Expression and purification of a recombinant avidin with a lowered isoelectric point in <i>Pichia pastoris</i>

A recombinant glycosylated avidin (recGAvi) with an acidic isoelectric point was expressed and secreted by the methylotrophic yeast <i>Pichia pastoris</i>. The coding sequence for recGAvi was de novo synthesized based on the codon usage of <i>P. pastoris</i>. RecGAvi is secreted at approximately 330 mg/L of culture supernatant. RecGAvi monomer displays a molecular weight of 16.5 kDa, as assessed by ESI mass spectrometry. N-terminal amino acid sequencing indicates the presence of three additional amino acids (E-A-E), which contribute to further lowering the isoelectric point to 5.4. The data presented here demonstrate that the <i>P. pastoris</i> system is suitable for the production of recGAvi and that the recombinant avidin displays biotin-binding properties similar to those of the hen-egg white protein.