Rodent and Human Acid α‐Glucosidase

Abstract

The lysosomal acid a-glucosidase has been purified more than 10000-fold from rat and mice liver and from human placenta. The kinetic properties of the human enzyme are similar to those previously described for the rodent enzyme, with the main exception of the absence of inhibition by an excess of maltose. Antibodies were obtained by injection of the pure rat liver, mouse liver or human placental or-glucosidase to rabbits. The property of the enzyme of hydrolysing glycogen or to catalyse transglucosylation from maltose to glycogen could be nearly completely inhibited by the antibodies whereas the hydrolysis of small molecular substrates was much less inhibited. Within the same species, the same amount of enzyme was inhibited by a given amount of antibodies, whatever the tissue used as a source of enzyme. A partial cross-reactivity was observed from species to species. The presence of an immunologically reacting protein in tissues from patients with type-11-glycogenosis could not be demonstrated either by double-diffusion test or by antibodies consumption. Similar negative results were also obtained with normal human liver in which acid or-glucosidase has been inactivated a t alkaline pH.

Characterization of the molecular defect in infantile and adult acid alpha-glucosidase deficiency fibroblasts.

“…The acid a-glucosidase purified by deBarsy et al (11) was a mixture of the enzyme present in these peaks. In addition, it contained at least one more protein without enzyme activity, which was eluted from the ion-exchange column before the three enzyme peaks (Fig.…”

“…The pH of the NaCl-EDTA solution used for the elution of the column was adjusted to 5.0. Human acid a-glucosidase binds to Sephadex (11) and it was released from the Sephadex with 0.25% maltose added to the eluant. 10-ml fractions were collected at a flow rate of 30 ml/h.…”

“…However, with maltose as substrate, a residual a-1,4-glucosidase activity has been observed in leukocytes (6,8), muscle (5,6), urine (9), and cultured skin fibroblasts (10) of the adult form of the disease. By use of antibodies made against purified human placental acid a-glucosidase, lack (11)(12)(13) or severe reduction (14) of cross-reacting material has been observed in the liver and the fibroblasts of patienits with glycogenosis type II. Considerable a-glucosidase activity at pH 4.0 has been found in the kidney of patients with the infaintile form of Pompe's disease (15).…”

Purification and biochemical characterisation of human placental acid α‐glucosidase

“…In addition the distribution of acid ~x-glucosidase in human liver and skeletal muscle has been reported by Brown & Brown (8). Barring preliminary investigations by de Barsy et al (1), no further reports on the biochemical properties of the human placental acid c~-glucosidase have been forthcoming.…”

Investigation of the α‐Galactosidase Deficiency in Fabry's Disease Using Antibodies against the Purified Enzyme

“…It is therefore important to investigate if crossreacting immunological material is present in those cases where replacement of the missing enzyme activity is considered. In the group of lysosomal storage diseases such investigations have thus far only been carried out in metachromatic leukodystrophy [8], Pompe's disease [9] and GMII-gangliosidosis [lo, 111.…”