Leptin pegylated antagonist (mutant L39A/D40A/F41A)

Mono-pegylated (with 20 kDa PEG) recombinant rat leptin antagonist is 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 pegylated recombinant rat leptin antagonist runs on the SDS-PAGE as 48 kDa protein and on gel-filtration Superdex 200 column as over 100 kDa protein. The half-life of recombinant rat leptin antagonist in circulation after SC injection was over 20 hours. Recombinant rat leptin was initially mutated, resulting in L39A/D40A/F41A mutant that was purified by proprietary chromatographic techniques according to Salomon et al (2006) Protein Expression and Purification 47, 128–136.