Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.20 (alpha-glucosidase)
4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

AO-128 is a potent and structurally novel inhibitor of the intestinal disaccharidases, such as maltase and sucrase. Genetically obese-diabetic mice, KKA(y), were used to examine the acute or long-term effectiveness of this compound. AO-128 decreased a postprandial rise in blood glucose after sucrose solution loading dose-dependently; the ED50 to reduce a delta increment of blood glucose by 50% was 0.22 mg/kg. The intestinal sucrase and maltase activities were suppressed to 7 and 48% of the control levels, respectively, at a dose of 0.21 mg/kg. Four-week-old female KKA(y) mice were kept on a laboratory diet containing 10 or 50 ppm of AO-128 for 12 weeks. The high dose of AO-128 reduced food intake and body weight gain throughout the experimental period. On the other hand, the low dose reduced body weight gain for the first 4 weeks without any effect on food intake. Development of the hyperglycemia and hyperinsulinemia characteristic of KKA(y) mice was moderately prevented by the low dose, and completely by the high dose. Hypertriglyceridemia tended to be suppressed by the AO-128 treatment. The high dose decreased the hemoglobin A1 level and parametrial adipose tissue weight. Hepatomegaly and fatty liver were ameliorated by AO-128 dose-dependently. Nephropathy was ameliorated by the high dose. These findings indicate that AO-128 may be useful for treating human obesity and diabetes.
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PMID:Antiobesity and antidiabetic actions of a new potent disaccharidase inhibitor in genetically obese-diabetic mice, KKA(y). 162 84

Adler and Martin (1983, Curr. Eye Res. 2, 359-66) found cathepsin D to be present in crude preparations of bovine interphotoreceptor matrix (IPM). The purpose of the present study was to determine, by investigating several acid hydrolases in purer IPM samples, whether hydrolytic enzymes abundant in RPE lysosomes were present also as normal components of the IPM. IPM was prepared from bovine eyes by the introduction of a small bleb of buffer between the neural retina and the RPE. These IPM samples were free from significant contamination by surrounding tissues; they contained IRBP as their only major protein, and had negligible amounts of lactate dehydrogenase and ROS-specific proteins. Most acid hydrolases were assayed fluorometrically by measuring the 4-methylumbelliferone released upon hydrolysis of appropriate derivatives; the substrate for cathepsin was hemoglobin. The amounts of the enzymes found in the IPM were far from uniform and could not be correlated with enzyme activities in either RPE or retina homogenates. The hydrolases in the IPM varied in amount from beta-galactosidase (28% of the RPE level), through N-acetyl-beta-glucosaminidase (20%), alpha-fucosidase (15%), beta-glucuronidase (12%), alpha-glucosidase (8%), cathepsin D (7%), alpha-mannosidase (7%), down to beta-glucosidase, acid phosphatase, and acid lipase (trace amounts, less than 1%). These results agree with the relative amounts of enzymes found by Wilcox (1987) to be secreted into the medium by cultured human RPE cells. Furthermore, the rank order of hydrolases in the IPM is the same as that for hydrolases secreted (but not recaptured) by human fibroblasts in I-cell disease. The conclusion from these correlations is that lysosomal enzymes are probably secreted, as a normal process, by the RPE into the IPM, where they may have a role in digesting shed outer segments and in catabolizing IPM components.
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PMID:Selective presence of acid hydrolases in the interphotoreceptor matrix. 261 85

