Expression of a human serum albumin fragment (consisting of subdomains IA, IB, and IIA) and a study of its properties.

Site-directed mutagenesis and a yeast expression system were used to synthesize a human serum albumin (HSA) fragment (amino acids 1-297). The HSA fragment (half HSA) was evaluated with a number of biophysical techniques and found to be similar to the corresponding region in wild-type HSA. Specifically, the circular dichroism spectra of half HSA and wild-type HSA were superimposable, indicating that the highly alpha-helical secondary structure of wild-type HSA is preserved in half HSA. Additionally, half HSA was partially reactive with a polyclonal antibody against authentic HSA. Half HSA, which contains subdomain IIA, had an affinity for thyroxine and several thyroxine analogs, similar to that observed previously for wild-type HSA. This study suggests that the production of recombinant HSA fragments will be useful for the study of HSA ligand interactions.