1. This paper deals with the study on the forms of the vitamin B₁₂ in the cells and the supernatant of Lactobacillus leichmannii incubated with cobalamin exogenously supplied. The ratio of DNA to RNA in vitamin B₁₂-starved cells, harvested from a culture on a medium containing deoxyguanosine instead of vitamin B₁₂, was significantly lower than that in normal cells. Incubation of these cells in a medium containing cyanocobalamin or hydroxocobalamin for 5 hours at 37° brought about a remarkable increase of acid-soluble deoxyribosyl compounds, followed by DNA synthesis without an increase of RNA content as well as the bacterial growth.
2. In this case the vitamin B₁₂-active substance detectable in the cells incubated with hydroxocobalamin was identical with that derived from cyanocobalamin, though hydroxocobalamin showed a grear effect than cyanocobalamin on the syntheses of acid-soluble deoxyribosyl compounds and DNA under the experimental conditions. The vitamin B₁₂-active substance present in the cells was extracted with hot 80% ethanol and separated from a contaminating yellow substance by DEAF-cellulose column chromatography. The vitamin B₁₂ contained in the effluent fraction gave a single spot identical with DBCC on paper electrophoresis performed at pH 2.7 and 3.5. Its visible absorption spectrum and the changes by illumination and by cyanide treatment were similar to those of 5, 6-dimethylbenzimidazoylcobamide coenzyme (DBCC). Furthermore; the coenzyme activity of this substance was essentially identical with that of DBCC in the propane diol-propionaldehyde intramolecular oxidation-reduction system of Abeles and Lee when the amounts were calculated on the basis of the absorbancy at 525mμ.
3. The results that DBCC was the sole vitamin B₁₂ in the cells of L. leichmannii in which the formation of deoxyribosyl compounds took place, suggest that the coenzyme is the active form participating in the biosynthesis of deoxyribosyl compounds in the bacteria associated with the finding of Blakley and Barker (9) that DBCC was an only active vitamin B₁₂ stimulating the reduction of ribotide to deoxyribotide in their enzyme system obtained from the bacteria.
DBCC added exogenously, however, showed almost the same effect with hydroxocobalamin. The reason may be attributed to the splitting of the deoxyadenosyl ligand from the coenzyme to be taken up into the bacterial cells.
4. The vitamin B₁₂-active substances in the supernatant derived from hydroxocobalamin were separated by DEAE-cellulose chromatography to an effluent fraction D-1 and a retained fraction D-2. The former behaved analogously to DBCC in paper electrophoresis and in absorption spectrophotometry. The latter, eluted with 0.1 M acetate buffer (pH 4.7), showed the analogous spectroscopic behavior to DBCC as well as D-1, but less cationic character in paper electrophoresis at several pH levels. Both D-1 and D-2 exhibited the coenzyme activity in Abeles-Lee's system, though somewhat smaller than that of DBCC. It remains unsolved whether the activities of these fractions were substantially small or lowered by the contaminating impurities, such as hydroxocobalamin. D-1 seems to be DBCC from its properties. The study on the structre of D-2 is in progress.

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1. A strain of Leuc. mesenteroides was found to secrete an extracellular enzyme revealing formation of riboflavinylglucoside from sucrose and riboflavin.
2. The enzyme was isolated from the cell-free culture fluid of the bacterium grown on a sucrose medium by precipitation with ammonium sulfate and by reprecipitation with acetone.
3. Maximum activity of the enzyme was observed in the range of pH 5.0-5.6 and at 25-30°. The enzyme showed higher stability at 25° and was found to be fairly sensitive to heat as it was destroyed in a few minutes at 40°, even at pH 5.3.
4. It was found that the enzyme revealed high specificity on sucrose, since any other sugars failed to act as the glucosyl donor for the formation of riboflavinylglucoside. Moreover, the enzyme formation was observed only in a sucrose medium.
5. Maltose showed a strong inhibitory effect on the formation of riboflavinylglucoside and Cu²⁺, Fe²⁺ and Fe³⁺ also acted as powerful inhibitors.

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By investigating the reaction of papain with thiamine derivatives of various disulfide types following facts were found.
1. The amount of thiamine formed in the reaction of papain with thiamine propyl disulfide (TPD) or thiamine disulfide (TDS) was nearly equimolar.
2. Remarkable differences were found between asymmetric disulfide compounds of thiamine such as TPD and symmetric ones such as TDS in the inhibitory action on papain, the former being more marked than the latter.
3. Inhibition of papain by TPD or TDS was completely recovered by cysteine.
4. The reaction product of papain with TPD or TDS was investigated by paper chromatography. In the case of TDS, thiamine was detected at the starting point, whereas no thiamine was found in the case of TPD.

