Affinity purification of human alpha galactosidase utilizing a novel small molecule biomimetic of alpha-D-galactose

Abstract

Alpha galactosidase (a-Gal) is an acidic hydrolase that plays a critical role in hydrolyzing the terminal alpha-galactoyl moiety from glycolipids and glycoproteins. There are over a hundred mutations reported for the GLA gene that encodes a-Gal that result in reduced protein synthesis, protein instability, and reduction in function. The deficiencies of a-Gal can cause Fabry disease, a rare lysosomal storage disorder (LSD) caused by the failure to catabolize alpha-d-galactoyl glycolipid moieties. The current standard of care for Fabry disease is enzyme replacement therapy (ERT) where the purified recombinant form of human a-Gal is given to patients. The manufacture of a-Gal is currently performed utilizing traditional large-scale chromatography processes. Developing an affinity resin for the purification of a-Gal would reduce the complexity of the manufacturing process, reduce costs, and potentially produce a higher quality a-Gal. After the evaluation of many small molecules, a commercially available small molecule biomimetic, N-5-Carboxypentyl-1-deoxygalactonojirimycin (N5C-DGJ), was utilized for the development of a novel small molecule biomimetic affinity resin for a-Gal. Affinity purified a-Gal demonstrated a purity greater than 90%, exhibited expected thermal stability and specific activity. Complementing this affinity purification is the development of an elution buffer system that confers an increased thermal stability to a-Gal. The N5C-DGJ affinity resin tolerated sodium hydroxide sanitization with no loss of binding capacity, making it amenable to large scale purification processes and potential use in manufacturing. This novel method for purifying the challenging a-Gal enzyme can be extended to other enzyme replacement therapies.

Keywords: Alpha galactosidase; Biomimetic; Characterization; N-5-Carboxypentyl-1-deoxygalactonojirimycin.