Partial purification, experimental characterization of L-arginase from Alcaligenes aquatilis BC2 and determination of in vitro anticancer activity

L-arginase catalyzes the hydrolysis of L-arginine into L-ornithine and urea and plays a key role in the urea cycle. Interest in microbial L-arginases has increased because of their potential biotechnological and biomedical applications, including arginine-deprivation approaches in cancer research. In this study, extracellular L-arginase from Alcaligenes aquatilis BC2 was partially purified and biochemically characterized. Ethanol precipitation achieved a 3.31-fold purification with a specific activity of 357.95 U/mg. The enzyme showed optimal activity at 40 °C and pH 9.0, retained moderate thermal stability up to 50 °C, and remained stable under alkaline conditions. Kinetic analysis yielded a Michaelis–Menten constant (Km) of 4.275 mM and a maximum velocity (Vmax) of 44.444 µmol/min/mL. Enzyme activity increased in the presence of Mn²⁺, supporting its role as a cofactor. In addition, the partially purified enzyme exhibited in vitro antiproliferative effects against U87MG human glioblastoma cells, with an IC 50 value of 43.75 µg/mL. Overall, these results indicate that L-arginase from A. aquatilis BC2 possesses biochemical properties that may be relevant for future biotechnological and biomedical investigations. However, additional purification, mechanistic studies, and in vivo evaluations are required to further assess its potential applications.