Reduction of l-phenylalanine in protein hydrolysates using l-phenylalanine ammonia-lyase from Rhodosporidium toruloides


l-Phenylalanine ammonia-lyase (PAL, EC from Rhodosporidium toruloides was utilized to remove l-phenylalanine (l-Phe) from different commercial protein hydrolysates. A casein acid hydrolysate (CAH, l-Phe ~2.28 %) was employed as a model substrate. t-Cinnamic acid resulting from deamination of l-Phe was extracted, analyzed at λ = 290 nm, and used for PAL activity determination. Optimum reaction conditions, optimized using successive Doehlert design, were 35 mg mL−1 of CAH and 800 mU mL−1 of PAL, while temperature and pH were 42 °C and 8.7, respectively. Reaction kinetics of PAL with CAH was determined under optimized conditions. Then, removal of l-Phe from CAH was tested. Results showed that more than 92 % of initial l-Phe was eliminated. Similar results were obtained with other protein hydrolysates. These findings demonstrate that PAL is a useful biocatalyst for l-Phe removal from protein hydrolysates, which can be evaluated as potential ingredients in foodstuffs for PKU patients.

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This research was supported by grants from the Argentina National Research Council (CONICET, PIP 0662), the National University of La Plata (UNLP, 11/X650), and the National Technological University (UTN, 25/I060). In addition, a part of this work was supported by FY 2011-2013 Grant-in-Aid for Scientific Research (C), Japan Society for the Promotion of Science KAKENHI 23580135 to O. Adachi. Authors extend their appreciation to Ms. Alicia María Noceti and Dr. Gustavo J. C. Borrajo for their assistance.

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Correspondence to Roque Alberto Hours.

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This paper is dedicated to the memory of our dear colleague, Prof. Carlos F. Mignone, who recently passed away.

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Castañeda, M.T., Adachi, O. & Hours, R.A. Reduction of l-phenylalanine in protein hydrolysates using l-phenylalanine ammonia-lyase from Rhodosporidium toruloides . J Ind Microbiol Biotechnol 42, 1299–1307 (2015).

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  • Phenylketonuria
  • Phenylalanine ammonia-lyase
  • Rhodosporidium toruloides
  • Casein acid hydrolysate
  • l-Phe removal