Abstract
It has been reported by many workers that acid-fast bacilli produce large quantities of riboflavin and as it has also been stated that diaphorase, which is considered a flavin enzyme is shown by the murine leprosy bacillus, it was assume that riboflavin would be present in the murine leprosy bacillus but examination of the difference spectrum of cytochromes of murine leprosy bacillus revealed the absence of an absorption band equivalent to riboflavin. In order to clarify this discrepancy, quantitative determinations of riboflavin of murine leprosy bacillus was attempted and noteworthy results were obtained. The lumiflavin method of Yagi et al. was followed, and the riboflavin content of a heated extract of murine leprosy bacilli was measured. The riboflavin content of 1.0g of dried murine leprosy bacillus was 7.5μg and about 1/10 that of rapid grower acid-fast bacilli and about 12.5 that of BCG. The results show that the greater rate of proliferation of the bacillus, the higher was the riboflavin content and the speed of proliferation is in direct proportion to the quantity of riboflavin.
The presence of FAD in the heat extract of murine leprosy bacilli was proven with FAD-free D-amino acid oxidase but quantitative determination was not possible.
Quantitative determination of FAD arid FMN was attempted on an extract prepared with cold TCA according to Bessey's method but FAD could not be found in murine leprosy bacilli though a equal volum to that obtained with the lumiflavin method was verified with acid-fast bacilli grown in the test tube. In other words, the FAD of murine leprosy bacillus is not extractable with cold TCA.
Similar to succinic dehydrogenase, enzyme protein and FAD are firmly bound in this flavin enzyme and the two are not easily separated, and FAD moreover has lost the character of spontaneous oxidation. It is suggested that FAD is present in this form in the murine leprosy bacillus so that it is not extracted by cold TCA and as it is not converted to the oxidized form by aeration in air, it is not revealed in the difference spectrum between oxidation and reduction. It is believed that the electron-transport stops at the stage of flavin enzyme in the murine leprosy bacillus which is lacking in cytochromes. Since the flavin enzyme of murine leprosy bacillus have not the ability of spontaneous oxidation, energy production will not occur so long as there is no mechanism for oxidizing this reduced form of flavin. In order to grow murine leprosy bacillus in vitro, it is believed that a method which will oxidize this reduced form flavin enzyme is required.
