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PubMed1977

Preparation of renal cortex basal-lateral and bursh border membranes. Localization of adenylate cyclase and guanylate cyclase activities.

Luminal brush border and contraluminal basal-lateral segments of the plasma membrane from the same kidney cortex were prepared. The brush border membrane preparation was enriched in trehalase and gamma-glutamyltranspeptidase, whereas the basal-lateral membrane preparation was enriched in (Na+ + K+1)-ATPase. However, the specific activity of (Na+ + K+)-ATPase in brush border membranes also increased relative to that in the crude plasma membrane fraction, suggesting that (Na+ + K+)-ATPase may be an intrinsic constituent of the renal brush border membrane in addition to being prevalent in the basal-lateral membrane. Adenylate cyclase had the same distribution pattern as (Na+ + K+)-ATPase, i.e. higher specific activity in basal-lateral membranes and present in brush border membranes. Adenylate cyclase in both membrane preparations was stimulated by parathyroid hormone, calcitonin, epinephrine, prostaglandins and 5'-guanylylimidodiphosphate. When the agonists were used in combination enhancements were additive. In contrast to the distribution of adenylate cyclase, guanylate cyclase was found in the cytosol and in basal-lateral membranes with a maximal specific activity (NaN3 plus Triton X-100) 10-fold that in brush border membranes. ATP enhanced guanylate cyclase activity only in basal-lateral membranes. It is proposed that guanylate cyclase, in addition to (Na+ + K+)-ATPase, be used as an enzyme "marker" for the renal basal-lateral membrane.

Adenosine Triphosphate↗
PubMed1994

Enzymic synthesis of alpha- and beta-D-glucosides of 1-deoxynojirimycin and their glycosidase inhibitory activities.

1-Deoxynojirimycin (1) is a potent inhibitor of mammalian and rice alpha-glucosidase. Several glucosides of 1 were synthesized by use of the native and immobilized enzyme and their effect on various enzymes was investigated. Transglucosylation reactions using rice alpha-glucosidase, yeast alpha- and beta-glucosidases purified from Rhodotorula lactosa were performed with maltose or cellobiose as a glucose donor and N-(benzyloxycarbonyl)-1-deoxynojirimycin (2) as an acceptor. The transglucosylation reaction using native rice alpha-glucosidase afforded 3-O-alpha-D-glucopyranosyl-N-(benzyloxycarbonyl)-1-deoxynojirimycin (4), 4-O-alpha-D-glucopyranosyl-N-(benzyloxycarbonyl)-1-deoxynojirimycin (5), and 2-O-alpha-D-glucopyranosyl-N-(benzyloxycarbonyl)-1-deoxynojirimycin (3) in yields of 40, 13, and 2%, respectively, after 30 min. The transglucosylation reaction using immobilized rice alpha-glucosidase was similar to that using the native enzyme. In the system using native yeast alpha-glucosidase, 3, 5, and 4 were formed in yields of 34, 13, and 6%, respectively, after 15 h. The immobilization of yeast alpha-glucosidase caused a significant decrease in transglucosylation activity. Yeast beta-glucosidase showed a high transglucosylation activity and incubation with the reaction system afforded 2-O-beta-D-glucopyranosyl-N-(benzyloxycarbonyl)-1-deoxynojirimycin (6) and 4-O-beta-D-glucopyranosyl-N-(benzyloxycarbonyl)-1-deoxynojirimycin (7) in yields of 69 and 3%, respectively, after 3 h. The transglucosylation reaction using immobilized yeast beta-glucosidase preferentially afforded 6 in a yield of 73% after 3 h. After removal of N-benzyloxycarbonyl group from the product glucosides, their glycosidase inhibitory activities were measured. 3-O-alpha-D-Glucopyranosyl-1-deoxynojirimycin (9) retained the potent inhibition of 1 against rat intestinal sucrase activity and was more effective than 1 against rice alpha-glucosidase. 4-O-alpha-D-Glucopyranosyl-1-deoxynojirimycin (10) retained the potency of 1 against rat intestinal sucrase and isomaltase. 2-O-alpha-D-Glucopyranosyl-1-deoxynojirimycin (8) was more effective than 1 against trehalases.

1-Deoxynojirimycin↗
PubMed1990

Heat shock induces enzymes of trehalose metabolism, trehalose accumulation, and thermotolerance in Schizosaccharomyces pombe, even in the presence of cycloheximide.

