Interaction of blood coagulation factor Va with phospholipid vesicles examined by using lipophilic photoreagents

Journal Article · Tue Jan 13 04:00:00 EST 1987 · Biochemistry; (United States)

OSTI ID:6525802

Krieg, U C; Isaacs, B S; Yemul, S S; Esmon, C T; Bayley, H; Johnson, A E

Two different lipophilic photoreagents, (/sup 3/H)adamantane diazirine and 3-(trifluoromethyl)-3-(m-(/sup 125/I)iodophenyl)diazirine (TID), have been utilized to examine the interactions of blood coagulation factor Va with calcium, prothrombin, factor Xa, and, in particular, phospholipid vesicles. With each of these structurally dissimilar reagents, the extent of photolabeling of factor Va was greater when the protein was bound to a membrane surface than when it was free in solution. Specifically, the covalent photoreaction with Vl, the smaller subunit of factor Va, was 2-fold higher in the presence of phosphatidylcholine/phosphatidylserine (PC/PS, 3:1) vesicles, to which factor Va binds, than in the presence of 100% PC vesicles, to which the protein does not bind. However, the magnitude of the PC/PS-dependent photolabeling was much less than has been observed previously with integral membrane proteins. It therefore appears that the binding of factor Va to the membrane surface exposes Vl to the lipid core of the bilayer, but that only a small portion of the Vl polypeptide is exposed to, or embedded in, the bilayer core. Addition of either prothrombin or active-site-blocked factor Xa to PC/PS-bound factor Va had little effect on the photolabeling of Vl with TID, but reduced substantially the covalent labeling of Vh, the larger subunit of factor Va. This indicates that prothrombin and factor Xa each cover nonpolar surfaces on Vh when the macromolecules associate on the PC/PS surface. It therefore seems likely that the formation of the prothrombinase complex involves a direct interaction between Vh and factor Xa and between Vh and prothrombin.(ABSTRACT TRUNCATED AT 250 WORDS)

• Research Organization: Univ. of Oklahoma, Norman
• OSTI ID: 6525802
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 1; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADAMANTANE
ALKANES
ANIMALS
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BLOOD COAGULATION FACTORS
CATTLE
CELL CONSTITUENTS
CHEMISTRY
COAGULANTS
CYCLOALKANES
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
ESTERS
HEMATOLOGIC AGENTS
HYDROCARBONS
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPES
KINETICS
LABELLED COMPOUNDS
LIPIDS
LIPOSOMES
MAMMALS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
ORGANOIDS
PHOSPHOLIPIDS
PHOTOCHEMISTRY
PROTHROMBIN
RADIOISOTOPES
REACTION KINETICS
RUMINANTS
TRITIUM COMPOUNDS
VERTEBRATES