Cloning and overexpression of LdSS in the pET28a(+) vector. (A) PCR amplification of LdSS cDNA. Lane 1, 1-kb DNA ladder; lane 2, amplified band of LdSS, showing a size of around 900 bp. (B) Confirmation of the LdSS clone in the pET28a(+) vector by PCR. Lane 1, 1-kb ladder; lane 2, amplified band of 900 bp from the LdSS clone in the pET28a(+) vector. (C) Confirmation of the LdSS clone in the pET28a(+) vector by restriction digestion. Lane 1, 1-kb ladder; lane 2, restriction digestion of the clone with NheI and BamHI, showing release of an insert of 900 bp; lane 3, restriction digestion of the clone with NheI only; lane 4, undigested LdSS clone in the pET28a(+) vector. (D) SDS-PAGE analysis of purified LdSS protein. Lane 1, protein molecular size marker; lane 2, crude supernatant; lane 3, purified recombinant LdSS protein.