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

Invertase activity from Streptococcus mutans GS-5 has been partially purified and shown to possess beta-fructofuranosidase specificity. The enzyme has a broad pH optimum between pH 5.5 and 7.5 and exhibits maximal activity at 37 C. Fructose, but not the glucose analogue alpha-methyl-d-glucoside, acts as a competitive inhibitor of the enzyme. None of the common glycolytic intermediates or adenine nucleotides had any significant effect on enzyme activity. A molecular weight of approximately 47,000 was estimated for the enzyme. The enzyme does not appear to be catabolically repressed by glucose nor inducible by sucrose. Higher specific activities of the enzyme are observed in fructose or glucose-grown cells compared to sucrose-grown cells. These results are discussed in terms of the regulation of invertase activity in vivo.
J Bacteriol 1973 Sep
PMID:Characterization of invertase activity from cariogenic Streptococcus mutans. 435 68

Evidence suggests that sucrose is the main carbon source for growth of Claviceps spp. in the parasitic condition. The sucrose acts as substrate for an active beta-fructofuranosidase, produced by the fungus, which in the first instance converts the disaccharide into glucose and an oligofructoside. In this way, 50% of the glucose, supplied as sucrose, is made available to the parasite for assimilation. Subsequent action of the enzyme on both sucrose and the oligofructoside leads to the release of more glucose and the formation of additional oligosaccharides. The structures of the main oligosaccharides formed have been elucidated and the interactions of each compound studied. In experiments with purified enzyme in vitro the interaction of the oligosaccharides is rapid but in culture they are assimilated only slowly; in each case some free fructose is liberated. Free fructose is not assimilated in the presence of glucose and, further, inhibits growth at concentrations which might be expected to occur in the parasitic condition. A dual role has been suggested for the enzyme, with sucrose as substrate, in which glucose is made available to the growing parasite, while at the same time transfer of the fructose to form oligosaccharides prevents it from accumulating at inhibitory concentrations. Ultimately, when glucose becomes limiting, the fungus will adapt to fructose assimilation.
Biochem J 1972 Sep
PMID:A -D-fructofuranosidase from Claviceps purpurea. 464 11

A study was made of Penicillium chrysogenum and some other fungi to determine the relative distribution of intra- and extracellular invertase produced by them in submerged fermentation. The proportion of each type of enzyme varied with the organism and the period of fermentation. More of the enzyme initially bound to the mycelium was released into the medium with the progress of fermentation. Differences were observed in the effects of cultural conditions on enzyme production in P. chrysogenum and Saccharomyces cerevisiae. Considerably greater quantities of enzyme were produced by P. chrysogenum and the yeast in both laboratory and large-scale fermentors when sucrose was added continuously than when the same quantities of the sugar were added initially.
Appl Microbiol 1965 Sep
PMID:Invertase production by Penicillium chrysogenum and other fungi in submerged fermentation. 586 55

One of the cyr 1 mutants (cyr 1-2) in yeast produced low levels of adenylate cyclase and cyclic AMP at 25 degrees and was unable to derepress acid phosphatase. Addition of cyclic AMP to the cyr1-2 cultures elevated the level of repressible acid phosphatase activity. The bcy1 mutation, which suppresses the cyr1-2 mutation by allowing activity of a cyclic AMP-independent protein kinase, also allows acid phosphatase synthesis without restoring adenylate cyclase activity. The CYR3 mutant had structurally altered cyclic AMP-dependent protein kinase and was unable to derepress acid phosphatase. The cyr1 locus was different from pho2, pho4 and pho81, which were known to regulate acid phosphatase synthesis. Mutants carrying cyr1-2 and pho80, PHO81c, PHO82 or pho85 mutations, which confer constitutive synthesis of repressible acid phosphatase, produced acid phosphatase. The cyr1-2 mutant produced significantly low levels of invertase and alpha-D-glucosidase. These results indicated that cyclic AMP-dependent protein kinase exerts its function in the synthesis of repressible acid phosphatase and other enzymes.
Genetics 1984 Sep
PMID:Regulation of repressible acid phosphatase by cyclic AMP in Saccharomyces cerevisiae. 609 Feb 71

To determine whether the inhibition of intestinal adaptation by total parenteral nutrition (TPN) in young growing animals is reversible, 130 7-week-old rats with 70% resection of the midportion of the small bowel were given an amino acid and glucose TPN solution parenterally or orally or a chow diet for 10 days. After TPN administration, villous height, crypt depth, DNA and RNA content, RNA:DNA ratio, and sucrase activity were decreased. After returning to 4 weeks of chow feeding, rats given TPN achieved similar body weight and 15% greater intestinal length as compared with rats fed chow from the start, although their jejunal villous height, ileal crypt depth, and RNA:DNA were decreased. Therefore, the inhibition by TPN of intestinal adaptation after intestinal resection in young growing rats is largely reversible. Furthermore, oral feeding of a high-calorie, high-protein liquid diet before feeding of a normal diet appears to promote adaptation after intestinal resection in immature, growing rats.
Surgery 1984 Sep
PMID:Total parenteral nutrition inhibits intestinal adaptive hyperplasia in young rats: reversal by feeding. 620 84

