Purification of polyphenol oxidase from Nevşehir potato (Solanum Tuberosum L.) by affinity chromatography and investigation of its kinetic and electrophoretic properties

In this work, polyphenol oxidase (PPO) enzyme, which has an economic value, was purified from Nevşehir potato (Solanum Tuberosum L.)with affinity chromatography following the ammonium sulphate precipitation and dialysis and then it was characterized. Utilized affinity gel has chemicallySepharose-4B-L-tirozin-p-aminobenzoic acid nature. PPO enzyme was obtained from Nevşehir potato with 15.16 % efficiency and 52.25 purification degree. Optimum pH and temperature studies were carried out for different substrates. Purified enzyme showed no activity against L-tyrosine and p-cresol, whereas it exhibited the maximum PPO activity against catechol, gallic acid, pyrogallol substrates. These results indicate that PPO enzyme in Nevşehir potato lacks in monophenolase (cresolase)activity and has only diphenolase (catecholase) activity. In optimum pH and temperature studies, catechol showed the maximum activity at pH 7.0 and 20 0C. KM and Vmax values for catechol substrate were determined as 5 mM and 5000 U/mLmin, respectively. IC50 and Ki values for six different inhibitors were determined. It was observed that ascorbic acid has the highest inhibition effect on the enzyme.