Open AccessProtease inhibitors from the parasitic worm Parascaris equorum
Author(s) -
CONCETTI Antonio,
FIORETTI Evandro,
BARRA Donatella,
ASCOLI Franca
Publication year - 1984
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1984.tb08570.x
Subject(s) - chemistry , proteases , trypsin , isoelectric point , serine protease , chymotrypsin , protease , biochemistry , enzyme , affinity chromatography , serine , serine proteinase inhibitors , elastase , isoelectric focusing , protease inhibitor (pharmacology) , enzyme inhibitor , chromatography , biology , human immunodeficiency virus (hiv) , antiretroviral therapy , viral load , immunology
Two proteic inhibitors (I and II) of serine proteases have been purified from the parasitic worm Parascaris equorum by affinity chromatography on immobilized trypsin followed by preparative electrophoresis. They have an apparent relative molecular mass of 9000 and 7000 as determined by gel filtration, a slightly acid isoelectric point (5.5 and 6.1) and a similar amino acid composition. Both inhibitors lack serine, methionine and tyrosine. They bind bovine trypsin extremely strongly with an association constant, K a , larger than 10 9 M –1 , and form a 1:1 complex with this protease. The K a values for the binding to bovine chymotrypsin are ∼ 3.3 × 10 8 M –1 (inhibitor I) and ∼ 2 × 10 6 M –1 (inhibitor II). Inhibitor I interacts also with porcine elastase ( K a ∼ 5 × 10 7 M –1 ), while inhibitor II is inactive towards this enzyme.