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)

Fructose has recently received much attention due to renewed interest in natural sweeteners. In addition, fructose has some advantages to sucrose in sweetness, solubility, viscosity, and dental health characteristics. Fructose is deposited as storage fructans of the inulin (beta-1,2) type in tubers and rhizomes of the Compositae family. The utilization of the Jerusalem artichoke (Helianthus tuberosus) tuber as a source of fructose syrup is discussed. This plant has the potential to produce more sugar per acre than corn or sugar beets. In addition, the artichoke has higher frost resistance and lower heat unit requirements than corn and is somewhat more tolerant to low moisture conditions than sugar beets. A high quality fructose syrup can be produced from artichoke tubers. The extraction step was found to be particularly important since development of adverse colors and flavors must be prevented. The fructans may be acid or enzyme hydrolyzed but the latter method gave a higher quality syrup. Ion-exchange resins and activated charcoal were effective in removing coloring and flavoring materials, and also reduced other noncarbohydrate constituents. Since the enzymatic hydrolysis of the fructans is an attractive alternative to acid hydrolysis, a process was developed for producing and purifying a special beta-fructofuranosidase (inulase) from Saccharomyces fragilis. Inulase has a much higher specificity for fructans than commerically available beta-fructofuranosidase (invertase).
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PMID:Preparation of high-fructose syrup from the tubers of the Jerusalem artichoke (Helianthus tuberosus L. 4 85

Recent studies have demonstrated that the human intestinal enzymes of carbohydrate digestion and metabolism can be regulated by dietary sugars. These studies have utilized direct assay of intestinal mucosal enzyme activity. Mucosa has been obtained by the use of peroral jejunal biopsy techniques which provide 10-15 mg of mucosa in a safe, simple and reproducible manner. Dietary sucrose, as compared to dietary glucose, increases the activities of the jejunal disaccharidases, sucrase and maltase, but not lactase. Fructose reproduces the sucrose effect and appears to be the active principle in the sucrose molecule. Lactose deprivation or lactose feeding does not alter lactase activity. Fructose has been useful in treating one patient with sucrase-isomaltase deficiency. Jejunal glycolytic enzyme activities are also regulated by dietary sugars. Certain enzymes are highest with specific dietary carbohydrates, lower with other sugars and lowest on a carbohydrate-free diet. The regulation of human jejunal glycolytic enzyme activity takes place in hours, whereas the change in disaccharidase activity occurs in 2-5 days. The mechanism of this regulation is not known. Additional investigations have shown that jejunal glycolytic enzyme activities but not the disaccharidases are controlled by oral folic acid as well. This effect occurs within 1 day also. The mechanism is unknown. Large doses of folate have been of benefit in a few patients with certain glycolytic enzyme deficiency states. Preliminary studies have demonstrated that selected patients with chronic undiagnosed intestinal disorders fail to manifest an adaptive response of their jejunal glycolytic enzyme activities to dietary sugars. This condition has been termed a "maladaptation syndrome.".
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PMID:Diet and intestinal enzyme adaptation: implications for gastrointestinal disorders. 16 4

Male rats of the ASL Wistar strain were fed from weaning on starch, fructose or carbohydrate-free diets for 4 and 12 weeks. In addition, further groups were fed for 24 weeks on starch, sucrose or carbohydrate-free diets. Livers were examined for gross composition, glucose-6-phosphatase activity and in vitro lipogenesis and glucose oxidation. Intestinal sucrase was also measured. Dietary fructose and the carbohydrate-free diet induced an enlargement of the livers after 12 weeks feeding, when expressed per 100g body weight, and at the same time, an increased fat content. Fructose caused an increase in liver glucose-6-phosphatase after 4 weeks, which persisted after 12 weeks, and a similar increase was observed after 24 weeks feeding on sucrose. Fructose produced an increase in intestinal sucrose after 4 weeks, but this did not persist and there was no increase evident after 12 weeks feeding, nor after 24 weeks feeding on sucrose. Fructose markedly depressed the in vitro lipogenesis and glucose oxidation in liver slices. This was evident after 4 weeks feeding and also after 12 weeks when the effect of age showed as a fall in both these parameters in the control group of animals. The carbohydrate-free diet caused an increase in liver glucose-6-phosphatase after 4 weeks, a smaller increase after 12 weeks, and there was no increase apparent when feeding was continued for 24 weeks. Apparently due to the absence of substrate, the intestinal sucrose activity fell to less than half after 4 weeks and to negligible levels after 12 and 24 weeks on carbohydrate-free diet. In vitro liver lipogenesis and glucose oxidation were depressed after 4 and 12 weeks in a similar way to the fructose diet. On both these diets the rise in liver glucose-6-phosphatase appeared to parallel the fall in liver lipogeneis and glucose oxidation.
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PMID:Some metabolic effects of prolonged feeding of starch, sucrose, fructose and carbohydrate-free diet in the rat. 18 97

