• Journal of Microbiology and Biotechnology
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• v.17 no.5
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• pp.792-799
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• 2007

A gene encoding a putative glycogen-debranching enzyme in Sulfolobus shibatae(abbreviated as SSGDE) was cloned and expressed in Escherichia coli. The recombinant enzyme was purified to homogeneity by heat treatment and Ni-NTA affinity chromatography. The recombinant SSGDE was extremely thermostable, with an optimal temperature at $85^{\circ}C$. The enzyme had an optimum pH of 5.5 and was highly stable from pH 4.5 to 6.5. The substrate specificity of SSGDE suggested that it possesses characteristics of both amylo-1,6-glucosidase and $\alpha$-1,4-glucanotransferase. SSGDE clearly hydrolyzed pullulan to maltotriose, and $6-O-\alpha-maltosyl-\beta-cyclodextrin(G2-\beta-CD)$ to maltose and $\beta$-cyclodextrin. At the same time, SSGDE transferred maltooligosyl residues to the maltooligosaccharides employed, and maltosyl residues to $G2-\beta-CD$. The enzyme preferentially hydrolyzed amylopectin, followed in a decreasing order by glycogen, pullulan, and amylose. Therefore, the present results suggest that the glycogen-debranching enzyme from S. shibatae may have industrial application for the efficient debranching and modification of starch to dextrins at a high temperature.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.6 no.1
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• pp.15-23
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• 2006

Purpose: Glycogen storage disease type III (GSD-III), is a rare autosomal recessive disorder of glycogen metabolism. The affected enzyme is amylo-1,6-glucosidase, 4-alpha-glucanotransferase (AGL, glycogen debranching enzyme), which is responsible for the debranching of the glycogen molecule during catabolism. The disease has been demonstrated to show clinical and biochemical heterogeneity, reflecting the genotype-phenotype heterogeneity among different patients. In this study, we analyzed mutations of the AGL gene in three unrelated Korean GSD-III patients and discussed their clinical and laboratory implications. Methods: We studied three GSD-III patients and the clinical features were characterized. Sequence analysis of 35exons and part exon-intron boundaries of the AGLgene in patients were carried out by direct DNA sequencing method using genomic DNA isolated from patients' peripheral leukocytes. Results: The clinical features included hepatomegaly (in all patients), seizures (in patient 2), growth failure (in patients 1), hyperlipidemia (in patients 1 and 3), raised transaminases and creatinine kinase concentrations (in all patients) and mild EKG abnormalities (in patients 2). Liver transplantation was performed in patient 2due to progressive hepatic fibrosis. Administration of raw-corn-starch could maintain normoglycemia and improve the condition. DNA sequence analysis revealed mutations in 5 out of 6 alleles. Patient 1 was a compound heterozygote of c.1282 G>A (p.R428K) and c.1306delA (p.S603PfsX6), patient 2 with c.1510_1511insT (p.Y504LfsX10), and patient 3 with c.3416 T>C (p.L1139P) and c.l735+1 G>T (Y538_R578delfsX4) mutations. Except R428K mutation, 4 other mutations identified in3 patients were novel. Conclusion: GSD-III patients have variable phenotypic characteristics resembling GSD-Ia. The molecular defects in the AGL gene of Korean GSD-III patients were genetically heterogeneous.

• Journal of Dental Anesthesia and Pain Medicine
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• v.22 no.6
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• pp.451-455
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• 2022

Glycogen storage disease (GSD) is a group of inherited disorders, which result in the deficiency of enzymes involved in glycogen metabolism, leading to an accumulation of glycogen in various organs. Deficiency of amylo-1-6-glicosidase (debranching enzyme) causes glycogen storage disease type III (GSD III). The main problems that anesthesiologists face in patients with GSD III include hypoglycemia, muscle weakness, delayed awakening due to abnormal liver function, possible difficulty in airway, and cardiomyopathy. In the face of these difficulties, airway preparation and appropriate glucose monitoring and support during the fasting period are important. The doses of the drugs to be used should be calculated considering the increased volume of distribution and decreased metabolic activity of the liver. We present the case of a child with GSD IIIa who underwent dental prosedation under general anesthesia. She was also being prepared for liver transplantation. This case was additionally complicated by the patient's serious allergic reaction to eggs and milk.

• Journal of Genetic Medicine
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• v.4 no.1
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• pp.72-79
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• 2007

