Physical, Chemical And Immunological Properties Of Porcine And Human Plasminogen Activators Of Various Tissues And Cells

Abstract

Properties of plasminogen activator (PA) from heart, kidney, lung and plasma euglobulin of the pig and pig kidney cell culture were compared with the properties of PA from human heart, lung, urinary urokinase (UK) and human kidney cell culture (Abbokinase, AK). The isoelectric points of PA’s were in the pi range of 7.0-7.8, except for UK and AK which had higher pI, 8.8-9.2 for the major forms. Mol. Wt. estimation by gel filtration revealed all PA, except AK, to have Mol. Wt. 48,000-54,000 with additional low Mol. Wt. forms of 25,500 and 36,000 for pig kidney cell culture PA and UK respectively. A single 35,500 form was seen for AK. Antiserum prepared against highly purified pig heart activator quenched the PA activity of pig heart, kidney, lung and euglobulin, but was inactive against pig kidney cell culture PA and UK. While pig heart PA is a poor activator of purified plasminogen and hydrolyzes AGLME poorly, pig kidney cell culture PA, UK and AK rapidly activate plasminogen and have high AGLME hydrolysis activity. A cofactor for pig heart PA (E.R. Cole, 1977, Blood 50: 262) which markedly accelerates plasminogen activation by pig heart PA, does not increase plasminogen activation by pig kidney cell culture PA, UK, AK or pig euglobulin and is instead slightly inhibitory. This data suggest that PA extracted from tissues is primarily in an inactive form, has little plasminogen activation and AGLME hydrolysis activity and is sensitive to cofactor due to unfolding of the PA with exposure of the active site. The urinary and cell culture forms of PA, in contrast, are released from cells in the active form, are insensitive to cofactor and have high plasminogen activation and AGLME hydrolysis activities.