Question

station 24.

1. name the bacterial enzyme that completes the following reaction:

prothrombin→fibrin

1. name the substrate from the positive test below:

Explanation:

Question 47

In the coagulation process, the enzyme that converts prothrombin to fibrin (actually, prothrombin is converted to thrombin first, and thrombin converts fibrinogen to fibrin; but if we consider the reaction as written, the bacterial enzyme that can mimic this or be involved in a similar reaction (like in some bacterial infections affecting coagulation) or the enzyme related to the conversion (maybe a mis - phrased question, but the key enzyme for prothrombin to thrombin is prothrombinase, but if we assume the reaction is prothrombin to fibrin (ignoring the intermediate thrombin and fibrinogen step for the question's sake), or maybe the question has a typo and it's fibrinogen. However, the bacterial enzyme that can act on prothrombin - like staphylocoagulase (from Staphylococcus aureus) which can convert prothrombin to thrombin (and then thrombin converts fibrinogen to fibrin). So the bacterial enzyme here is coagulase (specifically staphylocoagulase) which helps in the coagulation - like reaction by acting on prothrombin.

Since the positive test is likely a coagulase test (related to the previous question about bacterial enzyme acting on prothrombin), in the coagulase test, the substrate is prothrombin (or in the normal coagulation cascade, the substrate for thrombin (which is produced from prothrombin) is fibrinogen, but if the test is a coagulase test, the substrate is prothrombin - containing plasma (so the substrate is prothrombin or plasma with prothrombin). Given the context of the previous question about bacterial enzyme acting on prothrombin, the substrate in the positive test (coagulase test) is prothrombin (or plasma that contains prothrombin).

Answer:

Coagulase (e.g., Staphylocoagulase)

Question 48