Summary
Δ2−89 t-PA is a deletion mutant lacking the finger (F) and epidermal growth factor (EGF)
domains; thus, the fibrin interaction of this molecule must be mediated solely by
the kringle region. In the present study, the influence of the oligosaccharide side-chains
on the activity of Δ2−89 t-PA has been investigated. Δ2−89 t-PA was secreted in two forms, designated I and II, which presumably differ by the
lack of one asparagine-linked oligosaccharide in the kiiugle 2 domain of form TT,
Forms I and II of Δ2−89 t-PA weie puiified; form II displayed higher fibrinolytic activity than form I. When
foini I was partially deglycosylated or treated to remove sialic acid, fibrinolytic
activity was increased. Production of Δ2−89 in the presence of timicamycin led to secielion of a glyean-free activator with higher
activity. These findings suggest that certain oligusacchaiide side chains, particularly
(hose containing sialic acid, can interfere with the interaction between the kringle
region of t-PA and fibrin.