Temperature-sensitive glucose fermentation in the obligately psychrophilic yeast Candida gelida

1968 ◽  
Vol 14 (10) ◽  
pp. 1105-1110 ◽  
Author(s):  
D. W. Grant ◽  
N. A. Sinclair ◽  
C. H. Nash
Keyword(s):  
Alcoholic Fermentation ◽  
Thermal Inactivation ◽  
Pyruvate Decarboxylase ◽  
Kinetic Studies ◽  
Temperature Sensitive ◽  
Resting Cells ◽  
Enzyme Kinetic ◽  
Glucose Fermentation ◽  
Psychrophilic Yeast ◽  
Fermentative Activity

Fermentation of glucose by resting cells and cell-free extracts of the obligate psychrophile Candida gelida was essentially abolished after being heated for 30 minutes at 35 C. A survey of the enzymes of the yeast alcoholic fermentation pathway revealed that pyruvate decarboxylase was the only temperature-sensitive enzyme. Kinetic studies of thermal inactivation showed that C. gelida pyruvate decarboxylase was 50% inactivated after it was heated for 10 minutes at 35 C. Restoration of glucose fermentation rate in heated extracts from C. gelida, after addition of purified yeast pyruvate decarboxylase, confirmed that heat-induced loss of fermentative activity was due to inactivation of a temperature-sensitive pyruvate decarboxylase.

Thermolability of protein synthesis in a cell-free system from the obligately psychrophilic yeast Candida gelida

1969 ◽  
Vol 15 (4) ◽  
pp. 339-343 ◽  
Author(s):  
C. H. Nash ◽  
D. W. Grant ◽  
N. A. Sinclair
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Thermal Inactivation ◽  
Kinetic Studies ◽  
Temperature Sensitive ◽  
Free System ◽  
Psychrophilic Yeast ◽  
A Cell ◽  
Polypeptide Chains ◽  
Soluble Enzymes

A subcellular amino-acid-incorporating system from the obligately psychrophilic yeast, Candida gelida, was completely inhibited after incubation at 35 C for 30 minutes. The thermal inactivation of protein synthesis was due, in part, to the presence of unusually temperature-sensitive aminoacyl-sRNA synthetases in C. gelida extracts. Of the 13 specific synthetases examined, 7 retained less than 50% of their activity after being held at 35 C for 30 minutes. Kinetic studies of thermal inactivation of leucyl-sRNA synthetase demonstrated that this enzyme is 50% inactivated after only 7 minutes at 35 C. None of the 10 sRNA species tested was temperature sensitive. In addition to temperature-sensitive synthetases, C. gelida possesses thermolabile soluble enzymes involved in the formation of ribosomal-bound polypeptide chains.

Cellular Regulation of the Metabolism of Androgens in Rat Oral Mucosa. III. Activation of Δ4-3-ketosteroid-5α-A Ring Reductase Enzyme System by 5,5-Diphenylhydantoin

1979 ◽  
Vol 58 (2) ◽  
pp. 642-645 ◽  
Author(s):  
Jozef Vittek ◽  
Gary G. Gordon ◽  
Sydney C. Rappaport ◽  
A. Louis Southren
Keyword(s):  
Oral Mucosa ◽  
Enzyme System ◽  
Kinetic Studies ◽  
In Vitro Assay ◽  
Enzyme Kinetic ◽  
Cellular Regulation ◽  
Vitro Assay ◽  
Allosteric Mechanism

Systemic pretreatment of rats with diphenylhydantoin (DPH) or its addition into an in vitro assay increases 5α-reduction of testosterone by the oral mucosa. Enzyme kinetic studies showed that DPH binds to the enzyme and probably activates it by an allosteric mechanism.

scholarly journals Engineering of the Pyruvate Dehydrogenase Bypass inSaccharomyces cerevisiae: Role of the Cytosolic Mg2+ and Mitochondrial K+ Acetaldehyde Dehydrogenases Ald6p and Ald4p in Acetate Formation during Alcoholic Fermentation

2000 ◽  
Vol 66 (8) ◽  
pp. 3151-3159 ◽  
Author(s):  
Fabienne Remize ◽  
Emilie Andrieu ◽  
Sylvie Dequin
Keyword(s):  
Carbon Flux ◽  
Alcoholic Fermentation ◽  
Pyruvate Decarboxylase ◽  
Wine Yeast ◽  
Wild Type ◽  
Acetate Production ◽  
Wine Yeast Strain ◽  
Acetate Formation ◽  
The Impact

ABSTRACT Acetic acid plays a crucial role in the organoleptic balance of many fermented products. We have investigated the factors controlling the production of acetate by Saccharomyces cerevisiaeduring alcoholic fermentation by metabolic engineering of the enzymatic steps involved in its formation and its utilization. The impact of reduced pyruvate decarboxylase (PDC), limited acetaldehyde dehydrogenase (ACDH), or increased acetoacetyl coenzyme A synthetase (ACS) levels in a strain derived from a wine yeast strain was studied during alcoholic fermentation. In the strain with the PDC1gene deleted exhibiting 25% of the PDC activity of the wild type, no significant differences were observed in the acetate yield or in the amounts of secondary metabolites formed. A strain overexpressingACS2 and displaying a four- to sevenfold increase in ACS activity did not produce reduced acetate levels. In contrast, strains with one or two disrupted copies of ALD6, encoding the cytosolic Mg2+-activated NADP-dependent ACDH and exhibiting 60 and 30% of wild-type ACDH activity, showed a substantial decrease in acetate yield (the acetate production was 75 and 40% of wild-type production, respectively). This decrease was associated with a rerouting of carbon flux towards the formation of glycerol, succinate, and butanediol. The deletion of ALD4, encoding the mitochondrial K+-activated NAD(P)-linked ACDH, had no effect on the amount of acetate formed. In contrast, a strain lacking both Ald6p and Ald4p exhibited a long delay in growth and acetate production, suggesting that Ald4p can partially replace the Ald6p isoform. Moreover, the ald6 ald4 double mutant was still able to ferment large amounts of sugar and to produce acetate, suggesting the contribution of another member(s) of the ALDfamily.