Rats were kept undernourished from birth to 24 days of age. At 17 days of age, the undernourished animals were divided into two groups and then injected with either saline or epidermal growth factor (EGF; 20 micrograms/kg) once a day for 7 days. They were killed 12-14 h after the last injection at which time the animals were 24 days old. During the experimental period the undernourished animals were prevented from weaning. A well-nourished group (weaned) which was injected with saline from 17 to 24 days of age, was also included. Undernutrition by itself significantly decreased body weight and the weight of the oxyntic gland area, antrum, and small intestine. This was also accompanied by a parallel reduction in DNA, RNA, and protein content in the oxyntic gland and small intestine. However, administration of EGF to undernourished rats resulted in a partial reversal of the situation. In undernourished rats, EGF caused significant enhancements in body weight as well as the weight of the gastrointestinal tissues and their protein and nucleic acid content when compared with the saline-treated undernourished controls. Furthermore, the magnitude of stimulation was found to be greater in the oxyntic gland than in the small intestine following EGF administration. The antral or serum gastrin levels were not affected by EGF. In both saline- and EGF-treated undernourished rats, lactase, sucrase, and alkaline phosphatase activities (expressed as total or specific activity) were found to be significantly higher than in the well-nourished animals.(ABSTRACT TRUNCATED AT 250 WORDS)
J Pediatr Gastroenterol Nutr 1984 Sep
PMID:Postnatal undernutrition: effect of epidermal growth factor on growth and function of the gastrointestinal tract in rats. 620 84

The digestion of Neosugar, a mixture of 1F-(1-beta-fructofuranosyl)n-1 sucrose [n = 2, 1-kestose (GF2); n = 3, nystose (GF3); n = 4, 1F-beta-fructofuranosyl nystose (GF4)] was investigated in vitro and in vivo by using the rat. The results obtained were as follows. GF2 and GF3 were not hydrolyzed by a pancreatic homogenate. The GF2- and GF3-hydrolyzing activities of the enzymes in the intestinal mucosa homogenate were negligible compared with the activities of maltase and sucrase. GF2 and GF3 added to the incubation mixture did not affect the activities of sucrase and maltase in the intestinal mucosa. Long-term ingestion of Neosugar did not cause induction or suppression of GF2- and GF3-hydrolyzing enzymes in the small intestine. [U-14C]Neosugar injected intravenously was rapidly excreted in the urine without having undergone any degradation. These results indicate that Neosugar, which consists of GF2, GF3 and GF4, is scarcely hydrolyzed by the digestive enzymes of the gastrointestinal tract and internal organs, and that suggests to us that Neosugar is not utilized as an energy source in the body.
J Nutr 1984 Sep
PMID:Nondigestibility of a new sweetener, "Neosugar," in the rat. 633 83

A single structural gene, SUC2, encodes both secreted and cytoplasmic invertase in Saccharomyces cerevisiae. It is known that the unprocessed polypeptides which differ by a secretion signal sequence are encoded by separate mRNAs. This unusual transcriptional organization raises the question as to the degree to which the transcripts can be independently regulated. To define a system for studying this problem, we examined invertase transcription after various physiological perturbations of cells: rapid catabolite derepression, heat shock, and cell cycle arrest. With each treatment, fluctuations in mRNA levels for both cytoplasmic and secreted invertase were observed. We concluded that (i) catabolite-derepressed synthesis of the mRNAs occurs rapidly after a drop in glucose, is a sustained response, and does not require de novo protein synthesis; (ii) heat shock transcription of both invertase mRNAs is, in contrast, a brief and transient response requiring de novo protein synthesis; and (iii) alpha-mating hormone treatment (G1 phase arrest and release) results in regular and coordinated synthesis of both mRNAs midway between rounds of histone mRNA synthesis. We propose that invertase mRNA regulation involves constitutively synthesized transcriptional factors (observed during catabolite derepression) and transient factors (observed during heat shock and possibly during synchronous growth). Moreover, the mRNA levels for secreted and cytoplasmic invertase can be independently regulated.
Mol Cell Biol 1984 Sep
PMID:Cytoplasmic and secreted Saccharomyces cerevisiae invertase mRNAs encoded by one gene can be differentially or coordinately regulated. 638 45

The antinutritional effect caused by the ingestion of lectins from two Brazilian varieties of beans: Rico 23 and Jalo, was studied in rats. The two varieties were selected in a previous screening of toxicity in rats: one of them (Jalo) was lethal, and the other (Rico 23) was not, when injected intra-peritoneally. Different amounts of each one of the lectins were added to casein experimental diets and fed to rats. The amount of protein (casein) also varied from 5% to 20%. The addition to the diet of 1% lectins from the Jalo variety caused a growth depression, as well as a decrease in food efficiency ratio and serum glucose; also, it reduced the maltase and invertase activity of the intestinal mucosa. All these effects appeared when the protein contents in the rations were 5% or 10%. At the 20% level only a depression of the maltase activity was observed. Similar effects were shown by the lectins of the Rico 23 variety, but only when added in a higher (5%) percentage to the diet. The phosphatase and protease activity were not changed by any of the lectins. The inhibitor activity that occurred in vivo was not detected in vitro.
Arch Latinoam Nutr 1984 Sep
PMID:[Antinutritional effect of phytohemagglutinins of Phaseolus vulgaris L]. 639 38

Jejunal fluid and mucosal tissue were obtained simultaneously from the same jejunal site in a group of 29 children by a modified biopsy procedure. Lactase, maltase, and sucrase activities were measured in both fluid and mucosal specimens using the same analytical method. The fluid enzyme activities showed highly significant positive correlations with the same enzyme activity in the relevant tissue samples. Relative concentrations of disaccharidase enzymes represented by sucrase: lactase activity ratios also showed a highly significant positive correlation between fluid and tissue. This close relation suggests that the mucosa is the sole or predominant source of disaccharidase activity in the intestinal fluid. The results of kinetic studies comparing tissue and fluid enzyme characteristics also indicate a mucosal origin for the fluid enzyme activities. We conclude that disaccharidase activities in jejunal fluid reflect closely local tissue values and that these measurements may be useful in assessing mucosal enzyme activity in infants in whom jejunal biopsy is not possible.
Arch Dis Child 1983 Sep
PMID:Disaccharidase activities in jejunal fluid. 641 85


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>