Purification and characterisation of plasminogen activator inhibitor 2 produced in Saccharomyces cerevisiae

Abstract
Expression of plasminogen activator inhibitor 2 (PAI-2) under the control of the protease B gene promoter in a mutant strain of Saccharomyces cerevisiae, DS569, resulted in its accumulation intracellularly at up to 20% of the soluble cell protein. Provision of an N-terminal signal sequence resulted in the secretion of a hyperglycosylated molecule. The intracellularly produced PAI-2 was purified by copper-chelate and anion-exchange chromatography to > 95% pure and was fully active. The recombinant PAI-2 formed SDS-stable complexes with urokinase and tissue-type plasminogen activator and inhibited the proteases with similar reaction kinetics to placental PAI-2 (second-order rate constant for uPA, 2.4 × 106 M−1 s−1, and for two-chain tPA, 0.7 × 105 M−1 s−1). As is the case for placental PAI-2, the N-terminus of the yeast-derived recombinant PAI-2 was blocked. The high productivity and consequent ease of purification mean that S. cerevisiae provides an excellent source of recombinant PAI-2 for investigation of its therapeutic potential in the treatment of neoplastic and inflammatory diseases.

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