High-yield production of functionally active human serum transferrin using a baculovirus expression system, and its structural characterization.

Recently, there has been much interest in expressing recombinant human serum transferrin (HST) and mutants thereof for structural and functional studies. We have developed a baculovirus expression system for the rapid and efficient production of large quantities of HST (> 20 mg/l). Like native HST, the recombinant protein can bind two ferric ions in the presence of bicarbonate, and is actively taken up by receptor-mediated endocytosis. Secondary structure calculations from CD measurements indicate a content of 42% alpha-helix and 28% beta-sheet. This is the first reported use of a non-mammalian expression system to produce functional HST, and will provide a practical tool to allow expression of a wide range of HST variants for mutagenesis studies.