Evidence for a second type of fibril branch point in fibrin polymer networks, the trimolecular junction.
Fibrin molecules polymerize to double-stranded fibrils by intermolecular end-to-middle domain pairing of complementary polymerization sites, accompanied by fibril branching to form a clot network. Mass/length measurements on scanning transmission electron microscopic images of fibrils comprising branch points showed two types of junctions. Tetramolecular junctions occur when two fibrils converge, creating a third branch with twice the mass/length of its constituents. Newly recognized trimolecular junctions have three fibril branches of equal mass/length, and occur when an extraneous fibrin molecule initiates branching in a propagating fibril by bridging across two unpaired complementary polymerization sites. When trimolecular junctions predominate, clots exhibit nearly perfect elasticity.
Mosesson
M W
MW
Sinai Samaritan Medical Center, University of Wisconsin Medical School, Milwaukee 53233.
DiOrio
J P
JP
Siebenlist
K R
KR
Wall
J S
JS
Hainfeld
J F
JF
D001777:Blood Coagulation / Q000502:physiology*; D005337:Fibrin / Q000737:chemistry*; D005340:Fibrinogen / Q000737:chemistry; D006801:Humans; D017348:Microscopy, Electron, Scanning Transmission; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry*; D014945:Wound Healing / Q000502:physiology*
D011108:Polymers; D005337:Fibrin; D005340:Fibrinogen