1. It is observed that the isometric contraction of the glycerol-treated fiber in a bath containing ATP and Mg⁺⁺ is reversed to a considerable extent by mere washing, while the fiber contracted under isotonic conditions remains shortened upon washing.
2. A previous report (4) has stated that the fiber relaxed in a bath of EDTA, ATP and Mg⁺⁺ can be made to contract upon addition of Cd⁺⁺ or Zn⁺⁺, but that the fiber relaxes again spontaneously when the concentration of Cd⁺⁺ or Zn⁺⁺ added exceeds that of the EDTA present. In contrast with these observations under isometric conditions, the second relaxation by Cd⁺⁺ or Zn⁺⁺ is not observed.
3. The pyrophosphate relaxation of the fiber under isometric conditions requires a concentration of pyrophosphate much lower and proceeds faster than that under isotonic conditions.
4. The cysteine-lengthening of the fiber under isotonic conditions can be stopped by addition of Cd⁺⁺ or Zn⁺⁺. The fiber thus ceased its lengthening retains the full recontractility.
5. A discussion is made on a temporary suggestion of the cross-linkage formation in the fiber under isotonic conditions.

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1. The current work was carried out, using C¹⁴ glucose, to examine whether α-ketoglutaric acid, oxalacetic acid, and glyoxylic acid are synthesized from the glucose in the silkworm. Three kinds of keto acid were respectively isolated from the body fluid of silkworms which consumed C¹⁴ glucose as their 2, 4-dinitrophenylhydrazones, and their radioactivities were measured.
2. High radioactivity was recognized in α-ketoglutaric acid and in oxalacetic acid, but the radioactivity of glyoxylic acid was extremely low, showing that glucose is not a direct precursor for glyoxylic acid.
3. It seems to be doubtful that the formation of glyoxylic acid from glucose is the main pathway for glyoxylic acid synthesis.

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1. An attempt has been made to compare the behaviours of nicotinic acid in rabbit, domestic fowl, tortoise and frog by the chromatographic techniques.
2. The rabbit, fowl, tortoise, and frog converts nicotinic acid into nicotinamide, which is partly methylated into N¹-methylnicotinamide in rabbit, tortoise, and frog except fowl showing quantitative difference and other part of it is oxidized to N¹-methyl-6-pyridone-3-carboxamide in rabbit.
3. In fowl, nicotinic acid seems to be conjugated with ornithine into nicotinoyl-ornithine-like substance, while in rabbit, tortoise and frog it is conjugated with glycine.
The author wishes to express his cordial thanks to Dr. M. Tomita for his con-tinuous advice and encouragement.

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1. The protein fraction which catalyzes pyridoxine oxidation in the presence of aldehyde oxidase preparation was purified from rabbit liver extracts.
2. The pyridoxine oxidizing enzyme system showed the highest activity at pH 5.7 to 5.9.
3. The ability of Fraction PO to oxidise pyridoxine was dependent on the presence of aldehyde oxidase preparation from rabbit liver.
4. The pyridoxine oxidizing activity in the crude extracts was enhanced by the addition of ferrous ion, manganese ion and some aliphatic alcohols. The stimulatory action of these metal ions was not observed with a purified preparation.
5. 4-Deoxypyridoxine competitively inhibited the oxidation of pyridoxine.
6. No electron acceptor in this reaction could be identified in the liver system. However, a preliminary experiment with the yeast enzyme revealed a requirement for TPNH in the conversion of pyridoxal to pyridoxine.
7. The distribution of the pyridoxine oxidizing activity was studied in several mammalian tissues.

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1. Pyridoxine phosphate oxidase was purified from a rabbit liver extract.
2. The oxidase was most active at pH 8.0 to 9.0.
3. 4-Deoxypyridoxine phosphate competitively inhibited the oxidation of pyridoxine phosphate.
4. The oxidase was resolved from its prosthetic group by treatment with acidic ammonium sulfate. The apo-oxidase showed higher affinity for FMN than for FAD.
5. Stoichiometry of the reaction was studied in a sonic extract of Pseudomonas aeruginosa. The result supported the following reaction mecanism:
Pyridoxine phosphate+O₂_??_Pyridoxal phosphate+H₂O
6. The distribution of the enzyme activity was studied in several mam-malian tissues and Streptococcus faecalis. In the latter pyridoxine phosphate oxidase seems to be absent.

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1. The absorption spectra of crystalline turnip peroxidase D were measured for its alkaline form and for its compounds with carbon monoxide, cyanide, azide and fluoride. They were found to agree very closely with those of horseradish peroxidase. The pK value of the dissociation of a hydrogen ion from the water molecule linked to the iron atom of hematin was found to be 10.28 at an ionic strength of 0.1.
2. The diffusion constant (D_{20, W}) of the enzyme was found to be 8.37×10^-7cm². sec^-1.
3. The sedimentation constant (S_{20, W}) of the enzyme was found to be 3.58 S or 3.55 S, assuming the partial specific volume to be 0.75 or 0.70, respectively.
4. Using the above values, the molecular weight was calculated to be 41, 500 or 34, 300 and the frictional ratio 1.10 or 1.23, respectively.
The author wishes to express his sincere thanks to Prof. N. Ui for his invaluable advice and encouragement. This study was aided in part by a Grant-in-Aid for Scientific Research from the Ministry of Education given to the Research Group on “Mechanism of Enzyme Action”.

