Rat Leptin, Pegylated Recombinant Protein

Mono-pegylated (with 20 kDa PEG) recombinant rat leptin is an one polypeptide chain containing 146 amino, an additional Ala at N-terminus and one molecule of PEG 20 kDa at its N-terminus, having an expected molecular mass of ~ 35.6 kDa as determined by MS. However due to enlarged hydrodymanic volume it runs on the SDS-PAGE as 48 kDa protein and in gel-filtration on Superdex 200 as over 100 kDa protein. The half-life in circulation of pegylated recombinant rat leptin after SC injection was over 20 hours. Recombinant rat leptin as purified by proprietary chromatographic techniques according to Salomon et al (2006) Protein Expression and Purification 47, 128–136 and then pegylated.