PEP carboxylase and $C_4$ acid decarboxylating enzymes : NADP-malic enzyme, NAD-malic enzyme, PEP carboxykinase. Based on the leaf anatomy and a/b chlorophyll ratio, twenty-seven species exhibit "Kranz" type leaf anatomy, and seventy-four species were found without it. Among the species investigated, Digitaria radicosa (Presl) Miq., Leptochloa chinensis (L.) Nees, and Sporobolus fertilis (Steud.) W. D. Clayton in the Gramineae were first recorded as $C_4$ plants. Twenty-sven species of "Kranz" type leaf anatomy, include those of monocotyledon ; sixteen species in Gramineae, six species in Cyperaceae. Those of dicotyledon ; two species each in Euphorbiaceae and Amaranthaceae and one species in Portulacaceae. The subtype of fourteen previously uninvestigated species among twenty-seven species were further determined. The properties of the three decarboxylating enzyme from representative species were also characterized.

• Parasites, Hosts and Diseases
• /
• v.44 no.4 s.140
• /
• pp.373-378
• /
• 2006

To evaluate whether iron concentration in TYM medium influence on hydrogenosomal enzyme gene expression and hydrogenosomal membrane potential of Trichomonas vaginalis, trophozoites were cultivated in iron-depleted, normal and iron-supplemented TYM media. The mRNA of hydrogenosomal enzymes, such as pyruvate ferredoxin oxidoreductase (PFOR), hydrogenase, ferredoxin and malic enzyme, was increased with iron concentrations in T. vaginalis culture media, measured by RT-PCR. Hydrogenosomal membrane potentials measured with $DiOC_6$ also showed similar tendency, e.g. T. vaginalis cultivated in iron-depleted and iron-supplemented media for 3 days showed a significantly reduced and enhanced hydrogenosomal membrane potential compared with that of normal TYM media, respectively. Therefore, it is suggested that iron may regulate hydrogenosomal activity through hydrogenosomal enzyme expression and hydrogenosomal membrane potential.