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The young albino rats of Wistar strain were fed on a pantothenic acid-deficient diet and in the state of deficiency and in the recovery period by supplementing with D-calcium pantothenate or DL-panthenol the change in body weights was studied. Further, the contents of free pantothenic acid were measured by microbioassay using L. arabinosus and of CoA by enzymatic formation of sorbyl-CoA. Both free pantothenic acid and CoA were reduced at the end of 3 week deficiency, the free values becoming almost 0. In the recovery state after receiving pantothenate or panthenol the levels of the free vitamin of both groups were somewhat higher than that of the control group, but the contents of CoA in organs were recovered almost to those of the control group. No difference between the two groups receiving pantothenate and panthenol was found.

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1. The enzymatic reduction of dehydro-L-ascorbic acid in Escherichia coli was reported at the physiological pH range with the assay condition without loss of resulting ascorbic acid.
2. The enzyme, dehydroascorbic acid reductase, was partially purified, and some properties were observed. Hydrogen donors, hydrogen acceptors, and cofactor requirement were studied.

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1. The cell-free extracts of soy bean seedlings contained an enzyme system which converted some pteridines, p-aminobenzoic acid and glutamic acid to the compounds active for S. faecalis R (ATCC No. 8043) in the presence of ATP and Mg²⁺. The pteridines used in the formation of folate-active compounds were 2-amino-4-hydroxy-6-hydroxymethyltetrahydropteridine and 2-amino-4-hydroxy-6-formylpteridine.
2. The partially purified enzyme system obtained from spinach leaves catalyzed among the tested pteridines most effectively the coupling reaction of 2-amino-4-hydroxymethyldihydropteridine with p-aminobenzoic acid to yield dihydropteroic acid and with p-aminobenzoylglutamic acid to form dihydrofolic acid. This reaction was dependent upon ATP and Mg²⁺.
3. p-Aminobenzoic acid was more effective as the substrate for dihydropteroic acid synthesis than p-aminobenzoylglutamic acid for dihydrofolic acid.
4. In the coupling reaction of 2-amino-4-hydroxy-6-hydroxymethyldihydropteridine with p-aminobenzoic acid to yield dihydropteroic acid, the dihydropteridine seemed to be firstly activated by ATP and then condensed with p-aminobenzoic acid.
5. General properties of dihydropteroic acid-synthesizing enzyme system were described.

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1. Reduction of the glucose amount in the MaciasR medium for thiamine assay using Lactobacillus fermenti 36 to half the amount (20mg per tube) resulted in the maximal growth of the bacterium after 18-hour incubation. Glucose more than 20mg per tube was not utilized, but it rather inhibited the growth of the bacterium.
2. Exchange of glucose with fructose or maltose in the MaciasR medium failed to show the better growth.
3. Xylose was not effective in place of glucose, but it has a growth-promoting activity on the bacterium in addition to glucose.
4. The growth-promoting effect of xylose was not specific. Ribose showed a rather greater effect than xylose on the growth, but other pentoses had no growth-promoting effect.

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1. Yeast alcohol dehydrogenase activity is inhibited by incubation at pH 6-8 with several thiamine disulfide derivatives and the inhibition is partially reversed by addition of cysteine.
2. Inhibition by thiamine disulfide derivatives increases with the rise of concentration and pH. The inhibition by asymmetric thiamine disulfide derivatives is stronger than that by symmetric thiamine disulfide derivatives. It was proved by paper chromatography that the enzyme was bound with the thiamine moiety of thiamine disulfide or the propylmercaptan moiety of of thiamine propyl disulfide in the reaction of the enzyme with both disulfides but no thiamine was detected from the enzyme protein after the reaction of the enzyme with thiamine propyl disulfide.

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Both thiamine propyl disulfide (TPD) and S-carbethoxythiamine (CET) stimulate the growth of K. apiculata but they show the following different behaviors.
1. When CET is reduced to thiamine extracellularly by Takadiastase, it shows the same activity as thiamine on the growth of the bacterium.
2. When TPD is reduced to thiamine by cysteine extracellularly, it shows the activity greater than thiamine.
3. When TPD accumulated in the cells in saline are diluted with the medium and incubated, they show the same activity as thiamine, but when CET is treated in the same way, it showes the activity greater than thiamine.
4. TPD is easily reduced to thiamine in the presence of the yeast suspension but CET is slowly converted to thiamine on the same treatment.

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1. The synthesis of D-ribose from D-erythrose by cyanohydrin reaction was carried out.
2. The product formed in largest quantity from D-erythrose has an arabonic configuration under the original conditions of Kiliani and Fischer (1).
3. The result of paper chromatography with use of a solvent system, isopropanol-water (6:1) revealed that D-ribonic lactone moved faster than D-arabonic lactone.
4. The crude D-ribose obtained by reduction of D-ribonic lactone was purified with use of cellulose column chromatography according to Hough et al. (12).

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