Abstract: This study used the cbs gene sequence of brewing yeast as a template and optimized codons based on the codon preference of Escherichia coli BL21 （DE3）. The expression plasmid pET28a-cbs was constructed using pET28a（+） as the skeleton, and the cystathionine β-synthase （CBS） was expressed using Escherichia coli BL21 （DE3）. The inducing expression conditions were optimized and the enzymatic properties of CBS were analyzed. The results showed that the highest concentration of CBS was 266.67 mg/L at an induction temperature of 16 ℃, IPTG concentration of 0.1 mmol/L, and induction time of 18 hours.During the catalytic process of CBS, it was also influenced by various environmental factors. At 40~50 ℃, the relative enzyme activity of CBS rapidly decreased, and CBS was not suitable for long-term storage in environments with temperatures above 40 ℃;CBS was suitable for long-term storage in buffer solutions with pH ranging from 6.5 to 8.5, and should not be stored in buffer solutions that were too acidic or too alkaline;CBS exhibited high enzyme activity at a temperature of 40 ℃ and pH 8.0.

Key words: cystathionine β-synthase（CBS）, efficient expression, enzymatic properties, inducing expression