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)

Glycogen-storage disease type II, Pompe disease, is caused by the deficiency of acid alpha-D-glucosidase in lysosome. Previously we found that acid alpha-D-glucosidase did exist in the skin fibroblasts and there was also no difference of mRNA in quantity and size of Chinese infantile type Pompe disease patients in Taiwan. However, functional assay of the acid alpha-D-glucosidase of these patients showed its enzyme function to be defective. In the present study, first we identified a substitution site in four Chinese infantile patients with Pompe disease which is a cytidine to adenosine (C1935-->A) transversion at 5' end of exon 14 causing substitution of glutamic acid for aspartic acid at position 645 of the acid alpha-D-glucosidase. This substitution was introduced in wild-type cDNA and expressed in COS-1 cells. The Asp-645-->Glu substitution resulted in significant reduction of acid alpha-D-glucosidase activity. Second, according to the screening data in 25 Chinese Pompe disease patients using digestion of RT-PCR amplified specific fragment with Aat II, the restriction fragment length analysis showed that patients presented the 861 bp band and the normal individuals presented the 728 bp and 133 bp polymorphic bands. We found that the frequency of mutant allele is 0.8 in infantile patients with Chinese Pompe disease and 0 in normal individuals. These results therefore indicate that Asp-645-->Glu mutation results in infantile form of Pompe disease as the major cause in Chinese patients in Taiwan.
 ...
PMID:Molecular study on the infantile form of Pompe disease in Chinese in Taiwan. 893 10

The mechanism-based reagent 5-fluoro-alpha-d-glucopyranosyl fluoride (5F alpha GlcF) was used to trap a glycosyl-enzyme intermediate and identify the catalytic nucleophile at the active site of Aspergillus niger alpha-glucosidase (Family 31). Incubation of the enzyme with 5F alpha GlcF, followed by peptic proteolysis and comparative liquid chromatography/MS mapping allowed the isolation of a labelled peptide. Fragmentation analysis of this peptide by tandem MS yielded the sequence WYDMSE, with the label located on the aspartic acid residue (D). Comparison with the known protein sequence identified the labelled amino acid as Asp-224 of the P2 subunit.
 ...
PMID:Identification of the catalytic nucleophile of the Family 31 alpha-glucosidase from Aspergillus niger via trapping of a 5-fluoroglycosyl-enzyme intermediate. 1158 85

Brush-border maltase-glucoamylase (MGA) activity serves as the final step of small intestinal digestion of linear regions of dietary starch to glucose. Brush-border sucrase-isomaltase (SI) activity is complementary, through digestion of branched starch linkages. Here we report the cloning and sequencing of human MGA gene and demonstrate its close evolutionary relationship to SI. The gene is approximately 82,000 bp long and located at chromosome 7q34. Forty-eight exons were identified. The 5' gene product, when expressed as the N-terminal protein sequence, hydrolyzes maltose and starch, but not sucrose, and is thus distinct from SI. The catalytic residue was identified by mutation of an aspartic acid and was found to be identical with that described for SI. The exon structures of MGA and SI were identical. This homology of genomic structure is even more impressive than the previously reported 59% amino acid sequence identity. The shared exon structures and peptide domains, including proton donors, suggest that MGA and SI evolved by duplication of an ancestral gene, which itself had already undergone tandem gene duplication. The complementary human enzyme activities allow digestion of the starches of plant origin that make up two-thirds of most diets.
 ...
PMID:The maltase-glucoamylase gene: common ancestry to sucrase-isomaltase with complementary starch digestion activities. 1254 8