An invertase from Ricinus communis leaves was purified 4,400-fold. The preparation was homogeneous by criteria of gel electrophoresis, gel permeation, adsorption, and ionic exchange chromatography. One optimum pH at 3.5 was observed with crude invertase; however, purified preparations showed two optima, at pH 3.5 and 5.5. Addition of bovine serum albumin restored one maximum at pH 3.5 and elicited a 30% activation of the invertase. The effect was caused by many other proteins and by heparin, dextran sulfate, and polyvinylpyrrolidone. Fructose, fructose 1,6-diphosphate, maleic, trans-aconitic, malic, and ascorbic acids were simple competitive inhibitors of the purified enzyme. Glucose was a noncompetitive inhibitor. The activation by proteins suppressed these inhibitory effects. The minimum concentration of activator necessary to reach the maximal activation or "point of optimal activation" was always reached at a concentration of 1 X 10(-6) M, independently of the nature of the activator, when 8.6 X 10(-12) mol of enzyme were used. Apparent molecular weight determinations of the enzyme in the presence and absence of activator and molecular weight determinations based on determinations of the point of optimal activation suggested that the purified enzyme is a heptamer (Mr of 77,900, Stokes radius 32 A, frictional ration f/fo 1.1, partial specific volume 0.749 ml/g) and that the activated form is a trimer consisting of two enzyme subunits and one activator molecule. The activation was lost by dilution of the trimer. The enzyme subunit, as isolated by gel filtration in the presence of sodium dodecyl sulfate (Mr 11,000) was inactive but quickly regained activity upon removal of sodium dodecyl sulfate.
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PMID:Purification and characterization of Ricinus communis invertase. 398 40

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.
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PMID:Characterization of invertase activity from cariogenic Streptococcus mutans. 435 68

The specific effect of dietary sugars on jejunal disaccharidase activity in seven normal nonfasted male volunteers was studied. The sugars tested were sucrose, maltose, lactose, glucose, fructose, and galactose. Comparisons were made of the effects of each sugar in an isocaloric liquid diet. In all subjects, sucrose feeding, as compared to glucose feeding, significantly increased jejunal sucrase (S) and maltase (M) activities, but not lactase (L) activity. The S/L and M/L ratios increased to a significant degree. Fructose feeding, in two subjects, gave results similar to sucrose when comparing fructose and glucose diets. One subject was fed lactose, galactose, and maltose. These sugars, compared to glucose, did not increase disaccharidase activity. Fructose appears to be the active principle in the sucrose molecule. These results demonstrate that specific dietary sugars can alter enzyme activity in the small intestine of man in a specific fashion. Sucrose and fructose are able to regulate sucrase and maltase activity. Dietary alteration of intestinal enzymes may represent a suitable system for studying the regulation of enzyme activity in man.
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PMID:Control of jejunal sucrase and maltase activity by dietary sucrose or fructose in man. A model for the study of enzyme regulation in man. 567 20

Current hospital practice for testing renal function is to use the creatinine clearance test. Inulin clearance, an inherently more accurate procedure, currently is only carried out by specialized laboratories because there is not a simple biochemical assay for inulin, that is, an assay that could be carried out by any laboratory without special facilities. We have developed a simple enzymatic assay system for measuring inulin in plasma and urine. The procedure uses a beta-fructofuranosidase immobilized on Concanavalin A to convert inulin to fructose. Fructose is then measured by measuring the NADH----NAD conversion produced when fructose is converted to sorbitol by the enzyme sorbitol dehydrogenase. Kinetic parameters, binding capacities, and operating conditions for the immobilized beta-fructofuranosidase were determined as well as general operating parameters for the complete assay system. This system offers the potential for replacing the creatinine clearance test as the assay of choice for renal function.
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PMID:A simple inulin assay for renal clearance determination using an immobilized beta-fructofuranosidase. 659 2

