Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The role of mitochondria in carbon catabolite repression in Saccharomyces cerevisiae was investigated by comparing normal, respiratory competent (RHO) strains with their mitochondrially inherited, respiratory deficient mutant derivatives (rho). Formation of maltase and invertase was used as an indicator system for the effect of carbon catabolite repression on carbon catabolic reactions. Fermentation rates for glucose, maltose and sucrose were the same in RHO and rho strains. Specific activities of maltase and invertase were usually higher in the rho-mutants. A very pronounced difference in invertase levels was observed when cells were grown on maltose; rho-mutants had around 30 times more invertase than their RHO parent strains. The fact that rho-mutants were much less sensitive to carbon catabolite repression of invertase synthesis than their RHO parents was used to search for the mitochondrial factor(s) or function(s) involved in carbon catabolite repression. A possible metabolic influence of mitochondria on this system of regulation was tested after growth of RHO strains under anaerobic conditions (no respiration nor oxidative phosphorylation), in the presence of KCN (respiration inhibited), dinitrophenol (uncoupling of oxidative phosphorylation) and of both inhibitors anaerobic conditions and dinitrophenol had no effect on the extent of invertase repression. KCN reduced the degree of repression but not to the level found in rho-mutants. A combination of both inhibitors gave the same results as with KCN alone. Erythromycin and chloramphenicol were used as specific inhibitors of mitochondrial protein synthesis. Erythromycin prevented the formation of mitochondrial respiratory systems but did not induce rho-mutants under the conditions used. However, repression of invertase was as strong as in the absence of the inhibitor. Chloramphenicol led only to a slight reduction of the respiratory systems and did not affect invertase levels. A combination of both antibiotics had about the same effect as growth in the presence of KCN. The results showed that mitochondria are involved in carbon catabolite repression and they cause an increase in the degree of repression. These effects cannot be due to mere metabolic activities nor to factors made on the mitochondrial protein synthesizing machinery. This regulatory role of mitochondria is observed as long as an intact mitochondrial genome is maintained.
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PMID:The role of mitochondria in carbon catabolite repression in yeast. 79 Jan 58

Erythromycin, an antibiotic used in the treatment of infectious diseases, produces gastrointestinal side effects such as diarrhea. The mechanisms by which erythromycin produces these effects are not known. However, erythromycin has been shown to increase gastrointestinal motor activity and to inhibit intestinal neutral amino acid absorption. Both effects could contribute to the gastrointestinal side effects observed. Because the intestinal systems of amino acid and sugar transport present similar characteristics, the aim of the present work was to determine whether erythromycin also alters D-galactose absorption and sucrase activity in rabbit jejunum. The results show that erythromycin diminishes intestinal D-galactose absorption. This effect seems to be due to an action mainly located on the Na(+)-dependent sugar transport of the mucosal border of the intestinal epithelium. Erythromycin also inhibits the Na(+)-K+ ATPase activity of the enterocyte, which might explain the inhibition of the D-galactose Na(+)-dependent transport. However, a direct action of the erythromycin molecule on the Na(+)-dependent carrier cannot be excluded. Erythromycin did not alter sucrase activity.
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PMID:Effect of erythromycin on D-galactose absorption and sucrase activity in rabbit jejunum. 840 81

Erythromycin has been shown to inhibit the intestinal transport of L-threonine and D-galactose in strips of mucosal jejunum when it was directly added to the incubation medium. Nevertheless, the effect of erythromycin administered therapeutically by intramuscular injection on both the intestinal absorption of nutrients and the intestinal digestive activity, remains unknown. The results obtained show that, firstly, the intestinal absorption of L-threonine is inhibited in animals treated with erythromycin. The kinetic study shows that the effect seems to be mainly due to an alteration of the affinity apparent constant (Kt) of the Na(+)-dependent system of transport located in the mucosal border. However, the Na(+)-dependent L-threonine transport in BBMV was not altered by the treatment with erythromycin. The (Na(+)-K+) ATPase activity in BLMV from treated jejunum was 40% of the activity in control BLMV. Secondly, the treatment with erythromycin did not modify the digestive enzymatic activity of sucrase and aminopeptidase N.
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PMID:Study of the action of intramuscularly administered erythromycin on the L-threonine transport and the digestive enzymatic activity in rabbit jejunum. 876 16