A Silk-Based Platform to Stabilize Phenylalanine Ammonia-lyase for Orally Administered Enzyme Replacement Therapy

Mol Pharm. 2022 Dec 5;19(12):4625-4630. doi: 10.1021/acs.molpharmaceut.2c00512. Epub 2022 Jul 21.

Abstract

Phenylalanine ammonia-lyase (PAL) has gained attention in recent years for the treatment of phenylketonuria (PKU), a genetic disorder that affects ∼1 in 15 000 individuals globally. However, the enzyme is easily degraded by proteases, unstable at room temperature, and currently administered in PKU patients as daily subcutaneous injections. We report here the stabilization of the PAL from Anabaena variabilis, which is currently used to formulate pegvaliase, through incorporation in a silk fibroin matrix. The combination with silk stabilizes PAL at 37 °C. In addition, in vitro studies showed that inclusion in a silk matrix preserves the biological activity of the enzyme in simulated intestinal fluid, which will enable oral administration of PAL to treat PKU.

Keywords: PKU; oral delivery; phenylalanine ammonia-lyase; protein stability; silk fibroin.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Enzyme Replacement Therapy
  • Humans
  • Phenylalanine Ammonia-Lyase* / genetics
  • Phenylalanine Ammonia-Lyase* / metabolism
  • Phenylketonurias* / drug therapy
  • Phenylketonurias* / metabolism
  • Silk

Substances

  • Phenylalanine Ammonia-Lyase
  • Silk