Lysosomal glucosidase

Type II (Pompe s) Lysosomal glucosidase Skeletal and cardiac muscle Infantile form death by age 2 juvenile form muscle defects (myopathy) adult form as in muscular dystrophy... 

Some degradation of glycogen also occurs within lysosomes when glycogen particles become surrounded by membranes that then fuse with the lysosomal membranes. A lysosomal glucosidase hydrolyzes this glycogen to glucose. 

Vercauteren et al that the in vitro degradation of dextrans in the presence of lysosomal glucosidases or endodextranases is rather slow. Moreover, it was shown that chemical modification of the dextran further reduces its biodegrad-ability. ... 

Type II (Pompe s diseasel Insufficient levels of the enzyme lysosomal glucosidase. Massive glycogen infiltration particulariy of the heart cardiac distress been failure. Treatment is useless. 

The only other examples of bromoconduritol inhibition reported so far are a cytosolic jff-D-glucosidase from calf liver and the lysosomal ff-D-glu-cosidase from calf spleen. In spite of the 6500-fold difference in their reactivity with conduritol B epoxide (see Table XI), both enzymes are rapidly inactivated by bromoconduritol F, with kj(max)/Kj 10 M min for the cytosolic enzyme and lq(max)/Ki 3.2 10 for the crude and 3.9 10 M min for the purified lysosomal enzyme. It should be noted that purification of the lysosomal jS-D-glucosidase had effects on the reactivity with bromoconduritol F similar to those it had on the reactivity with conduritol B epoxide (see Table XI). 

V al-Met-Ser-Asp-T rp-Ala-Ala-His-His-Ala-Gly-Val-)S-D-Glucosidase A (bitter almonds) lle-Thr-Glx-Glx-Val-Phe-Gly-Asp-Ser-(Ala, Asxj, Glx, Pro)-Lys ff-D-Glucosidase (human placenta, lysosomal) -Val-Ala-Ser-Gln-Lys-Asn-Asp-Leu-Asp-Ala-Val-Ala-a-D-Glucosidase (sucrase, rabbit small intestine) -lle-Asp-Met-Asn-Glu-Pro-Asn-a-D-Glucosidase (isomaltase, rabbit small intestine) -Gly-Gly-Gln-lle-Asp-Met-)ff-D-Galactosidase (Escherichia co//) -Ser-Leu-Gly-Asn-Glu-Ser-Gly-His-Gly-Ala-... 

II Pompe Lysosomal a- 1,4-glucosidase Cardiomegaly, muscle weakness, death by 2 years Glycogen-like material in inclusion bodies... 

V. Patel and A. L. Tappel, Identity of P-glucosidase and P-xylosidase activities in rat liver lysosomes, Biochim. Biophys. Acta Enzymol., 191 (1969) 653-662. 

Pyruvate kinase-muscle isozyme Muscle-specific phosphorylase kinase Lysosomal acid a-glucosidase... 

Storage and pipetting of a-glucosidase should be carried out separately from all other lysosomal enzymes to avoid contamination of microtiter plates and pipettes. 

TYPE II POMPE DISEASE (LYSOSOMAL a(1 ->4 )-GLUCOSIDASE DEFICIENCY) ... 

The most serious of the storage diseases involve none of the enzymes mentioned above. Pompe disease is a fatal generalized glycogen storage disease in which a lysosomal a-l,4-glucosidase is lacking. 

Lysosomal a-glucosidase (Type II) Lethal, infant and adult form... 

Pauly, D. F., Johns, D. C., Matelis, L. A., Lawrence, J. H., Byrne, B. J. and Kessler, P. D. (1998). Complete correction of acid alpha-glucosidase deficiency in Pompe disease fibroblasts in vitro, and lysosomally targeted expression in neonatal rat cardiac and skeletal muscle. Gene Ther. 5, 473-480. 

---