Topography of the high-affinity lysine binding site of plasminogen as defined with a specific antibody probe
An antibody population that reacted with the high-affinity lysine binding site of human plasminogen was elicited by immunizing rabbits with an elastase degradation product containing kringles 1-3 (EDP I). This antibody was immunopurified by affinity chromatography on plasminogen-Sepharose and elution with 0.2 M 6-aminohexanoic acid. The eluted antibodies bound (/sup 125/I)EDP I, (/sup 125/I)Glu-plasminogen, and (/sup 125/I)Lys-plasminogen in radioimmunoassays, and binding of each ligand was at least 99% inhibited by 0.2 M 6-aminohexanoic acid. The concentrations for 50% inhibition of (/sup 125/I)EDP I binding by tranexamic acid, 6-aminohexanoic acid, and lysine were 2.6, 46, and l730 ..mu..M, respectively. Similar values were obtained with plasminogen and suggested that an unoccupied high-affinity lysine binding site was required for antibody recognition. The antiserum reacted exclusively with plasminogen derivatives containing the EDP I region and did not react with those lacking an EDP I region, or with tissue plasminogen activator or prothrombin, which also contains kringles. By immunoblotting analyses, a chymotryptic degradation product of M/sub r/ 20,000 was derived from EDP I that retained reactivity with the antibody. ..cap alpha../sub 2/-Antiplasmin inhibited the binding of radiolabeled EDP I, Glu-plasminogen, or Lys-plasminogen by the antiserum, suggesting that the recognized site is involved in the noncovalent interaction of the inhibitor with plasminogen. The binding of (/sup 125/I)EDP I to fibrin was also inhibited by the antiserum. The observations provide independent evidence for the role of the high-affinity lysine binding site in the functional interactions of plasminogen with its primary substrate and inhibitor.
- Research Organization:
- Research Institute of Scripps Clinic, La Jolla, CA
- OSTI ID:
- 6549137
- Journal Information:
- Biochemistry; (United States), Vol. 25:22
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
LABELLED COMPOUNDS
CONFIGURATION INTERACTION
PLASMINOGEN
BIODEGRADATION
RADIOIMMUNOASSAY
ANTIBODIES
FIBRIN
IODINE 125
ION EXCHANGE CHROMATOGRAPHY
LYSINE
AMINO ACIDS
BETA DECAY RADIOISOTOPES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CHROMATOGRAPHY
COAGULANTS
DAYS LIVING RADIOISOTOPES
DECOMPOSITION
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
FIBRINOLYTIC AGENTS
HEMATOLOGIC AGENTS
HEMOSTATICS
IMMUNOASSAY
IMMUNOLOGY
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
PROTEINS
RADIOASSAY
RADIOIMMUNOLOGY
RADIOISOTOPES
SCLEROPROTEINS
SEPARATION PROCESSES
TRACER TECHNIQUES
550601* - Medicine- Unsealed Radionuclides in Diagnostics