Miglitol (BAYm 1099), an alpha-glucosidase inhibitor, reduces the postprandial increase of blood glucose and serum insulin levels in type II (non-insulin-dependent) diabetes mellitus, as shown in short-term studies. In this study, the effects of long-term miglitol treatment on metabolic control, C-peptide secretion, hepatic glucose output, and peripheral insulin sensitivity (euglycemic clamp) were tested in 15 type II diabetic patients (8 receiving insulin, 7 receiving oral hypoglycemic agents). For 8 wk they received either miglitol (300 mg/day) or placebo with a double-blind crossover design that had a 4-wk washout period between treatments. Miglitol therapy induced a reduction of postprandial blood glucose levels (miglitol compared with placebo; areas under the curve; P less than .002), whereas fasting blood glucose levels were not influenced. Miglitol caused a slight reduction of glycosylated hemoglobin levels (mean +/- SE miglitol and placebo 9.50 +/- 0.3 and 10.0 +/- 0.4%, respectively; P less than .05), which was more pronounced in insulin-treated patients. Miglitol caused a reduction of postprandial C-peptide increase (P less than .03). Hepatic glucose output (both in the basal state and during euglycemic clamp conditions) and peripheral insulin sensitivity were not influenced by miglitol therapy. Specific side effects were observed in 11 patients; in 6 patients only to a moderate degree. Long-term miglitol treatment induces a persistent reduction of postprandial blood glucose increase. This effect is more pronounced in type II diabetic patients on insulin therapy, which can cause a moderate improvement of overall metabolic control.
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PMID:Effects of 8-wk alpha-glucosidase inhibition on metabolic control, C-peptide secretion, hepatic glucose output, and peripheral insulin sensitivity in poorly controlled type II diabetic patients. 267 93

A new chromogenic substrate that is blocked at the nonreducing end, 4,6-benzylidene-alpha-D-4-nitrophenylmaltoheptaoside, is used to determine alpha-amylase (EC 3.2.1.1) activity in serum in a coupled assay with alpha-glucosidase (EC 3.2.1.20) and glucoamylase (EC 3.2.1.3) as auxiliary enzymes. The duration of the lag phase between 25 and 37 degrees C is less than 90 s, and the molar absorptivity of 4-nitrophenol is constant. The main cleavage product of the substrate by human pancreatic and salivary alpha-amylase is 4-nitrophenylmaltoside; in the presence of the auxiliary enzymes, greater than 95% of hydrolyzed substrate is accounted for as 4-nitrophenol. The combined reagent is stable for at least 20 days at 2-8 degrees C; precision is good, with CVs ranging from 1.7 to 3.3%; and the correlation of results with those by the 4-nitrophenylmaltoheptaoside method is excellent. Heparin (40 kilo-int. units/L), ascorbic acid (2.8 mmol/L), bilirubin (430 mumol/L), hemoglobin (170 mumol/L), glucose (55 mmol/L), and triglycerides (11 mmol/L) do not interfere in the assay.
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PMID:Rapid determination of alpha-amylase activity by use of a new chromogenic substrate. 310 53

Homogenates of Giardia lamblia trophozoites exhibited the following hydrolase activities: acid phosphatase (EC 3.1.3.2), proteinase (EC 3.1.4) with urea-denatured hemoglobin and N-benzoyl-DL-arginine-2-naphthylamide as substrates, deoxyribonuclease (EC 3.1.4.5), and ribonuclease (EC 2.7.7.16). beta-N-Acetylglucosaminidase (EC 3.2.1.30), beta-galactosidase (EC 3.2.1.23), beta-glucuronidase (EC 3.2.1.31), alpha-D-glucosidase (EC 3.2.1.20), beta-D-glucosidase (EC 3.2.1.21), and beta-D-xylosidase (EC 3.2.1.37) activities were below the level of detection. Differential and isopycnic centrifugation of homogenates demonstrated that giardial hydrolases were localized in a single-particle population sedimenting at 7200g for 30 min. The particles had a buoyant density in sucrose of 1.15 and exhibited latency. Latency was completely destroyed by Triton X-100 or 15 cycles of freezing and thawing. After centrifugation of Triton- or freeze-thaw-treated particle fractions, the hydrolase activities, though no longer latent, were still sedimentable suggesting tight binding to the organelle membrane. Latency was destroyed simultaneously for all hydrolases, in direct proportion to the amount of Triton added to a particle preparation or to the number of times a particle preparation was subjected to freezing and thawing. These results support the suggestion that the hydrolases of G. lamblia trophozoites are localized in a single-particle population of lysosome-like organelles.
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PMID:Giardia lamblia: localization of hydrolase activities in lysosome-like organelles of trophozoites. 327 50