Purpose : Glycogen storage disease type III (GSD-III) is a rare autosomal recessive disorder of glycogen metabolism. The affected enzyme, amylo-1,6-glucosidase, 4-alpha-glucanotransferase (AGL, glycogen debranching enzyme), is responsible for the debranching of the glycogen molecule during catabolism. The disease shows clinical and biochemical heterogeneity, reflecting genotype-phenotype heterogeneity among different patients. In this study, we aim at analyzing mutations of the AGL gene in three unrelated Korean GSD-III patients, and characterizing their clinical and laboratory findings. Methods : We characterized the clinical features of three unrelated Korean GSD-III patients by biochemical, histological and imaging studies. The 35 exons and part of exon-intron boundaries of AGL were analyzed by direct sequencing using genomic DNA extracted from the peripheral leukocytes of patients. Results : Diverse clinical features were observed in these patients including hepatomegaly (all patients), seizures (patient 2), grow th failure (patients 1 and 2), hyperlipidemia (patients 1 and 3), raised transaminase and creatine kinase concentrations (all patients), and mild cardiomyopathy (patient 2). Liver transplantation w as performed in patient 2 due to progressive hepatic fibrosis. A dministration of uncooked corn starch maintained normoglycemia and improved biochemical and growth profiles. DNA sequence analysis revealed mutations in 5 out of 6 alleles. Patient 1 was a compound heterozygote of c.1282 G>A (p.R428K) and c.1306delA (p.S603PfsX6), patient 2 had c.1510_1511insT (p.Y 504L fsX 10), and patient 3 had c.3416 T >C (p.L 1139P) and c.1735+1 G>T (p.Y 538_R578delfsX 4) mutations. A part from the p.R428K mutation, the 4 other substitutions identified w ere nov el. Conclusion : GSD-III patients display variable phenotypic characteristics resembling those of GSD-Ia. Molecular defects in the AGL gene of Korean GSD-III patients are genetically heterogeneous.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.12 no.2
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• pp.108-112
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• 2012

Glycogen storage disease type III (GSD type III, OMIM #232400) is a rare autosomal recessive disease caused by a deficiency of the glycogen-debranching enzyme (GDE) with a mutation in the AGL gene (OMIM *610860). It is known to be bifunctional enzyme, that is, having two independent catalytic activities; 1,4-${\alpha}$-D-glucan 4-${\alpha}$-D-glycosyltransferase (EC 2.4.1.25) and amylo-1,6-glucosidase (EC 3.2.1.33) that occur at separate active sites on a single polypeptide chain. Most patients with GSD type III usually have symptoms related to decreased glycogenolysis in liver and muscles, such as hepatomegaly, hypoglycemia, failure to thrive, hyperlipidemia, muscle weakness and cardiomyopathy (type IIIa), however some patients show symptoms restricted to liver (type IIIb). GSD type III is diagnosed by enzyme test through liver or muscle biopsy or mutation analysis of the AGL gene. We report the case of GSD type III proven by gene study after liver biopsy, which revealed c.476delA, c.3444_3445insA in exon 6, 27 of AGL gene in Korean patient.

• Journal of Microbiology and Biotechnology
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• v.29 no.3
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• pp.357-366
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• 2019

We first confirmed the involvement of MalQ (4-${\alpha}$-glucanotransferase) in Escherichia coli glycogen breakdown by both in vitro and in vivo assays. In vivo tests of the knock-out mutant, ${\Delta}malQ$, showed that glycogen slowly decreased after the stationary phase compared to the wild-type strain, indicating the involvement of MalQ in glycogen degradation. In vitro assays incubated glycogen-mimic substrate, branched cyclodextrin (maltotetraosyl-${\beta}$-CD: G4-${\beta}$-CD) and glycogen phosphorylase (GlgP)-limit dextrin with a set of variable combinations of E. coli enzymes, including GlgX (debranching enzyme), MalP (maltodextrin phosphorylase), GlgP and MalQ. In the absence of GlgP, the reaction of MalP, GlgX and MalQ on substrates produced glucose-1-P (glc-1-P) 3-fold faster than without MalQ. The results revealed that MalQ led to disproportionate G4 released from GlgP-limit dextrin to another acceptor, G4, which is phosphorylated by MalP. In contrast, in the absence of MalP, the reaction of GlgX, GlgP and MalQ resulted in a 1.6-fold increased production of glc-1-P than without MalQ. The result indicated that the G4-branch chains of GlgP-limit dextrin are released by GlgX hydrolysis, and then MalQ transfers the resultant G4 either to another branch chain or another G4 that can immediately be phosphorylated into glc-1-P by GlgP. Thus, we propose a model of two possible MalQ-involved pathways in glycogen degradation. The operon structure of MalP-defecting enterobacteria strongly supports the involvement of MalQ and GlgP as alternative pathways in glycogen degradation.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.20 no.1
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• pp.24-28
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• 2020

Type III Glycogen storage disease (Type III GSD, OMIM#232400) is a genetic metabolic disorder in which undigested glycogen accumulates in the organs due to lack of glycogen debranching enzyme caused by AGL mutation. The clinical symptoms of type III GSD include hepatomegaly, delayed growth, hypoglycemia and muscle weakness. These clinical symptoms are similar to those of other types of GSD, making it difficult to distinguish clinically. The authors report a case of type III GSD diagnosed by gene panel sequencing. A 11-month old male patient was presented with hepatomegaly. In liver biopsy, glycogen was accumulated in hepatocytes, suggesting GSDs. For differential diagnosis of types of GSD, gene panel sequencing for GSDs was performed. As a result, two novel pathogenic compound heterozygous variants: c.311_312del (p.His104Argfs*15) and c.3314+1G>A in AGL were detected and the patient was diagnosed as type III GSD. After diagnosis, he started dietary treatment with cornstarch, and has been free from complications. After two years, two same variants were also identified in the chorionic villous sampling of the pregnant mother, and the fetus was diagnosed as type III GSD. Gene panel sequencing is useful for diagnosis of disease which is indistinguishable by clinically and has high genetic heterogeneity, such as GSD. After diagnosis, familial genetic analysis can provide adequate genetic counseling and rapid diagnosis.