Regulation of p105weel and p34cdc2 during meiosis in Schizosaccharomyces pombe

1992 ◽  
Vol 70 (10-11) ◽  
pp. 1088-1096 ◽  
Author(s):  
Maleki Daya-Makin ◽  
Philippe Szankasi ◽  
Liren Tang ◽  
Diana MacRae ◽  
Steven L. Pelech
Keyword(s):  
Protein Kinase ◽  
Schizosaccharomyces Pombe ◽  
Thermal Inactivation ◽  
State Level ◽  
Fold Increase ◽  
Histone H1 ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Nutritional Conditions ◽  
Tyrosyl Phosphorylation

Temperature-sensitive pat1 mutants of the fission yeast Schizosaccharomyces pombe can be induced to undergo meiosis at the restrictive temperature, irrespective of the mat1 configuration and the nutritional conditions. Using a combination of exit from stationary phase and thermal inactivation of the 52-kilodalton protein kinase that is encoded by the pat1 (also called ran1) gene, highly synchronous meiotic cultures were obtained. Synthesis and tyrosyl phosphorylation of p34cdc2 was evident during meiotic G1 and S phases. During this period there was increased expression of p105wee1, a protein kinase implicated in the tyrosyl phosphorylation of p34cdc2. Following a relatively brief G2 period, during which a reduction in the steady-state level of p105wee1 occurred, there was an approximately 19-fold increase in the histone H1 phosphotransferase activity of p34cdc2. Only a single peak of histone H1 kinase activation was observed, which implies that unlike meiosis in amphibians and echinoderms, p34cdc2 is functional only during one of the meiotic divisions in S. pombe, presumably meiosis II. Stimulation of the kinase activity of p34cdc2 was associated with its tyrosyl dephosphorylation. This is analogous to mitotic M phase and suggests parallels in the mechanism of activation of p34cdc2 during mitosis and one of the meiotic divisions in S. pombe.Key words: wee1, cdc2, ran1, cell cycle, meiosis.

scholarly journals High-Level Acetaldehyde Production in Lactococcus lactis by Metabolic Engineering

2005 ◽  
Vol 71 (2) ◽  
pp. 1109-1113 ◽  
Author(s):  
Roger S. Bongers ◽  
Marcel H. N. Hoefnagel ◽  
Michiel Kleerebezem
Keyword(s):  
Metabolic Engineering ◽  
Lactococcus Lactis ◽  
Zymomonas Mobilis ◽  
Nadh Oxidase ◽  
Pyruvate Decarboxylase ◽  
Resting Cells ◽  
Anaerobic Conditions ◽  
High Level ◽  
Acetaldehyde Production ◽  
Combined Overexpression

ABSTRACT Efficient conversion of glucose to acetaldehyde is achieved by nisin-controlled overexpression of Zymomonas mobilis pyruvate decarboxylase (pdc) and Lactococcus lactis NADH oxidase (nox) in L. lactis. In resting cells, almost 50% of the glucose consumed could be redirected towards acetaldehyde by combined overexpression of pdc and nox under anaerobic conditions.

scholarly journals Neutrophils autoinactivate secretory products by myeloperoxidase- catalyzed oxidation

Blood ◽  
1985 ◽  
Vol 65 (2) ◽  
pp. 375-381 ◽  
Author(s):  
RA Clark ◽  
N Borregaard
Keyword(s):  
Vitamin B12 ◽  
Enzyme Inhibitors ◽  
Binding Protein ◽  
Extracellular Fluid ◽  
Kinetic Studies ◽  
Human Neutrophils ◽  
Resting Cells ◽  
Heme Enzyme ◽  
Inflammatory Stimuli ◽  
Secretory Products

Abstract The neutrophil response to inflammatory stimuli involves the formation of reactive oxygen species and secretion of granule enzymes. In studying secretion of vitamin B12 binding protein by human neutrophils, we noted a major decrease in total recoverable activity from the extracellular fluid plus the stimulated cells (54% of resting cells). Recovery of B12 binding protein from neutrophils exposed to phorbol myristate acetate or opsonized zymosan was significantly enhanced on addition of heme enzyme inhibitors (azide, cyanide) or catalase or when halide-free medium was used. The changes in B12 binding protein recovery were attributable entirely to increases in extracellular fluid levels, and cell pellet content was unaffected. These data indicate extracellular destruction of functional B12 binding protein by the halide-dependent heme enzyme myeloperoxidase and H2O2. Kinetic studies demonstrated rapid secretion of B12 binding protein in the first two to five minutes, followed by its inactivation over the next 20 to 30 minutes. A cell-free extract of vitamin B12 binding protein was readily inactivated on exposure to purified myeloperoxidase, H2O2, and a halide. These findings document a functional interaction among products of the neutrophil specific granules (B12 binding protein), azurophil granules (myeloperoxidase), and metabolic burst (H2O2). They provide an interesting model for the modulation of the inflammatory response by oxidation of secretory products of neutrophils.

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