Batroxobin Binds Fibrin with Higher Affinity and Promotes Clot Expansion to a Greater Extent than Thrombin
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Bibliographic record
Abstract
Batroxobin is a thrombin-like serine protease from the venom of Bothrops atrox moojeni that clots fibrinogen. In contrast to thrombin, which releases fibrinopeptide A and B from the NH 2 -terminal domains of the Aα- and Bβ-chains of fibrinogen, respectively, batroxobin only releases fibrinopeptide A. Because the mechanism responsible for these differences is unknown, we compared the interactions of batroxobin and thrombin with the predominant γ A /γ A isoform of fibrin(ogen) and the γ A /γ′ variant with an extended γ-chain. Thrombin binds to the γ′-chain and forms a higher affinity interaction with γ A /γ′-fibrin(ogen) than γ A /γ A -fibrin(ogen). In contrast, batroxobin binds both fibrin(ogen) isoforms with similar high affinity ( K d values of about 0.5 μm) even though it does not interact with the γ′-chain. The batroxobin-binding sites on fibrin(ogen) only partially overlap with those of thrombin because thrombin attenuates, but does not abrogate, the interaction of γ A /γ A -fibrinogen with batroxobin. Furthermore, although both thrombin and batroxobin bind to the central E-region of fibrinogen with a K d value of 2–5 μm, the α(17–51) and Bβ(1–42) regions bind thrombin but not batroxobin. Once bound to fibrin, the capacity of batroxobin to promote fibrin accretion is 18-fold greater than that of thrombin, a finding that may explain the microvascular thrombosis that complicates envenomation by B. atrox moojeni . Therefore, batroxobin binds fibrin(ogen) in a manner distinct from thrombin, which may contribute to its higher affinity interaction, selective fibrinopeptide A release, and prothrombotic properties. Background: Snake venom protease batroxobin clots fibrinogen in a manner distinct from thrombin. Results: Batroxobin binds fibrin(ogen) with higher affinity than thrombin and promotes greater clot expansion. Conclusion: Batroxobin's distinctive interaction with fibrin(ogen) may contribute to its unique pattern of fibrinopeptide release. Significance: Clinically, batroxobin is used as a defibrinogenating agent, but its capacity to promote clot expansion may promote microvascular thrombosis.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it