A constitutive invertase (EC 3.2.1.26) was isolated and purified by the first time from Pycnoporus sanguineus. The enzyme is a glycoprotein. Its relative molecular mass is about 84,000 and its structure is dimeric, with two identical subunits (about 41,000). The enzyme is able to attack sucrose, raffinose, stachyose, inulin and levan, being sucrose the preferred substrate (Km 4.89 +/- 0.13 mM). Fructose was a classical competitive inhibitor, but glucose was not an inhibitor of the enzyme. Lectins with specificity toward glucose are inhibitors of the enzyme. Glucose was present in invertase acid hydrolysates. Unlike higher plant invertases, bovine serum albumin is not an effector of the Pycnoporus sanguineus enzyme, and the inhibition by fructose is not suppressed by this protein. The properties of the Pycnoporus sanguineus enzyme are discussed with reference to higher plant invertases.
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PMID:Purification and characterization of the invertase from Pycnoporus sanguineus. 766 14

To assess the effects of hypothyroidism (HT) on small-intestinal function, HT was induced in rats (120-150 g) by methimazole in drinking water. After 6 wk of methimazole, intestinal absorption studies were performed in HT and in control (C) rats by in situ luminal perfusion of a 20-cm proximal jejunal loop with a bicarbonate buffer containing sodium, glucose or fructose, glycine or lysine, and phenol red as a nonabsorbable marker for determination of water fluxes. Mucosa from the perfused segment was taken for assay of disaccharidases and ATPases and for light and electron microscopy. Compared with C rats, HT rats had significantly lower jejunal transport rates of water (2.54 +/- 0.36 versus 5.02 +/- 0.7 microL/min/microgram mucosal protein, p < 0.03), sodium (37.1 +/- 10.3 versus 102.7 +/- 18.6 mumol/min/microgram protein, p < 0.05), and glucose (1.49 +/- 0.28 versus 5.17 +/- 0.82 mumol/min/microgram protein, p < 0.02). A reduction in glycine transport was also observed but did not attain statistical significance (p = 0.058). Fructose and lysine transport was unchanged. Mucosal sucrase and lactase activities were similar in both groups, but Na,K-ATPase was significantly lower in HT rats (1.17 +/- 0.3 versus 4.03 +/- 1.5 mumol inorganic phosphate/h/mg protein; p < 0.05), with a diminution of ouabain binding sites by 41.5%. Light microscopy of jejunal mucosa from HT rats did not differ from that from C rats; electron microscopy showed mild mitochondrial swelling in HT enterocytes. A group of HT rats were treated with L-thyroxine during 4 wk; these rats had absorption rates, mucosal enzyme activities, ouabain binding, and mucosal morphology not different from C rats.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of hypothyroidism on jejunal mucosal function: study by in situ luminal perfusion in rats. 839 45

The facilitating effect of glucose on free fructose absorption has been suggested to be due to a sucrase-related transport mechanism. In contrast, the conditions influencing the absorption of sorbitol have hardly been investigated. As amino acids promote transcellular water flow, we investigated their effects on the absorption of fructose and sorbitol. We studied 15 healthy children using breath hydrogen tests following the ingestion of fructose and sorbitol, alone and in combination with glucose or amino acids. Similarly, the effect of acarbose pretreatment on sucrose and fructose-glucose absorption was investigated. The inhibition of sucrase isomaltase by acarbose impedes the absorption of sucrose but not of the fructose-glucose mixture. Fructose absorption is enhanced by glucose and by the amino acids L-alanine, L-glutamine, L-phenylalanine, and L-proline. Similarly, the absorption of sorbitol is facilitated by glucose and L-alanine. These results are not in concordance with a sucrase-related fructose-transport system and suggest another mechanism for glucose-induced enhancement of fructose (and sorbitol) absorption. We hypothesize that the absorption of fructose and sorbitol may be stimulated by the increased water flux induced by active absorption of glucose as well as amino acids.
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PMID:Facilitating effect of amino acids on fructose and sorbitol absorption in children. 885 76


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