Glucan 1,4-alpha-glucosidase (GAA/MGAM)

Glucan 1,4-alpha-glucosidase (EC 3.2.1.3) is a glycoside hydrolase enzyme that catalyzes the hydrolysis of terminal 1,4-linked alpha-D-glucose residues from the non-reducing ends of polysaccharides [1, 2]. In humans, this enzymatic activity is primarily associated with two major therapeutic targets: the lysosomal enzyme acid alpha-glucosidase (GAA) and the intestinal brush border enzyme maltase-glucoamylase (MGAM) [12, 13]. GAA is critical for the degradation of glycogen within lysosomes; its deficiency leads to Pompe disease (glycogen storage disease type II), a progressive and often fatal neuromuscular disorder characterized by glycogen accumulation in cardiac and skeletal muscles [12, 14]. MGAM, along with sucrase-isomaltase, is responsible for the final stages of starch digestion in the small intestine [1, 16]. Therapeutically, GAA is targeted through enzyme replacement therapies (ERT), such as alglucosidase alfa and avalglucosidase alfa, which aim to clear lysosomal glycogen and improve motor and respiratory function in Pompe disease patients [12, 15]. Conversely, intestinal alpha-glucosidases like MGAM are targeted by inhibitors such as acarbose and miglitol to manage type 2 diabetes [5, 16]. These drugs competitively inhibit the enzyme, thereby slowing the conversion of complex carbohydrates into absorbable glucose and reducing postprandial glycemic spikes [16, 18]. Notable safety concerns include infusion-related reactions and immunogenicity for ERTs, and significant gastrointestinal side effects, such as flatulence and diarrhea, for intestinal inhibitors [16, 17].

Other names

Acid alpha-glucosidaseLysosomal alpha-glucosidaseGAAMaltase-glucoamylaseMGAMGlucoamylaseAcid maltase1,4-alpha-D-glucan glucohydrolase

Enzyme replacement therapy (ERT) for lysosomal glycogen clearance and competitive inhibition of intestinal alpha-glucosidases to delay carbohydrate absorption.