Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.20 (alpha-glucosidase)
 4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Each of 12 types of glycogen storage disease (GSD O-XI) is delineated by clinical, biochemical and histologic features that allow its identification in future patients. GSD II occurs in 2 forms that are not both encountered in the same family. GSD IIa is the infantile fatal form with cardiomegaly, increased cardiac glycogen concentration and cardiac failure; GSD IIb is the adult form with clinically normal heart and normal cardiac glycogen concentration. Nonetheless, the heart muscle of both forms is equally deficient in acid alpha-glucosidase activity, and this raises questions as to the latter's role in the pathophysiology of GSD II. The appearance of hepatocytes in GSD IIa becomes normal after the administration of alpha-glucosidase. Using electron microscopy of uncultured amniotic fluid cells, the prenatal diagnosis of GSD IIa is feasible within one day after the amniocentesis. GSD VI and IX are instances of benign hepatomegaly except when GSD IX and III occur in the same child; one such patient died suddenly at home. There are 2 modes of inheritance in GSD IX: one (GSD IXa) is autosomal recessive, the other one (GSD IXb) is X-linked recessive. In either form the Km of the remaining liver phosphorylase kinase is normal. Both forms of GSD IX have the normal blood sugar response to glucagon, whereas GSD VI does not. Equally, the glucagon tolerance curve is flat in GSD XI although in vitro activity of glycolytic enzymes is normal. The in vivo administration of glucagon in GSD XI is followed by the normal increase of both urinary 3'5'-AMP and hepatic phosphorylase activity. GSD V may have increased activity of muscle phosphorylase kinase. Deficiencies of debrancher, liver phosphorylase and liver phosphorylase kinase can occur singly or in combination. Before any novel treatment of GSD is initiated, one should obtain tissue for the biochemical determination of the exact type of GSD. This is so because the clinical signs may not indicate the type with the necessary precision, and because some types are compatible with normal life and thus may not require therapy, especially if the latter is unproved and potentially dangerous.
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PMID:Glycogen storage diseases. 78 7

Three forms of alpha-glucosidase were separable in trout liver by DE-52 chromatography, isoelectrofocusing, and gel filtration. Two forms showed acid pH optima, hydrolyzed glycogen, maltose, and 4-methylumbelliferyl alpha-glucoside, and were associated with the lysosomes. The third enzyme form was largely associated with microsomes and was present in the highest activity; it showed a neutral pH optimum and did not hydrolyze glycogen. Molecular weights were 181 +/- 2, 130 +/- 1.5, and 365 +/- 3 kDa for the acid types I and II and the neutral enzyme, respectively. Maximal activities and kinetic and physical properties of the three enzymes were compared in liver samples from control, resting fish versus fish that underwent exhaustive swimming exercise. The properties of liver acid alpha-glucosidase type I changed significantly in response to exercise; maximal activity increased by 80% and Km values for both glycogen and maltose dropped by 50% in exercised, versus control, fish. Under the same exercise condition, liver glycogen phosphorylase a activity also increased 4.4-fold. These changes in alpha-glucosidase type I are consistent with an activation of the enzyme, in parallel with phosphorylase activation, under physiological stress conditions that promote glycogenolysis and glucose export from liver. These results are, we believe, the first demonstration of the activation of the glucosidic route of glycogenolysis in response to a physiological stress and suggest that the glucosidic route has a significant role to play in complementing the phosphorolytic pathway in the metabolic response by liver to the fuel demands of working muscle.
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PMID:Characterization of alpha-glucosidases from rainbow trout liver. 821 2