Several lysosomal enzymes (beta-N-D-acetylglucosaminidase, beta-D-glucuronidase, alpha-D-galactosidase, beta-D-galactosidase, alpha-L-fucosidase, alpha-D-glucosidase, alpha-D-mannosidase, beta-D-glucosidase), glycated albumin and glycated hemoglobin (HbA1c) were determined in the serum of 81 insulin-dependent diabetics with different degrees of metabolic control (optimal, 21 patients; good, 39 patients; poor, 21 patients) and without signs of complications, and in 42 control subjects. All parameters examined increased in serum in inverse proportion to the degree of metabolic control. A highly significant correlation (p less than 0.01) was found between lysosomal enzymes and both glycated albumin and HbA1c. All parameters correlated with hyperglycemia, glycated albumin having the highest r-value (0.586) and lysosomal enzymes the lowest one. Unlike glycated albumin and HbA1c, serum levels of lysosomal enzymes in patients with optimal metabolic control were undistinguishable or even lower than those of controls. A 2-month longitudinal monitoring of a patient who was hospitalized in conditions of poor metabolic control and adequately treated, proved that lysosomal enzymes diminished in serum parallel to glycated albumin and HbA1c in relation to improvement of the metabolic situation. The conclusion is drawn that serum lysosomal enzymes are good indicators of the metabolic control of diabetic patients probably reflecting the overall metabolic state connected with insulin action rather than hyperglycemia.
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PMID:Serum enzymes of lysosomal origin as indicators of the metabolic control in diabetes: comparison with glycated hemoglobin and albumin. 375 46

We describe a method for measuring the catalytic activity of alpha-amylase (EC 3.2.1.1) in serum and urine, by use of a defined substrate: 1,4-alpha, D-4-nitrophenyl maltoheptaoside. We use a phosphate buffer of pH 7.10, containing chloride as activator and alpha-glucosidase (EC 3.2.1.20) as the auxiliary enzyme. After a lag phase of 4 min at 25 degrees C or 30 degrees C, or 3 min at 37 degrees C, the increase of absorption of 4-nitrophenol is measured at 410 nm or 405 nm. The pH value of the assay mixture is a compromise between optimum pH for the alpha-amylase reaction, shortest possible lag phase, and an acceptable absorptivity of 4-nitrophenol. Because the dissociation of 4-nitrophenol depends strongly on pH and temperature, we determined its absorptivity with various combinations of these variables in the assay. Heparin-treated plasma can be used, but not EDTA, fluoride, or citrate. Lipemia, hemoglobin less than or equal to mumol/L, bilirubin less than or equal to 170 mumol/L, glucose less than or equal to 100 mmol/L, and ascorbic acid less than or equal to 1 mmol/L of sample do not interfere in the assay.
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PMID:Optimized conditions for determining activity concentration of alpha-amylase in serum, with 1,4-alpha-D-4-nitrophenylmaltoheptaoside as substrate. 387 Nov 78

We tested a new amylase reagent involving chromogenic substrates (Pantrak, Calbiochem-Behring) for precision, dynamic range, and susceptibility to potential interferences. Two p-nitrophenyl-alpha-maltaosides are used as substrates, which amylase cleaves to shorter-chain p-nitrophenyl maltaosides, the latter then yielding p-nitrophenol from the activity of alpha-glucosidase. A series of 100 specimens were tested by Pantrak and two established methodologies. In both cases, correlation was excellent. Precision was good for all methods; CVs for Pantrak were 3.0 to 4.5%. The dynamic range of Pantrak extended to 800 U/L. Above-normal quantities of triglyceride, hemoglobin, or bilirubin did not cause spurious results, but anticoagulants that bind divalent cations should not be used. The Pantrak method has desirable analytical features and is easy to use.
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PMID:A new chromogenic amylase method compared with two established methods. 617 60

