[Alpha-galactosidases and alpha-N-acetylgalactosaminidase. Biochemical bases of Fabry's disease]

Abstract

The first part of this review deals with the new biochemical and genetical data concerning alpha-galactosidase and alpha-N-acetylgalactosaminidase. Molecular forms of these both enzymes can be classified into two groups following their physical, enzymatic and genetical properties: - the 3 forms of the alpha-galactosidase A group differ by the number of sialyl residues and their isoelectric point. All the forms of this group are heat-labile, hydrolyse only alpha-galactosides and proceed from the same alpha-GalA, X-linked gene. - alpha-galactosidase B is an alpha-N-acetylgalactosaminidase with broad substrate specificity, in vitro, is heat-stable and proceed from the alpha- GalB or alpha- NAGA gene of the chromosome 22. Structural and enzymatic data concerning these enzymes and their functions in the catabolism of glycosphingolipids and glycoproteins are reviewed. The second part deals with the pathophysiology of Fabry disease. The more prominent genetical and biochemical data and their diagnostic uses are reported: isozymic determination, cell cloning, quantitative determination of accumulated glycolipids. At last, were pointed the new developments of the research on Fabry disease: cultured cells as experimental model (fibroblasts, lymphoid cell lines) and therapeutic attempts.