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1. The antibodies responsible for insulin neutralization were induced in guinea pigs by injection of insulin in complete Freund's adjuvant.
2. The adjuvant effect of tubercle bacilli on production of neutralizing antibodies for insulin seems to depend mainly on Wax D fraction.

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1. The inducible presence of DPNH-nitrate reductase of sulfhydryl CO-insensitive metalloenzyme nature in the large particles from nitrate grown Azotobacter cells was described. The activity was stimulated 1.5- to 2-fold by externally added FAD or FMN. Small activity of DPNH-hydroxylamine reductase was also found to reside in the same particles, while DPNH-nitrite reductase activity was never found.
2. Reduced nile blue was shown to be a most effective electron donor with 2- to 3-fold increase in the reaction rate from that of DPNH-nitrate reductase. The reduced nile blue-nitrate reductase activity was unaffected by FAD, FMN and p-chloromercuribenzoate.
3. In contrast to DPNH oxidase in the large particles, DPNH-nitrate reductase has no participation of cytochrome components bound to the particles, though the latter system was inhibited by oxygen.
4. The scheme of electron-transferring sequence leading to nitrate apparently of nitrate assimilation type was presented.
5. The particulate nitrate reductase had Km of 5.3×10^-4M for enzyme-nitrate complex and pH optimum at 6.7.
6. The presence of pyridine nucleotide-nitrite and hydroxylamine reductase of significant activites in the soluble cytoplasmic fraction was confirmed.
7. DPNH and succinate oxidases activities of the large particles were suppressed by culturing the cells on nitrate as a sole nitrogen source, these were, however, still far stronger than DPNH-NaR activity.
8. An aerobic system metabolizing nitrate and nitrite with simultaneous oxidation of glucose was found in nitrate grown Azotobacter cells. The aerobic system is far more active than the anaerobic one suggesting a more direct participation of the aerobic system in nitrate assimilation of this aerobe.
The authors are greatly indebted to Prof. F. Egami, Drs. S. Hino and H. Takahashi for support of this investigation and their valuable criticism. Gratitude is also expressed to Prof. Mori who kindly helped our spectroscopic observations of cytochromes. This research was supported in part by a grant from the Scientific Research Fund of the Ministry of Education.

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1. Tuberculin-active protein, hC, was dinitrophenylated with DNFB, but the tuberculin activity was not affected even after half of the lysine residues and all of the tyrosine residues were blocked by this reagent.
2. When PABC was reacted with hC, 27 PAB-residues was introduced into 10⁵g. of protein. Tuberculin activity remained unchanged after this treatment.
3. No N-terminal amino acid was found in hC by means of the DNP-method.
The anther wishes to thank Prof. S. Akabori, Osaka University, for his continuous interest and advice during the course of this investigation, and to thank Prof. Y. Yamamura, Kyushu University, for his encouragement and guidance. The author also wishes to thank Dr. K. Ogura, Toneyama National Sanatorium, for his helpful advice, especially on the skin test technique.

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A study to investigate the ability of liver to synthesize serum γ-globulin has been made by the detection of its net production with an application of the quantitative precipitin reaction. The following results have been obtained:
1. The liver slice, when incubated in a medium of salt mixture, could produce 136±7.6μg. of γ-globulin in 2 hours per g. of wet weight of liver. This net production was enhanced by using acid hydrolysates of plasma proteins as a medium and markedly reduced by adding several metabolic inhibitors to the medium.
2. The homogenate could not reproduce this activity under the same condition as in the case of the slice, but it was almost recovered by fortifi-cation with ATP at a final concentration of 3.5×10^-3M.
3. With use of various subcellular fractions prepared by differential centrifugation, it was demonstrated that the microsomes, in combination of the supernatant fraction, retained about 70 per cent of the activity compared to the whole homogenate, and the particulate fractions alone showed no detectable net production.
4. In the deoxycholate soluble system which consisted of the deoxycholate soluble components derived from the particulate fractions, TCA or PCA soluble factors of the supernatant fraction and ATP, authors have demonstrated the net production of γ-globulin, though to a limited extent.
5. In this soluble system, active proteins in deoxycholate extracts were able to be salted out with between 10 and 20 g./dl. of ammonium sulfate solution, and RNase inhibitors, although unknown, were indicated as one of the important factors involved in the deproteinized supernatant. Compared to ATP, GTP was found more efficient.
The authors wish to express their heartful gratitude to Prof. N. Shimazon o and Associate Prof. H. Hirai for their continuous encouragements and interest during the course of this work. Their thanks are also due to Mrs. S. B. Blume for her kind advices to complete this mamuscript.

