Investigation ofkinetic aspects of L-phenylanine ammonia-lyase production in pigmental yeast
Kinetic aspects of L-phenylanine production
A model of a continuous L-phenylalanine ammonia-lyase (PAL) fermentation process by Aureobasidium pullulans (Y863) pigment yeast strain was developed. As a basis of the kinetic model, differential equations of Luedeking-Piret model combined with Monod were used. It was found that the kinetic growth of Aureobasidium pullulans (Y863) and synthesis of PAL were carried out not only in case of decrease of phenylalanine content in the substrate, but also in the course of biosynthesis of the desired product. As an effective criterion of the biokinetics’ selected performance, the PAL target product was selected, determined by the quantity of the substrate stream and the concentration of the target product in the culture medium. The obtained dependencies of the phenylalanine concentration in the nutrient solution for every fixed value of the feed stream have a unified dynamics of change. The obtained kinetic dependences can be used for both qualitative and quantitative characteristics of the process in the development of PAL production technology.
The issue of use of enzymes in different areas of the economy has attraced a lot of interest from around the world, making the search for novel commercial primary sources particularly important.
L-phenylalanine ammonia-lyase (PAL, EC 220.127.116.11) is one of the enzymes that can be used in various medical applications, i.e. for direct phenylketonuria therapy, in high-grade phenylalanine-free food manifacture, and for malignant cells growth inhibition (1,2). In addition, this enzyme can be used for L-phenylalanine production in biotechnology using trans-?innamic acid (3). L-phenylalanine ammonia-lyase belongs to the family of lyases catalyzing the reaction of the nonoxidative deamination of L-phenylalanine with the formation of trans-cinnamic acid and free ammonium ion.
In most cases, PAL molecule has a molecular weight ranging from 300 to 340 kDa (4). According to various researchers, there are exceptions to this rule: molecules with molecular weight of 152 kDa, 226 kDa, 250 kDa, 560 kDa.
Conformations of PAL, isolated from different sources, are more or less spherical (5). Usually, L-phenylalanin ...