Biochemical characterization and kinetic studies on a purified yellow laccase from newly isolated Aureobasidium pullulans NAC8 obtained from soil containing decayed plant matter Adedeji Nelson Ademakinwa, Femi Kayode Agboola * Department of Biochemistry, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria Received 6 January 2016; revised 9 April 2016; accepted 8 May 2016 KEYWORDS Yellow laccase; Aureobasidium pullulans NAC8; Kinetics; Biochemical characterization Abstract The study investigated the biochemical characteristics and kinetic parameters of laccase from a newly isolated Aureobasidium pullulans NAC8 obtained from soil containing decay plant lit- ters. This was with a view to identifying the type of laccase and its possible suitability for biotech- nological applications. The fungal strain was identified as A. pullulans NAC8 by sequencing of its 5.8S rRNA and adjacent internally transcribed sequences (ITS) 1 and 2. A. pullulans NAC8 laccase was purified 2.0-fold with a yield of 59.3% and specific activity of 9.34 lmol/min/mg protein. The kinetic param- eters K M , V max , k cat and k cat /K M for laccase with guaiacol as substrate were 1.05 ± 0.12 mM, 12.67 ± 0.55 lmol/ml/min, 25.3  10 1 s 1 and 2.4  10 3 M 1 s 1 respectively. Laccase exhibited maxi- mum activity at 45 °C and optimum pH of 4.5. The enzyme showed stability at a temperature range of 45–55 °C after a 2 h incubation. The molecular weight determined on SDS–PAGE was 68.4 kDa. The enzyme was stable at 10% of all organic solvents used but displayed a loss of activity at 50%. 2.5 mM thioglycolic acid (TGA) and 0.05 mM sodium azide inactivated the enzyme. The substrate specificity was guaiacol > catechol > tannic acid > gallic acid. There was no peak observed at 610 nm and the ratio of absorbance at 280 nm and 610 was 26. This suggests a yellow laccase. The biochemical properties of A. pullulans NAC8 yellow laccase makes it potentially useful in several biotechnological applications. Ó 2016 Production and Hosting by Elsevier B.V. on behalf of Academy of Scientific Research & Technology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/). 1. Introduction Laccases (benzenediol:oxygen oxidoreductases; EC 1.10.3.2), multicopper enzymes belonging to the blue oxidases, catalyze the one-electron abstraction from a wide variety of organic * Corresponding author. Tel.: +234 8034738078. E-mail addresses: fkagbo@oauife.edu.ng, fagboola@yahoo.com (F.K. Agboola). Peer review under responsibility of National Research Center, Egypt. Journal of Genetic Engineering and Biotechnology (2016) xxx, xxx–xxx HOSTED BY Academy of Scientific Research & Technology and National Research Center, Egypt Journal of Genetic Engineering and Biotechnology www.elsevier.com/locate/jgeb http://dx.doi.org/10.1016/j.jgeb.2016.05.004 1687-157X Ó 2016 Production and Hosting by Elsevier B.V. on behalf of Academy of Scientific Research & Technology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Please cite this article in press as: A.N. Ademakinwa, F.K. Agboola, Journal of Genetic Engineering and Biotechnology (2016), http://dx.doi.org/10.1016/j. jgeb.2016.05.004