Effective production of retinal from β-carotene using recombinant mouse β-carotene 15,15′-monooxygenase.

The gene encoding β-carotene 15,15′-monooxygenase from Mus musculus (house mouse), which cleaves β-carotene into two molecules of retinal, was cloned and expressed in Escherichia coli. The expressed enzyme was purified by His-tag affinity and resource Q ion exchange chromatography columns to a final specific activity of 0.51 U mg−1. The optimum pH, temperature, substrate and detergent concentrations, and enzyme amount for effective retinal production were determined to be 9.0, 37°C, 200 mg l−1 β-carotene, 5% (w/v) Tween 40, and 0.2 U ml−1 enzyme, respectively. Under optimum conditions, the recombinant enzyme produced 72 mg l−1 retinal in a 15-h reaction time, with a conversion yield of 36% (w/w). The specific activity of the purified enzyme and retinal production obtained in the present study were the highest results ever reported. [ABSTRACT FROM AUTHOR]