Abstract: Recombinant lysostaphin（rLysn）,duo to its solid antibacterial activity to Staphylococcal aureus,is novel antibacterial medicine,and therapeutic agent containing this enzyme may efficiently control the infection of S. aureus. In order to control the quality of pharmaceutical preparations with rLysn,a method of measuring the protein content in the final product with rLysn was established and verified. Size exclusion high performance liquid chromatograph（SE-HPLC）was employed to measure the protein content in both physico-chemical control and the final product with rLysn under the conditions as below：a TSK gel 2000SWXL column（7.8 mm×30 cm,5 µm）,the mobile phase composed of phosphate buffer（20 mmol/L,pH7.0）and NaCl（0.3 mol/L）,the flow rate was 0.5 mL/min,the temperature was 25℃,and the detection wave length was 280 nm. As results,the rLysn（within 2-32 µg）was linearly correlated with the area of the elution peak（r² =1）. The weighted average recovery rate for physico-chemical controls in 3 rLysn concentrations of low,medium and high was 102.9%,while the weighted average recovery rate was 102.1%. Three supernatants were measured at different time,and RSD of protein content < 1%;while measurement was done for each supernatant in 1 h interval,RSD of the protein content was 0.98%;and 6 samples from one targeted solution were measured,RSD of the protein content was 1.71%. Above results reveal that SE-HPLC is simple and convenient,accurate,precise,stable and repeatable approach,thus may be used for the determination of protein content in the final product of rLysn.

Key words: recombinant lysostaphin, protein content, size exclusion high performance liquid chromatography