Exponentially growing cells of the fission yeast, Schizosaccharomyces pombe, contained virtually no trehalose at 27 degrees C but rapidly accumulated large quantities during heat shock at 40 degrees C. Activities of trehalose-6-phosphate synthase and trehalase also increased upon heat shock. Thermotolerance of the cells, measured as survival at 52 degrees C, increased in parallel to trehalose accumulation and decreased in parallel to the trehalose levels when cells were shifted back to 27 degrees C. Trehalose levels, activities of enzymes of trehalose metabolism and thermotolerance strongly increased upon heat shock even in the presence of cycloheximide, indicating that none of these effects requires protein synthesis. The data support the hypothesis that trehalose acts as a thermoprotectant in Schizosaccharomyces pombe.

Cycloheximide↗
PubMed1994

Is thermotolerance of yeast dependent on trehalose accumulation?

During heat stress, trehalose concentration increases in yeast cells in parallel to thermotolerance. This parallelism suggested that trehalose mediated thermotolerance. We show in this work that, under certain conditions, trehalose accumulation and increase in thermotolerance do not go in parallel. A mutant deficient in the trehalose-degrading neutral trehalase shows, after shift from 40 degrees C to 30 degrees C, low thermotolerance in spite of a high trehalose concentration. When glucose is added to stationary yeast cells with high trehalose concentration and high thermotolerance, trehalose concentration decreases while thermotolerance remains high. A mutant deficient in ubiquitin-conjugating genes, ubc4ubc5, shows during exponential growth a low trehalose concentration, but a high thermotolerance, in contrast to wild-type cells. Because the ubc4ubc5 mutant synthesizes heat-shock proteins constitutively, it is proposed that, under these conditions, accumulation of heat-shock proteins, and not trehalose [corrected], mediates thermotolerance.

Gene Deletion↗
PubMed1986

Hormonal control of the intestinal brush border enzyme activities in developing anuran amphibians. I. Effects of hydrocortisone and insulin during and after spontaneous metamorphosis.

The effects of hydrocortisone and insulin on the intestinal brush border membrane enzymatic activities in an anuran amphibian, Alytes obstetricans, were investigated at the end of spontaneous metamorphosis and 2 weeks after its completion. At the end of metamorphosis, the brush border is differentiating in the apical region of a developing neoformed epithelium. Two weeks after the completion of metamorphosis, this epithelium is entirely formed. The animals received one hormone injection per day for 2 or 3 days running (hydrocortisone: 1, 5, or 25 micrograms/g body wt/day; insulin: 0.5, 1, or 5 mU/g body wt/day). The hydrolases studied were three glucosidases (maltase, glucoamylase, trehalase), gamma-glutamyl-transferase and alkaline phosphatase. In animals reaching the end of metamorphosis, hormonal treatments rarely modify the three glucosidase activities. Two weeks after metamorphosis, a 5 microgram/g body wt/day hydrocortisone injection usually results in a significant increase of the three glucosidase activities. Conversely, a 0.5 mU/g body wt/day insulin injection induced a marked decrease in these activities. At the end of metamorphosis, hydrocortisone has variable effects on gamma-glutamyl-transferase activity; insulin, however, does not significantly modify this activity. Two weeks later, insulin and sometimes hydrocortisone inhibit gamma-glutamyl-transferase activity. Whatever the developmental stage is, hydrocortisone is able to stimulate alkaline phosphatase activity. At the end of metamorphosis, insulin has no influence on this activity, but 2 weeks after metamorphosis, low doses of the hormone (0.5 mU/g body wt/day) significantly reduce it. These results emphasize the possibility that after spontaneous metamorphosis the enzymatic activities of the new intestinal brush border are hormone controlled. This control could be related to the development of the interrenal and pancreatic islet functions.

Alkaline Phosphatase↗
PubMed1987

Hormonal control of the intestinal brush border enzyme activities in developing anuran amphibians. II. Effects of glucocorticoids and insulin during experimental metamorphosis.

The effects of glucocorticoids (hydrocortisone, dexamethasone) and insulin on enzymatic activities of the intestinal brush border membrane were investigated in an anuran amphibian, Alytes obstetricians, before and during experimental metamorphosis produced by immersion into a thyroxine solution. During experimental metamorphosis, a new epithelium (secondary epithelium) replaces the degenerating primary epithelium. The enzymes studied were three glucidases (maltase, glucoamylase, trehalase) and alkaline phosphatase. In tadpoles reaching the end of premetamorphosis, hormones were injected every day (hydrocortisone, dexamethasone: 25 micrograms/g body wt/day; insulin: 5 mU/g body wt/day, for 3 and occasionally 6 consecutive days. Under such conditions, most of the activities in the primary epithelium increased or remained stable. In animals which completed experimental metamorphosis, the secondary epithelium formed. Hydrocortisone (25 micrograms/g body wt/day) and insulin (5 mU/g body wt/day) treatments significantly decreased the enzymatic activities of the new brush border membrane in animals which received one hydrocortisone and/or insulin injection per day, during 3 consecutive days. Such results, which previously had not been obtained systematically in spontaneously metamorphosing tadpoles (El Maraghi-Ater, Mesnard, and Hourdry (1986). Gen. Comp. Endocrinol. 61, 53-63), emphasize the relative independence of the intestinal metabolism during experimental and spontaneous metamorphosis.

