Biotoxin Units, Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, the Chinese Academy of Sciences, Kunming Yunnan 650223, China; 2. Department of Urology, the First Affiliated Hospital of Kunming Medical College. Kunming Yunnan 650032, China; 3. Department of Urology, West China Hospital, Sichuan University, Chengdu Sichuan 610041, China
Nucleotide sequence coding for SgI-52 with amino acid residues of 85-136 form mature human semenogelin I was amplified by PCR technique from the cDNA of a human seminal vesicle. The obtained PCR products were inserted into vector pMAL-p2X. The constructed expression vector of pMAL-p2X/SgI-52 was transformed into Escherichia coli DH5α. Fusion protein was expressed in the periplasma of the E. coli DH5αafter IPTG inducement. Recombinant SgI-52 was purified after factor X cleavage and a ultrafiltering process. MALDI-TOF- MS results indicated that the purified recombinant SgI-52 was the target peptide. Recombinant SgI-52 showed antibacterial activities on E. coli ATCC 25922 and E. coli ML-35P with MIC values of 32.45 and 46.30 μg/mL, respectively. Our results and other relevant works suggested that different human semenogelin I degradation fragments during the liquefaction might have various biological functions and deserve to be investigated further.