Clotting and Anticlotting Substances
If it is true, as has already been urged, that increases in protoplasmic viscosity are in large measure due to a clotting reaction similar in many respects to the clotting reaction that occurs in vertebrate blood, then it might be expected that substances which clot vertebrate blood would act in the same way on protoplasm, and substances which prevent the clotting of vertebrate blood would tend to keep the protoplasm fluid. In vertebrate blood, as is now well known, clotting is due to the action of a calcium-activated proteolytic enzyme, thrombin, on the protein fibrinogen. Other proteolytic enzymes, such as trypsin, can also cause blood to clot. (There are many recent reviews on various phases of the blood clotting process; see for example Lorand 1954.)
KeywordsProteolytic Enzyme Nitrogen Mustard Potassium Cyanide Opposite Fashion Vertebrate Blood
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