Trimeric l-N-carbamoylase from newly isolated Brevibacillus reuszeri HSN1: a potential biocatalyst for production of l-α-amino acids.

l-N-carbamoylase was isolated from Brevibacillus reuszeri HSN1 and purified to homogeneity in three steps, which is a reasonably short protocol for native l-N-carbamoylase. The enzyme purification protocol resulted in ≈60-fold purification of l-N-carbamoylase with specific activity of 145 µmol/Min/mg. The subunit and native molecular mass were found to be 44.3 and 132 kDa, respectively. Temperature and pH optima were determined as 50°C and 8.5, respectively. The enzyme had retained ≈86% activity at 50°C when incubated for 60 Min and the half-life was determined as 180 Min at 50°C. N-carbamoyl-l-methionine (l-N-CMet) was found to be a preferred substrate with Km and Vmax values of ≈13.5 mM and ≈103 µmol/Min/mg, respectively. The broad substrate specificity with derivatives of N-carbamoyl amino acids is advantageous to be a better biocatalyst for production of corresponding l-α-amino acids. The enzyme activity was enhanced by 73% in the presence of 0.8 mM Mn(2+) ion during the biotransformation. In the batch experiment, ≈97% conversion of 5.0% l-N-CMet into enantiomerically pure l-methionine was achieved in 10 H when carried out at pH 8.0, 45°C, and 15% wet (w/v) cell loading, under controlled conditions. The overall merits of this enzyme show promise as a potential biocatalyst for l-α-amino acid production.