Carcinogen-mediated Alteration of the Rates of Enzyme Synthesis and Degradation

1968 ◽  
Vol 9 (4) ◽  
pp. 276-286 ◽  
Author(s):  
M. Jr. Rechcigl ◽  
G.L. Laqueur
Keyword(s):  
Enzyme Synthesis ◽  
Synthesis And Degradation

scholarly journals The effect of intralysosomal sucrose storage on the turnover of hamster fibroblast lysosomal and Golgi-apparatus enzymes

1976 ◽  
Vol 158 (2) ◽  
pp. 401-407 ◽  
Author(s):  
M J Warburton ◽  
C H Wynn
Keyword(s):  
Golgi Apparatus ◽  
Half Life ◽  
Cellular Protein ◽  
Enzyme Synthesis ◽  
Pulse Labelling ◽  
Sucrose Uptake ◽  
Total Cellular Protein ◽  
Sucrose Storage ◽  
Alkaline Ribonuclease ◽  
Synthesis And Degradation

1. The effect of overloading of hamster fibroblast lysosomes with sucrose on the turnover of lysosomal and Golgi-apparatus enzymes was studied. Arylsulphatase B and UDP-galactose-N-acetylglucosamine galactosyltransferase were chosen as appropriate marker enzymes. The relative contributions of changes in the rates of synthesis and degradation to the increased activities of these enzymes after uptake of sucrose were examined by isotopic-labelling experiments. The effects of sucrose uptake on the degradation of total cellular protein and of the cytoplasmic enzyme, alkaline ribonuclease, were determined for comparative purposes. 2. The rates of enzyme synthesis in the presence and absence of sucrose were compared by pulse-labelling the cells with 14C-labelled amino acids, followed by isolation of purified enzymes and determination of their radioactivity. Sucrose uptake produced increases of 270% and 90% respectively in the rates of synthesis of arylsulphatase B and galactosyltransferase, whereas the rate of synthesis of alkaline ribonuclease was not affected. 3. The rates of degration of the enzymes were estimated by measuring the decay with time of the radioactivity of purified enzymes from prelabelled cells. In the absence of sucrose, the apparent half-lives of arylsulphatase B and galactosyltransferase were about 30 days and 40h respectively. After uptake of sucrose, the half-life of arylsulphatase B decreased to about 10 days and that of galactosyltransferase to 10h. Neither the half-life of alkaline ribonuclease (4 days) nor the rate of degradation of total cellular protein was affected by the uptake of sucrose. 4. These results indicate that the hyperactivity of lysosmal and Golgi-apparatus enzymes after the uptake of sucrose is accompanied by increases in the rates of both synthesis and degradation, and that the increased rates of degradation are insufficient to prevent accumulation of the excess of enzymes synthesized; also that the effects of sucrose uptake are restricted to the vacuolar apparatus.

scholarly journals GENETIC VARIATION AFFECTING THE EXPRESSION OF CATALASE IN DROSOPHILA MELANOGASTER: CORRELATIONS WITH RATES OF ENZYME SYNTHESIS AND DEGRADATION

Genetics ◽  
1984 ◽  
Vol 106 (3) ◽  
pp. 435-448
Author(s):  
Glenn C Bewley ◽  
Cathy C Laurie-Ahlberg
Keyword(s):  
Drosophila Melanogaster ◽  
Steady State ◽  
Natural Populations ◽  
Enzyme Synthesis ◽  
Substitution Lines ◽  
Chromosome Substitution Lines ◽  
Intracellular Degradation ◽  
Steady State Levels ◽  
Catalase Protein ◽  
Synthesis And Degradation

ABSTRACT Both second and third chromosome substitution lines isolated from natural populations of Drosophila melanogaster affect the expression of catalase (EC 1.11.1.6) at both the larval and adult stages of development. In each case, the level of catalase activity is strongly related to the level of catalase-specific cross-reacting material. Turnover studies employing the catalase inhibitor 3-amino-1,2,4-triazole were conducted on a selected number of lines. Although the variation in steady state levels of catalase protein was highly significant among lines, variation in intracellular degradation rate was not. These results suggest that the different steady state levels observed among lines largely reflect different rates of catalase synthesis.

scholarly journals Activities of α-galactosidase and polygalacturonase during hydration of Dalbergia nigra ((Vell.) Fr All. ex Benth.) seeds at different temperatures

2013 ◽  
Vol 35 (1) ◽  
pp. 92-98 ◽  
Author(s):  
Glauciana da Mata Ataíde ◽  
Eduardo Euclydes de Lima e Borges ◽  
José Francisco de Carvalho Gonçalves ◽  
Valéria Monteze Guimarães ◽  
Elisa Monteze Bicalho ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Relative Humidity ◽  
Water Uptake ◽  
Enzyme Synthesis ◽  
High Relative Humidity ◽  
Different Temperatures ◽  
Glucose Synthesis ◽  
Dalbergia Nigra ◽  
Different Origins ◽  
Synthesis And Degradation

Germination is a process that begins with seed water uptake, stimulating enzyme synthesis or activating enzymes already present. The objective of this study was to evaluate variations in monosaccharide reserves and the activities of the α-galactosidase and polygalacturonase enzymes during the hydration of two lots of Dalbergia nigra (Bahia Rosewood) seeds. Seeds from different origins constituted the two lots I and II, classified as high and low vigor, respectively. Both lots were placed in desiccators with a high relative humidity to hydrate and at 15 and 25 °C until levels of 10, 15, 20 and 25% moisture levels in seeds were reached. The seed cotyledons were analyzed for the quantity of monosaccharides and enzyme activity. The control had higher concentrations of xylose and rhamnose, which decreased during hydration until the 15% level was reached, after which concentrations increased again in both lots. Lot I, with a superior quality, showed higher glucose synthesis and degradation during seed hydration. Both enzymes were pre-existing since activity was already present in the seeds without imbibition. The polygalacturonase enzyme increased and the α-galactosidase enzyme remained relatively constant during seed hydration.

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