Alkaline Phosphatase↗
PubMed1995

Influence of copper, manganese and pH on the growth and several enzyme activities in mycorrhizal fungus Amanita muscaria.

The effects of various concentrations of copper, manganese and pH on the growth and several enzyme activities of mycorrhizal fungus Amanita muscaria were investigated. Cu (5-25 mg l-1) and lower pH (3.0-4.0) strongly inhibited the mycelial growth (dry weight), however, the protein content was not affected evidently. Some enzyme activities were lower as the Cu and Mn concentrations were higher and other enzymes had the maximum values at the specified concentration. The activities of the following enzymes were significantly correlated with the fungal growth after the treatment with Cu: G6PDH, MTLDH and trehalase, and with Mn: G6PDH, MTLDH and alpha-mannosidase respectively. Measurement of these enzyme activities might provide a useful biochemical criterion for the evaluation of the fungitoxicity of soil contaminated by copper or manganese.

Acid Phosphatase↗
PubMed1989

Comparative studies between the glucose-induced phosphorylation signal and the heat shock response in mutants of Saccharomyces cerevisiae.

Addition of glucose to derepressed yeast cells, as well as a heat shock treatment, trigger the phosphorylation of trehalase and of trehalose-6-phosphate synthase. In the present paper, evidence is provided for the requirement of the RAS protein in the transduction of the glucose signal. On the other hand, a heat shock at 52 degrees C for 2 min was able to produce a significant phosphorylating effect even in mutant strains deficient in the GTP binding protein. Moreover, it was shown that this treatment does not affect exclusively the cAMP-dependent protein kinase. The use of a series of mutant strains confirmed that low levels of cAMP favor thermotolerance; the role of trehalose in yeast viability is also discussed.

Cyclic AMP↗
PubMed1992

Diet fatty acid composition, age and rat jejunal microvillus enzyme activities.

1. Lactase, sucrase, maltase, trehalase and alkaline phosphatase activities of rat proximal jejunum were measured in 3, 6, 9, 12, 18 and 24-month-old rats fed with diets differing in their fatty acid composition. 2. A drop of 47-53% of the specific enzyme activity was observed with disaccharidases against a decrease of 71% for alkaline phosphatase in the 24-month-old rats compared to the 3-month-old rats. 3. Changes in dietary fatty acid composition, either in the saturated or monounsaturated ratio, or in the polyunsaturated fatty acid composition, did not significantly interfere with this aging effect.

Aging↗
PubMed1994

Trehalose metabolism in Saccharomyces cerevisiae during heat-shock.

When different strains of Saccharomyces cerevisiae grown at 23 degrees C were transferred to 36 degrees C, trehalose and glycogen were accumulated. Glycogen accumulation was less extensive and its synthesis started at least 15 min after initiation of trehalose synthesis. The steady-state intracellular concentration of trehalose increased simultaneously with the activities of the enzymes trehalose-6P synthase, UDPG-pyrophosphorylase, phosphoglucomutase and trehalase. A small but significant change was observed in hexokinase activity. Our results directly implicate isoform PII of hexokinase and the minor isoform of phosphoglucomutase in the pathway of trehalose formation during heat-shock. We also showed that the major isoform of phosphoglucomutase increased in activity but was not essential for trehalose accumulation. Studies with the glucose uptake system indicated that trehalose accumulation could be primarily determined by intracellular availability of substrates due to the increase in the rate of glucose uptake. The increased uptake appears to have two components: a kinetic effect of temperature upon glucose transporters and an increase in the numbers of molecules of the transporters, probably mediated by synthesis de novo.

Glucosyltransferases↗
PubMed1992

Intestinal disaccharidases in the house musk shrew, Suncus murinus: occurrence of sucrase deficiency.

