An intracellular nitrilase (Nit1) with cyanide-degrading activity was isolated from Trichoderma harzianum VSL291, cultivated on benzonitrile as the sole carbon source. Nit1 was purified to homogeneity by ion exchange and gel filtration chromatography with a recovery of and a fold of . | Turkish Journal of Biology Research Article Turk J Biol (2015) 39: 248-257 © TÜBİTAK doi: Purification and characterization of a cyanide-degrading nitrilase from Trichoderma harzianum VSL291 Jorge RICAÑO-RODRÍGUEZ, Mario RAMÍREZ-LEPE* Unit for Research and Development in Food, Technological Institute of Veracruz, Veracruz, Mexico Received: Accepted: Published Online: Printed: Abstract: An intracellular nitrilase (Nit1) with cyanide-degrading activity was isolated from Trichoderma harzianum VSL291, cultivated on benzonitrile as the sole carbon source. Nit1 was purified to homogeneity by ion exchange and gel filtration chromatography with a recovery of and a fold of . The molecular weight was estimated to be kDa and the purified enzyme was sequenced with a system of liquid chromatography and mass spectrometry (LC-MS). The enzyme consists of 436 amino acids with a predicted molecular weight of kDa. The sequence revealed conserved domains for a nitrilase super family such as putative active and binding sites and a Glu-Lys-Cys catalytic triad. Nit1 exhibited maximum activity ( U mg–1) at 40 °C and a pH of . Nit1 had a strong inhibition in the presence of Al3+, Cu2+, Zn2+, and Ag+ ions and was able to degrade KCN completely at mmol/L, mmol/L, and mmol/L in 15 min, 40 min, and 45 min, respectively. The effect on KCN ( mmol/L) degradation was tested in the presence of Cu2+ and Ag+ ions ( mmol/L to mmol/L) and the enzymatic activity was not affected significantly at mmol/L, mmol/L, and mmol/L concentrations. However, when both ions were combined, the activity of the enzyme decreased significantly. Key words: Cyanide-degrading nitrilase, bioremediation, enzyme characterization, purification, Trichoderma 1. Introduction Nitrilase enzymes (nitrilases) catalyze the hydrolysis of nitrile (R-CN) .
