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Abstract
α-Glucosidase (EC 3.2.1.20) catalyzes the hydrolysis of α-glucosidic linkages at the non-reducing end of substrates to liberate α-D-glucose (Nisizawa and Hashimoto, 1970). This enzyme is widely distributed in various organisms including bacteria, yeasts, fungi, archaea, plants, and animals (Kobayashi et al., 2015). The substrate specificity of α-glucosidases varies depending on the enzyme origin. α-Glucosidases are classified into three groups based on substrate specificity. group I, enzymes prefer heterogeneous substrates, represented by sucrose and synthetic glucosides, including p-nitrophenyl α-D-glucopyranoside (pNPG) and phenyl α-D-glucopyranoside, to homogeneous substrates such as maltose, whereas group II, enzymes prefer homogeneous substrates to heterogeneous substrates. Additionally, group III, enzymes are highly active toward homogeneous long-chain substrates such as starch (Chiba, 1988).
The gene coding for human lysosomal α-glucosidase (Acid α–glucosidase) is about 20 kb long and its structure has been cloned and confirmed. This gene encodes lysosomal α-glucosidase, which is essential for the degradation of glycogen to glucose in lysosomes. The encoded preproprotein is proteolytically processed to generate multiple intermediate forms and the mature form of the enzyme. Defects in this gene are the cause of glycogen storage disease II, also known as Pompe’s disease, which is an autosomal recessive disorder with a broad clinical spectrum resulying in accumulation of glycogen in lysosomes (O’leary et al., 2016).
The incidence of Pompe’s disease is estimated to be 1:40,000 but may vary in different ethnic populations (Jae-Wan Jung et al., 2016). Research has shown that Pompe’s disease is pan-ethnic—it occurs in people of all ethnicities and races. In infants, the disease has a higher frequency among African-Americans and people from southern China and Taiwan (Hirschhorn et al., 2001). Among adults, the disease has a higher frequency in the Netherlands (Ausems et al., 1999).