Related Experiment Video
Updated: Mar 3, 2026

In Vitro Enzyme Measurement to Test Pharmacological Chaperone Responsiveness in Fabry and Pompe Disease
Published on: December 20, 2017
Engineering and Characterization of an Enzyme Replacement Therapy for Classical Homocystinuria
Tomas Majtan1, Insun Park1, Richard S Carrillo1
1Department of Pediatrics, University of Colorado School of Medicine , Aurora, Colorado 80045, United States.
Abstract:
Homocystinuria due to loss of cystathionine beta-synthase (CBS) causes accumulation of homocysteine and depletion of cysteine. Current treatments are suboptimal, and thus the development of an enzyme replacement therapy based on PEGylated human truncated CBS (PEG-CBS) has been initiated. Attenuation of potency was observed, which necessitated a screen of several PEG-CBS conjugates for their efficacy to correct and maintain the plasma metabolite profile of murine homocystinuria after repeated administrations interrupted with washouts. We found that CBS coupling with maleimide PEG inconsistently modified the enzyme. In contrast, the PEG-CBS conjugate with 20 kDa N-hydroxysuccinimide-PEG showed very little loss of potency likely due to a reproducible PEGylation resulting in species modified with five PEGs per subunit on average. We developed assays suitable for monitoring the extent of CBS PEGylation and demonstrated a sustainable partial normalization of homocystinuria upon continuous PEG-CBS administration via osmotic pumps. Taken together, we identified the PEG-CBS conjugate suitable for manufacturing and clinical development.
More Related Videos
Related Concept Videos
Pharmacogenetics of Phase II Enzymes: N-acetyltransferase, Thiopurine S-methyltransferase, UDP-glucuronosyltransferase
Catalytically Perfect Enzymes
Most enzymes...
Pharmacogenetics of Phase I Enzymes: Cytochrome P450 Isozymes