Recent investigations point to the nonenzymatic glycosylation as a cause of long-term complications in diabetes mellitus. We describe an enzymatic activity that cleaves glucose from the glomerular basement membrane (GBM), present in lysosomal preparations of diabetic lymphocytes. The GBM, nonenzymatically glycosylated or obtained from rats with diabetes, were incubated with enzyme preparations, separated on Sephadex G-25 and applied for glucose measurement on gas chromatography and mass spectroscopy. The lysosomal preparation of diabetic lymphocytes cleaved from rat GBM, which were nonenzymatically glycosylated 300-500 ng glucose/mg GBM protein, from diabetic rat GBM 300 ng glucose/mg GBM protein. A lysosomal preparation of normal lymphocytes failed to do so, indicating enzyme induction in the diabetic state. Control studies with the glycosylated hemoglobin AIc confirmed this finding and showed the specificity of the enzyme, as alpha-glucosidase and beta-glucosidase failed to cleave the N-glycosidic bond between glucose and the protein. The enzymatic activity can be described formally as a N-l-deoxyfructofuranosyl-glucohydrolase, which could be responsible for a potential reversibility of diabetic GBM changes.
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PMID:Enzymatic reversibility of nonenzymatic glycosylation of the glomerular basement membrane. Is the diabetic glomerulopathy principally reversible? 683 51

Newborn rats born to iron deficient mothers (IDM) were found to have significantly lower hemoglobin, sucrase, lactase and maltase levels compared to control newborn rats. Rats born to IDM and nursed by IDM, when sacrificed at 21 days of age, had statistically significantly lower hemoglobin, serum iron, sucrase, lactase and maltase levels compared to control rats. Rats born to IDM, but nursed by iron sufficient mothers (ISM) and sacrificed at 21 days of age, had hemoglobin, serum iron and sucrase levels compared to control rats whereas lactase and maltase were not corrected by 21 days of nursing by ISM. Rats burn to IDM and nursed by either IDM or ISM for 21 days were given intramuscular iron dextran and placed on iron sufficient diet (ISD) for 7 days. These animals experienced correction of the hemoglobin, serum iron, sucrase and maltase levels compared to control rats, whereas intestinal lactase was not corrected by 7 days of ISD and intramuscular iron. Rats born to ISM, nursed by IDM and sacrificed on day 21 had significantly lower hemoglobin, serum iron and intestinal lactase levels compared to control rats. Rats both to ISM and nursed by IDM were given intramuscular iron dextran on day 21 and placed on an ISD from day 21-28. These animals had a return in hemoglobin, serum iron, sucrase and maltase levels comparable to control rats. Rats born to and nursed by ISM and maintained on an iron deficient diet from day 21-84 had significantly lower hemoglobin, serum iron, sucrase, lactase and maltase levels compared to control rats. Rats born to and nursed by ISM, maintained on iron deficient diet from day 21-84, and then given intramuscular iron dextran on day 84 and maintained on an ISD until day 92, experienced correction of the hemoglobin, serum iron and lactase levels compared to control rats. Intramuscular iron and 7 days of ISD did not correct the sucrase and maltase levels in these rats. Lactose tolerance tests in iron deficient rats showed flat curves compared to controls. After iron treatment, lactose tolerance curves returned to control values. Iron deficiency in rats in utero, during the nursing and postweaning period causes, in addition to anemia, a reduction in jejunal disaccharidase activity because of an alteration in the enzymes of the brush border membrane. Varying degrees of reduction and response of certain disaccharidases to iron treatment are dependent on the time of iron deprivation in relationship to the intra-uterine and postnatal development of the digestive and absorptive functions in the small intestine. Alterations in the levels of disaccharidases demonstrated in this paper represents another aspect of the spectrum of biochemical effects of iron deficiency.
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PMID:Disaccharidase levels in iron deficient rats at birth and during the nursing and postweaning periods: response to iron treatment. 707 2


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