New inhibitor of the erythrina caffra type and its use to purity serine proteases.

摘要

A polypeptide which has the activity of an inhibitor DE-3 from Erythrina caffra and which reversibly and selectively binds serine proteases from a protein mixture is obtainable by culturing prokaryotic or eukaryotic host cells which have been transformed or transfected with a nucleic acid that codes for the said polypeptide in a manner that allows the host cells to express the said polypeptide under suitable nutrient conditions and isolating the said polypeptide, wherein the polypeptide has an amino acid sequence which is functionally analogous to SEQ ID NO:2, has a partial region that is more than 85% homologous to the region of amino acids 39-139 of this sequence, has two disulfide bridges and begins N-terminally with SEQ ID NO:4 or with a SEQ ID NO:4 extended N-terminally by methionine and has a binding capacity for tissue plasminogen activators of 1.25 MU/ml and more and is particularly suitable for purifying plasminogen activators such as tissue plasminogen activators (t-PA and derivatives).