Abstract
The nature of the substance in filtrates of whole blood and plasma which gives the color with alkaline picrate (Jaffe's reaction) has been for many years a subject of controversy. One group of investigators believe that this material is true creatinine—others deny that creatinine exists in normal blood. Because of the non-specific methods employed for the identification of creatinine, and the very minute quantities of the chromogenic material available in normal blood, it has been difficult for either group to present convincing evidence.
To obtain a definitive answer regarding the nature of the Jaffe-reactive material in blood, and also to develop a specific method for the analysis of creatinine in biological fluids, an attempt was made to obtain a specific enzyme for creatinine. By means of a technique similar to that described by Dubos and Avery 1 and Dubos 2 it has been possible to isolate 4 different species of soil bacteria with a high degree of adaptability toward a substrate of creatinine. One strain (NC) has been found to grow with unusual ease in a medium of pure creatinine and inorganic salts. When tested under conditions which do not allow cellular multiplication, the bacterial suspension still decomposes creatinine very readily. The enzyme seems to be intimately associated with cellular structure and so far has not been released into solution without destroying its activity. However, when the cells of another bacterial species (HR) are disrupted, the creatinine decomposing enzyme is readily obtained in aqueous solution. At present, the potency of this soluble preparation is low compared with a cell suspension of the NC organisms.
The present crude enzyme preparation (NC) will decompose its own weight of creatinine in 15 minutes at 37° C. and pH 7.0.
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