Abstract
PROF. R. H. HOPKINS1 has added to Dr. Barton Wright's and Mr. Booth's2 reply to the comments made by Happold3 on the microbiological technique for the assay of riboflavine and has included a criticism of the work published by us4. Both communications concentrate on the point made by us regarding the amount of calcium in the medium, while ignoring other points of criticism which we made. Barton Wright and Booth state that the calcium effect is due to buffer action, this being incorrect, while Hopkins, relying on the papers of Holt, La Mer and Chown5 on calcification in bone and on the solubility product of Ca3(PO4)2 in water or in serum, states that the calcium concentration could not be influenced appreciably by added calcium chloride at pH 6.6–6.8. It should be mentioned that Holt et al. state that the solubility product is affected enormously by the presence, of other salts and that a complex solution of amino-acids is very different from serum (protected by these workers against bacterial proteolysis). They also state "the precipitation of tertiary calcium phosphate occurs so slowly that solutions of this salt may remain supersaturated for many days".
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References
Hopkins, R. H., NATURE, 152, 724 (1943).
Barton Wright, E., and Booth, R. G., NATURE, 152, 414 (1943).
Happold, Frank C., NATURE, 152, 414 (1943).
Chattaway, F. W., Happold, F. C., and Sandford, M., Biochem. J., 37, 298 (1943).
Holt, E., La Her, V. K., and Chown, H. C., J. Biol. Chem., 64, 509 (1925).
Mueller, J. H., Klise, K. S., Porter, E. F., and Graybiel, A., J. Bact., 25, 509 (1933).
Strong, F. M., and Snell, E. E., Ind. Eng. Chem., Anal, ed., 11, 346 (1939).
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HAPPOLD, F., CHATTAWAY, F. & SANDFORD, M. Microbiological Assay of Riboflavine. Nature 153, 225–226 (1944). https://doi.org/10.1038/153225b0
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DOI: https://doi.org/10.1038/153225b0
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