The use of potassium cyanide in the lactobacillus leichmannii assay for vitamin B12.
نویسندگان
چکیده
Studies by several investigators (Stokstad, Dornbush, Franklin, Hoffmann, Hutchings, and Jukes, 1949; Skeggs, Nepple, Valentik, Huff, and Wright, 1950) have indicated that an increased growth response was obtained to liver concentrates with thioglycolic or thiomalic acids when vitamin B12 activity was determined with Lactobacillus leichmannii. This was attributed to the prevention, by such reducing agents, of the destruction of vitamin B12 in tl L. leichmannii assay mediuam. Recently Hendlin and Soars (1951) have shown that it is vitamin B12. which is readily destroyed when autoclaved in the assay medium and that such destruction is prevented either by aseptic addition of the sample to sterile medium or by addition of reducing substances. Vitamin B12 was unaffected under these conditions. Brink, Kuehl, and Folkers (1950) have reported that vitamin B12 is a cyano-cobalamin complex; and Kaczka, Wolf, Kuehl, and Folkers (1950) have demonstrated that vitamin B12. differs from vitamin B12 by the absence of the cyano group. Furthermore, vitamin B12a could be converted to vitamin B12 by reaction with potassium cyanide. It appeared likely, on the basis of the foregoing data, that the assay of liver concentrates and other substances in a potassium cyanide supplemented medium would result in the conversion of vitamin B12. like components to the more stable vitamin B12, thus eliminating the use of reducing agents. This would be a definite advantage since the reducing agents themselves elicited a response from L. lichmannii. The experimental data presented here substantiate this hypothesis.
منابع مشابه
Extraction of serum vitamin B12 for radio-isotopic and Lactobacillus leichmannii assay.
The protein precipitates discarded during the extraction process of the Lactobacillus leichmannii vitamin B12 assay have been shown to contain significant amounts of vitamin B12. This loss of vitamin B12 provide a satisfactory explanation for many of the descrepancies between the serum vitamin B12 values obtained by the L. leichmannii method and the radio-isotopic method of Raven et al (1969). ...
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عنوان ژورنال:
- Journal of bacteriology
دوره 62 1 شماره
صفحات -
تاریخ انتشار 1951