1. Disaccharidase activities of the small-intestinal brush border membrane were studied in six laboratory lines of the house musk shrew, Suncus murinus. 2. Sucrase activity was detected in all shrews of one line, but not in any shrew of three lines. In the other two lines it was found in some shrews, but not in the others. 3. Maltase, isomaltase, trehalase and lactase activities were found in all shrews of all the lines examined. 4. Sucrase was normally associated with isomaltase to form an enzyme complex. 5. Detergent-solubilized isomaltase, whether associated with sucrase or not, was inhibited by antibodies against rabbit sucrase-isomaltase to almost the same extent as the rabbit one, suggesting that isomaltase is not affected by a mutation(s) in sucrase.

Animals↗
PubMed1992

Intestinal disaccharidases in five species of phyllostomoid bats.

1. Intestinal disaccharidases were studied in nectarivorous (Leptonycteris curasoae and Glossophaga soricina), frugivorous (Artibeus jamaicensis and Sturnira lilium), and insectivorous (Pteronotus personatus) adult bats. 2. Adult bats lacked measurable lactase activity. With the exception of trehalase activity, which was present only in P. personatus, nectar- and fruit-eating bats exhibited higher disaccharidase activities standardized by intestinal nominal area than insect-eating P. personatus. 3. Maltase and sucrase activities were significantly linearly correlated. 4. Apparent affinity of sucrase varied almost 5-fold among species. This variation may reflect unstirred layer effects resulting from sucrase being a membrane bound enzyme rather than differences in the "true" affinity of sucrase in solution. 5. Passerine birds showed higher maltase activity per unit of sucrase activity than bats and hummingbirds. Maximal sucrase and maltase activities standardized per intestinal nominal area are 1.5-2 times higher in hummingbirds than in nectar-feeding bats.

Animals↗
PubMed1996

A cyclic phosphonamidate analogue of glucose as a selective inhibitor of inverting glycosidases.

Recent work in the synthesis of cyclic phosphonate analogues of glucose [Darrow, J.W.; Drueckhammer, D.G. (1994) J. Org. Chem. 1994, 59, 2976] has been extended to the synthesis of a corresponding phosphonamidate analogue. A phosphonate salt, phosphonate methyl ester, and phosphonamidate analogue were tested as inhibitors of two inverting alpha-glycosidases, (trehalase and glucoamylase), and two retaining glycosidases, (alpha-glucosidase and beta-glucosidase). No inhibition of any of these enzymes was observed with the phosphonate salt or methyl ester. However, the phosphonamidate gave moderate competitive inhibition of the two inverting glycosidases and the retaining alpha-glucosidase but no inhibition of beta-glucosidase. The phosphonamidate showed enhanced binding relative to a simple monosaccharide only with the inverting glycosidases. This enhanced binding is believed to be due to hydrogen bonding interactions between the phosphonamidate group and two active site carboxylate residues implicated in catalysis. The selectivity toward inverting glycosidases is consistent with differences in distance of an active site carboxylate from the anomeric carbon of the glycoside substrate for the inverting versus the retaining glycosidases.

Animals↗
PubMed1997

The role of the trehalose transporter during germination.

Previous studies on the resistance of yeast cells to dehydration pointed towards the protective role of trehalose and the importance of the specific trehalose transporter in guaranteeing survival. The present report demonstrates that the trehalose transporter is essential during the germination process in order to translocate trehalose from the cytosol to the external environment. Diploids that lack the trehalose transporter germinate poorly and do not form 4 spore tetrads although they accumulate trehalose and show trehalase activity. Furthermore, addition of exogenous trehalose to the germination medium enhances germination and normal segregation. The ability to transport trehalose is dominant and seems to be related to a single gene.

Biological Transport↗
PubMed1999

Polyhydroxylated pyrrolidine and pyrrolizidine alkaloids from Hyancinthoides non-scripta and Scilla campanulata.

