Amylo-l,6-glucosidases

Glycogen metabolism disorders Amylo-l,6-glucosidase defect Liver phosphorylase defect Glycogen synthetase defect... 

Incorporation of [14C]-glucose into glycogen by the reverse reaction of the hydrolase amylo-l,6-glucosidase. Measurement of the incorporated radioactivity in the precipitated glycogen [20, 39]. This assay can only test the enzymes function of the hydrolysis of the 1-6 bond (see section 4.6.16.1). 

Amylo-l,6-Glucosidase (Debranching Enzyme, EC 3.2.1.33), Assay with [14C]-Glucose... 

In GSD IX (phosphorylase b-kinase deficiency), amylo-l,6-glucosidase activity in RBC is usually elevated. 

Amylo-l,6-glucosidase is the enzyme deficient in glycogenosis type III (GSD III, MIM 232 400). 

Table 4.6.13 Enzyme activities (amylo-l,6-glucosidase - as assessed by levels of phosphorylase limit dextrin, PLD, and glycogen) in RBC... 

Brown DH, Brown BI (1966) Enzymes of glycogen debranching amylo-l,6-glucosidase and oligo-l,4->l,4-glucantransferase. Methods Enzymol 8 515-524... 

Van Hoof F (1967) Amylo-l,6-glucosidase activity and normal glycogen content of the erythrocytes of normal subjects, patients with glycogen storage disease and heterozygotes. Eur J Biochem 2 271-274... 

Amylo-l,6-glucosidase, or dextrin-1,6-glucosidase Dextrin 6-glucanohydrolase 3.2.1.33... 

In the method of Cori and Lamer, glycogen (or amylopectin) is completely digested by the concurrent action of muscle phosphorylase and amylo-(l 6)-glucosidase. n-Glucose (which arises only from residues attached to C6 of an adjacent residue) and n-glucosyl phosphate (which is obtained from all other residues) are determined, and the branch-point content is calculated from the proportion of D-glucose. Only 10-15 mg. of glycogen is required for each assay the method has been applied to more... 

Since the yield of n-glucose released from a -dextrin by amylo-(l — 6)-glucosidase is dependent on the proportion of A-chains, the above method can be used to determine A. B. recorded in Table V are typical results which have been calculated from the experimental data of (jlerty T. Cori and coworkers on the assumption that debranching of the < -limit dextrin was complete. 

Fig. 6.—Interconversion of Glycogen and n-Glucose by way of Glycogen Cycle. (Key (1), hexokinase-adenosine 5-triphospliate (2), phosphoglucomutaae (3),UDPG-pyrophoaphorylase (4), glycogen-UDPglucosyl transferase and branching enzyme (5), phosphorylase and amylo-l,6-glucosidase (6), D-glucose 6-phosphatase.)...

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