Fibrinogen heterogeneity in homozygous plasminogen deficiency type I: further evidence that plasmin is not involved in formation of LMW- and LMW'-fibrinogen.
Human plasma fibrinogen is heterogeneous in SDS-polyacrylamide gel electrophoresis and other methods for separation of proteins by molecular size. A high molecular weight fraction (HMW-fibrinogen, 340 kD) contributes approximately 50% of total fibrinogen antigen. Low molecular weight fibrinogen (LMW-fibrinogen, 300 kD) adds another 40%. The residual amount is LMW'-fibrinogen with a molecular weight of 280 kD, and a small amount of very high molecular weight fibrinogen (Fib420), the product of alternative splicing of the A alpha-chain genetic information, resulting in an extended A alpha-chain C-terminus. Fibrinogen was detected by specific immunostaining of nonreduced SDS-PAGE gel immunoblots with antibodies against fibrinopeptide A. Using densitometric scans of the immunoblots we found a ratio of HMW-, LMW- and LMW'-fibrinogen in a patient with homozygous plasminogen deficiency that was similar to the ratio found in immunoblots of plasma from healthy blood donors. Treatment with plasminogen concentrate resulted in a slight decrease of the proportion of HMW-fibrinogen, followed by an increase to 78%. The LMW'-fibrinogen band gained intensity initially, increasing to 11.9% of fibrinogen antigen 6 h after starting plasminogen infusion, but then dropped to levels below detection limit of the immunoblotting assay. LMW-fibrinogen remained constant during the initial 72 h of plasminogen treatment, then dropping to values in the range of 22-25% afterwards. The proportion of HMW-, LMW-, and LMW'-fibrinogen again reached the initial levels two weeks after starting treatment with plasminogen concentrate. We conclude that plasminogen is not involved in the limited proteolysis leading to formation of LMW-fibrinogen and LMW'-fibrinogen in the absence of a generalized fibrinolytic condition. Fibrinolytic activation may lead to the formation of fibrinogen degradation product X, which appears in a similar position as LMW'-fibrinogen in SDS-PAGE.
Dempfle
C E
CE
University of Heidelberg, Klinikum Mannheim, Germany.
Pfitzner
S A
SA
Schott
D
D
Niessen
K H
KH
Heene
D L
DL
D017398:Alternative Splicing; D003241:Consanguinity; D019281:Dimerization; D005260:Female; D005340:Fibrinogen / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics*; D006580:Genetic Carrier Screening; D006720:Homozygote; D006801:Humans; D015151:Immunoblotting; D007223:Infant; D008297:Male; D008970:Molecular Weight; D010958:Plasminogen / Q000172:deficiency* / Q000627:therapeutic use; D012016:Reference Values
D005340:Fibrinogen; D010958:Plasminogen