Open AccessMicroenvironment changes in human blood platelet membranes associated with binding of tissue‐type plasminogen activator
Author(s) -
WATALA Cezary,
PIETRUCHA Tadeusz,
GWOZDZINSKI Krzysztof,
KRALISZ Urszula,
CIERNIEWSKI Czeslaw S.
Publication year - 1993
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1993.tb18104.x
Subject(s) - platelet , plasminogen activator , membrane , chemistry , activator (genetics) , human blood , tissue plasminogen activator , microbiology and biotechnology , medicine , biochemistry , biology , receptor , physiology
Whole washed platelets were labelled with the free radicals [2‐(14‐carboxytetradecyl)‐2‐ethyl‐4,4‐dimethyl‐3‐oxazolidinyloxy] (16‐DOXYL‐Ste) or [2‐(3‐carboxypropyl)‐4,4‐dimethyl‐2‐tridecyl‐3‐oxazolidinyloxy] (5‐DOXYL‐Ste) and incubated with recombinant tissue‐type plasminogen activator (rt‐PA). Changes in the membrane fluidity caused by rt‐PA were detected by alterations in h +1 / h o calculated from the ESR spectra for 16‐DOXYL‐Ste and 5‐DOXYL‐Ste incorporated into the lipid bilayer ( h +1 and h o are the heights of the low‐field and middle‐field lines of the spectra, respectively). Interaction of rt‐PA with both resting and stimulated platelets resulted in increased rigidity of the membrane lipid bilayer as indicated by the reduced value of h +1 / h o . This phenomenon can be explained either by conformational changes of membrane receptors caused by the attachment of rt‐PA and the subsequent rearrangement of the lipid matrix of platelet membranes, or by the direct association of rt‐PA with membrane phospholipids and thus partial embedding of protein molecules into the lipid bilayer restraining lipid mobility.