Aqueous ethanol extracts from the immature fruits and stalks of bluebell (Hyacinthoides non-scripta) were subjected to various ion-exchange column chromatographic steps to give 1,4-dideoxy-1,4-imino-D-arabinitol (1),2(R),5(R)-bis(hydroxymethyl)-3(R),4(R)-dihydroxypyrrolidine (DMDP) (2), 6-deoxy-6-C-(2,5-dihydroxyhexyl)-DMDP (3),2,5-dideoxy-2,5-imino-DL-glycero-D-manno-heptitol (homoDMDP)(4),homoDMDP-7-O-apioside (5), homoDMDP-7-O-beta-D-xylopyranoside (6), (1S*,2R*,3R*,5R*,7aR*)-1,2-dihydroxy-3,5- dihydroxymethylpyrrolizidine (7), and (1S*,2R*,3R*,5R*,6R*,7R*,7aR*)-3-hydroxymethyl-5-methyl-1,2,6,7 tetrahydroxypyrrolizidine (8). Bulbs of Scilla campanulata (Hyacinthaceae) yielded (1S*,2R*,3R*,5S*,7aR*)-1,2-dihydroxy-3,5-dihydroxy-methylpyrrol izidine (9) in addition to compounds 1-7. Compounds 3,6,7,8, and 9 are new natural products. Compound 4 is a potent competitive inhibitor with K(i) values of 1.5 microM for Caldocellum saccharolyticum beta-glucosidase and 2.2 microM for bovine liver beta-galactosidase. The 7-O-beta-D xyloside 6 was a stronger competitive inhibitor than 4 of C saccharolyticum beta-glucosidase and rat intestinal lactase, with K(i) values of 0.06 and 0.07 microM, respectively, but a weaker inhibitor of bovine liver beta-galactosidase. Furthermore, compound 4 is also a competitive inhibitor (K(i) = 1.8 microM) of porcine kidney trehalase, but 6 was inactive against this enzyme.

Alkaloids↗
PubMed1989

Developmental profile of DNA synthesis and hydrolase activities in human fetal kidney.

This study provides original data on human fetal kidney developing during the 13th to 18th week of gestation. The parameters evaluated were DNA synthesis and the activities of 5 hydrolases which are considered as good markers of the brush border membrane differentiation. The conclusions are that DNA synthesis decreased slightly from the 16th to 18th week. The activities of maltase, trehalase, alkaline phosphatase and leucylnapthylamidase remained nearly stable during the studied period. Only the gamma-glutamyltransferase activity decreased significantly between the 15th and 16th week, then it returned close to the 13th week value. The current results suggest that during the 13-18 week period of gestation, cell proliferation is slowed down while maturation of some enzymic activities of the brush border are not importantly modified. The present basic data might be used as reference standards by investigators in the field of human nephrogenesis.

Alkaline Phosphatase↗
PubMed2003

Trehalose metabolism genes in Caenorhabditis elegans and filarial nematodes.

The sugar trehalose is claimed to be important in the physiology of nematodes where it may function in sugar transport, energy storage and protection against environmental stresses. In this study we investigated the role of trehalose metabolism in nematodes, using Caenorhabditis elegans as a model, and also identified complementary DNA clones putatively encoding genes involved in trehalose pathways in filarial nematodes. In C. elegans two putative trehalose-6-phosphate synthase (tps) genes encode the enzymes that catalyse trehalose synthesis and five putative trehalase (tre) genes encode enzymes catalysing hydrolysis of the sugar. We showed by RT-PCR or Northern analysis that each of these genes is expressed as mRNA at all stages of the C. elegans life cycle. Database searches and sequencing of expressed sequence tag clones revealed that at least one tps gene and two tre genes are expressed in the filarial nematode Brugia malayi, while one tps gene and at least one tre gene were identified for Onchocerca volvulus. We used the feeding method of RNA interference in C. elegans to knock down temporarily the expression of each of the tps and tre genes. Semiquantitative RT-PCR analysis confirmed that expression of each gene was silenced by RNA interference. We did not observe an obvious phenotype for any of the genes silenced individually but gas-chromatographic analysis showed >90% decline in trehalose levels when both tps genes were targeted simultaneously. This decline in trehalose content did not affect viability or development of the nematodes.

Amino Acid Sequence↗
PubMed2002

Trehalose-hydrolysing enzymes of Metarhizium anisopliae and their role in pathogenesis of the tobacco hornworm, Manduca sexta.

Trehalose is the main haemolymph sugar in most insects including the tobacco hornworm, Manduca sexta, and is potentially a prime target for an invading pathogenic fungus. There was considerably more trehalose-hydrolysing activity in the haemolymph of caterpillars infected with Metarhizium anisopliae than in controls. This appeared to be due primarily to additional isoforms; one of which could also hydrolyse maltose and was designated an alpha-glucosidase. A comparable isoform was identified in in vitro culture of the fungus, supporting a fungal origin for the in vivo enzyme. The in vitro fungal enzyme, alpha-glucosidase-1 (alpha-gluc-1), was purified to homogeneity and partially characterised. A study with the trehalase inhibitor trehazolin and C14 trehalose suggested that extracellular hydrolysis is important for fungal mobilisation of trehalose. Haemolymph glucose increases significantly during mycosis of tobacco hornworm larvae by M. anisopliae, consistent with the hydrolysis of trehalose by extracellular fungal enzymes. The implications for the host insect are discussed.

Animals↗