THE FLOCCULATION MAXIMUM (pH) OF XXXX AND SOME OTHER BLOOD-CLOTTING REAGENTS. (RELATIVE TURBIDIMETRY WITH THE EVELYN PHOTOELECTRIC COLORIMETER).

@entity2002 @entity598 @entity556
By means of a novel adaptation of the Evelyn photoelectric colorimeter to the measurement of relative turbidities, the question of the flocculation maximum (F.M.) in @entity598 buffer solutions of varying pH and salt content has been studied on (a) an exceptionally stable prothrombin-free @entity2002 and its solutions after incipient thermal denaturation and incomplete tryptic proteolysis, (b) plasma, similarly treated, (c) prothrombin, @entity556 , and (brain) thromboplastin solutions. All the fibrinogens show a remarkable uniformity of the precipitation pattern, viz. F.M. =4.7 (+/-0.2) pH in salt-containing buffer solutions and pH = 5.3 (+/-0.2) in salt-poor buffer (N/100 @entity598 ). The latter approximates the isoelectric point (5.4) obtained by cataphoresis (14). There is no evidence that denaturation or digestion can produce any "second maximum." The data support the view that fibrin formation (under the specific influence of @entity556 ) is intrinsically unrelated to denaturation and digestion phenomena, although all three can proceed simultaneously in crude materials. A criticism is offered, therefore, of W  hlisch's blood clotting theory. Further applications of the photoelectric colorimeter to coagulation problems are suggested, including kinetic study of fibrin formation and the assay of @entity2002 , with a possible sensitivity of 7.5 mg. protein in 100 cc. solution.
