Applied Chemistry

Biography

Biography: Stephanie MaQuarrie

Abstract

Phenylalanine ammonia lyase (PAL, E.C.4.3.1.24) catalyzes the sponstaneous, non-oxidative deamination of L-phenylalanine (L-Phe) into trans-cinnamic acid (t-CA). One of the major clinical applications of PAL is its use in the treatment of phenylketonuria (PKU), a genetic disorder in which there is a deficiency or absence of phenylalanine hydroxylase.1-3 The absence of phenylalanine hydroxylase results in an increase of L-Phe in bodily fluids (phenylalaninemia). High levels of L-Phe can be controlled following a very strict diet restricting all phenylalanine sources. Unfortunately, L-Phe is found in high concentrations in many foods such as grains and grain products, meat and meat products and dairy and eggs. In large concentrations L-Phe is a neurotoxin and therefore, if not detected and controlled with an extremely strict diet, PKU results in severe neurological disorders before the age of one.2,4,5 Although the direct administration of PAL may appear to be a suitable treatment for PKU, PAL is very unstable and denatures at room temperature.6 There is a critical need for the development of a simple method for PAL stabilization. PAL was entrapped in ultra-large-pore mesoporous silica (ULPS) (23 nm pore diameter) generating a recyclable, separable biocatalyst. The entrapped ULPS-PAL materials showed excellent stabilization, even after significant exposure to prolonged heating. Additionally, the entrapped ULPS-PAL materials showed extremely high catalytic activity in the deamination of L-phenylalanine to trans-cinnamic acid in aqueous solution and were recovered and recycled up to five times without any observable loss in activity. This approach is simple and capitalizes on the facile synthesis and easy recoverability of mesoporous silicas to generate a stable, reusable PAL based biocatalyst.