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Digitale Medien

Tricarboxylic acid and glyoxylate cycle enzyme activities in Thiobacillus versutus, an isocitrate lyase negative organism (1986)

Claassen, Pieternel A. M. ; Kortstee, Gerard J. J. ; Dijken, Johannes P. ; [weitere]

Springer

Archives of microbiology 145 (1986), S. 148-152

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ISSN: 1432-072X

Schlagwort(e): TCA and glyoxylate cycle enzymes ; Acetate metabolism ; Isocitrate lyase negative ; Thiobacillus versutus

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract An analysis was made of the specific enzyme activities of the TCA and glyoxylate cycle in Thiobacillus versutus cells grown in a thiosulphate- or acetate-limited chemostat. Activities of all enzymes of the TCA cycle were detected, irrespective of the growth substrate and they were invariably lower in the thiosulphate-grown cells. Of the glyoxylate cycle enzymes, isocitrate lyase was absent but malate synthase activity was increased from 15 nmol·min-1·mg-1 protein in thiosulphate-grown cells to 58 nmol·min-1·mg-1 protein in acetate-grown cells. Suspensions of cells grown on thiosulphate were able to oxidize acetate, although the rate was 3 times lower than that observed with acetate-grown cells. The respiration of acetate was completely inhibited by 10 mM fluoroacetate or 5 mM arsenite. Partially purified citrate synthase from both thiosulphate- and acetate-grown cells was completely inhibited by 0.5 mM NADH and was insensitive to inhibition by 1 mM 2-oxoglutarate or 1 mM ATP. The specific enzyme activities of the TCA and glyoxylate cycle in T. versutus were compared with those of Pseudomonas fluorescens, an isocitrate lyase positive organism, after growth in a chemostat limited by acetate, glutarate, succinate or glutamate. The response of the various enzyme activities to a change in substrate was similar in both organisms, with the exception of isocitrate lyase.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00446772

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Digitale Medien

Increase in phosphorylase activity during cold-induced sugar accumulation in potato tubers (1993)

Claassen, Pieternel A. M. ; Budde, Miriam A. W. ; Calker, Martha H.

Springer

Potato research 36 (1993), S. 205-217

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ISSN: 1871-4528

Schlagwort(e): Solanum tuberosum ; glycolytic enzymes ; glucose 6-phosphate

Quelle: Springer Online Journal Archives 1860-2000

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft

Notizen: Summary The accumulation of reducing sugars, sucrose and hexose phosphates in cv. Bintje and genotype KW77-2916 during storage at 2, 4, or 8°C was studied in relation to several catalytic activities. Bintje tubers accumulated sugars during storage at 2 or 4°C, whereas KW77-2916 showed reduced cold-sweetening at 2°C. The increase in glucose 6-phosphate and sucrose occurred concurrently and preceded the increase in reducing sugar concentration. Phosphorylase activity showed a strong interaction with temperature, storage duration and sugar accumulation in both genotypes. Invertase activity increased in Bintje concomitantly with the increase in reducing sugars, but this effect was less obvious in KW77-2916. The activities of other glycolytic and Krebs cycle enzymes showed no obvious correlation with sugar accumulation. It is suggested that the increase in phosphorylase activity acts as a triggering event in the sweetening of potato tubers during cold storage.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02360529

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Digitale Medien

Possible involvement of fructose 1,6-bisphosphatase in cold-induced sweetening of potato tubers (1996)

Claassen, Pieternel A. M. ; Budde, Miriam A. W.

Springer

Potato research 39 (1996), S. 141-151

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ISSN: 1871-4528

Schlagwort(e): FBPase ; PFP ; Solanum tuberosum L. ; low temperature storage ; sugars

Quelle: Springer Online Journal Archives 1860-2000

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft

Notizen: Summary In measuring fructose 1,6-bisphosphatase (EC 3.1.3.11; FBPase) in potato tubers, we used anti PFP antibodies to ensure that the assay was specific for FBPase and that PPi:fructose 6-phosphate 1-phosphotransferase (EC 2.7.1.90: PFP) did not contribute to the production of fructose 6-phosphate (Fru-6-P). The involvement of cytosolic FBPase in cold sweetening was determined by monitoring enzyme activity during storage ofSolanum tuberosum cv. Erntestolz tubers at 2 or 8°C. In contrast to the rapid increase in sucrose and reducing sugars, the specific activity of FBPase showed no change and PFP rose slightly during storage at 2°C. Sugar concentrations and enzyme activities remained virtually unchanged during storage at 8°C. These data allow the interconversion of fructose 1.6-bisphosphate (Fru-1,6-P2) to Fru-6-P and vice versa by FBPase and PFP, respectively, in potato tubers, but do not support a causal relationship between coarse metabolic control of FBPase and cold-induced sweetening.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02358214

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