Specificity of glucose oxidase (notatin)

Abstract

ASSAY OF B VITAMINS USING L. CASEI 331 recent methods, that described by Kodicek & Pepper (1948b) had been in use in this laboratory, but the present medium with L. casei has completely replaced the former procedure and was found to give more satisfactory results.In the assay of pteroylglutamic acid the con- jugates, with the exception of Teropterin, showed an activity in general agreement with the findings of other workers.SUMMARY 1.An improved medium was developed for the assay of pteroylglutamic acid with Lactobacillus casei and was tested for some other B vitanins and tryptophan.2. The titrimetric dose-response curves for ribo-flavin, nicotinic acid, calcium pantothenate, biotin and tryptophan were satisfactory.3. The medium has been used in particular for the microbiological assay of total nicotinic acid, and the results were in good agreement with the chemical values.The bound form of nicotinic acid present in cereals was found to be less active than the free vitamin.4. A number of conjugates of pteroylglutamic acid and other pteridines were tested.We wishtothankDrA.Albert for the synthetic pteridines, Dr T. H. Jukes for pteroylgutamic acid and conjugates, Dr J. J. Pfiffnerfor the vitamin B. conjugate, Dr L. D. Wright for the biocytin concentrate, Dr K. Folkers for biotin and rhizopterin, and the Flour Millers Association for the supply of the different brans.