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1. Partially purified insulin from Langelhans islet of bonito, was separated on a column of CM-cellulose into two components having full insulin-activity; and that the one had one glycyl and one leucyl chains, while the other had one glycyl and one alanyl chains per 6×10³g. as the N-terminals, respectively.
2. It was described some evidences that the leucyl and alanyl chains present in bonito insulins I and II, corresponded to the phenylalanyl chain in mammalian ones, and some differences observed between the properties of both insulins from fish and from mammal seemed to be mainly due to the difference of the both glycyl chains.
The authors are greatly indebted to the Shimizu Seiyaku Co., Ltd., for the gifts of various kind of insulin. This study was in part supported by a grant-in-aid from the Ministry of Education.

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Chemical structure of FFC was studied. The components of FFC were determined to be equimoles of riboflavin and phosphoric acid. Considering the previous result that FFC has not a second dissociation, of phosphate group, the chemical structure was supposed to be riboflavin cyclic phosphate. Then, periodate consumption was estimated, and it was found that one mole of periodate was consumed per one mole of isoalloxazine nucleus of FFC. The periodate oxidation product of FFC was analyzed. When this product was oxidized by bromine water, it gave 6, 7-dimethyl-isoalloxazine-9-actic acid, methyl ester of which was further identified with 6, 7-dimethyl-isoalloxazine-9-acetic acid methyl ester. Thus, the periodate oxidation product was found to be 6, 7-dimethyl-isoalloxazine-9-acetaldehyde. From these results, the cleavage of ribitol chain of FFC by periodate oxidation was found to take place between C₂' and C₃'. Consequently, the structure of FFC was identified with riboflavin-4', 5'-cyclic phosphoric acid which had been found by Forres t and Todd in the solution of FAD treated with concentrated ammonia.

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1. From the pupae of the silkworm, Bombyx mori, an enzyme which specifically hydrolyzes trehalose, has been purified.
2. Chromatographic procedure has revealed the existence of two forms of trehalase, but their properties did not differ as fas as trehalose hydrolysis is concerned.
3. In a larval stage, trehalase activity is found in intestine, body-wall muscle, and fat body, but not in body fluid and silk gland.
The author wishes to express his gratitude to Prof. Y. Akita and Assist. Prof. M. Akino for their guidance and criticism throughout this work. Thanks are also due to Prof. K. Dan for reading the manuscript.

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1. When each of glucose, acetate, pyruvate, oxaloacetate, and succinate was incubated aerobically with the washed cell suspension of Brevibacterium flavum No. 2247 in the presence of C¹⁴O₂, labelled glutamate and α-ketoglu-tarate were obtained in all cases. The specific activities of these acids were far greater with glucose than that with other substrates. The carbon atom of the α-carboxyl group of glutamate thus formed had a specific activity about 100 times as great as the average of that found in the other carbon atoms.
2. With the cell-free extract of this bacterium incorporation of a considerable amount of C¹⁴ from C¹⁴O₂ into oxaloacetate and L-malate was observed. The incorporation into oxaloacetate was stimulated by the addition of inosine triphosphate and manganous ion, and that into L-malate by the addition of triphosphopyridine nucleotide and manganous ion, suggesting bothh the oxaloacetic carboxylase of Utter and Kurahashi and the malic enzyme of Ochoa to be involved in the C¹⁴O₂ fixation.
3. On the basis of the relative rates of incorporation of C¹⁴ into pools of malate and oxaloacetate, it was concluded that the incorporation of CO₂, into oxalocetate did not involve malate as intermediate.
The authors are indebted to Dr. H. Oeda and Mr. N. Motozaki of our laboratory for their interest and encouragement during the course of this work. The authors also thank Dr. T. Yamada and Prof. F. Egami of the University of Tokyo and Prof. S. Akabori of the Osaka University for many helpful discussions and advices.

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1. Urocanase was partially purified from Pseudomonas aeruginosa and from cat liver, measuring urocanase activity by CPIP reduction.
2. The pH optimum of the urocanase was found to lie between pH 7.0 and 8.0 in both enzyme preparations. Effects of some inhibitors on urocanase were studied.
3. Imidazolonepropionic acid, a proposed early intermediate in urocanate metabolism, is thought to be the starting substrate for the oxidation.
4. The oxidation was completely inhibited by catalase, and stimulated by some metals. A lag period in the oxidation was eliminated by the addition of a small amount of hydrogen peroxide. The mechanism of the oxidation is discussed.
5. One group of oxidation products of urocanic acid includes α-keto-glutaric acid amide, formic acid and ammonia. Another is represented by some carbamyl derivatives or their precursor. The occurrence of these compounds in the incubation mixture was demonstrated using urocanic acid-2-C¹⁴.
Before this paper was submitted to press, papers of Brown and Kies have appeared (28). They claim that hydantoinpropionic acid arises from imidazolonepropionic acid.

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The substrate specificity of purified Taka-maltase I was studied. The relative rates of hydrolysis of Taka-maltase I on maltose, α-methyl-D-glucoside, α-phenyl-D-glucoside, α-methyl-maltoside and α-phenyl-maltoside were 1, 0.0048, 0.092 0.0096 and 0.54, respectively. Amylose, sucrose, raffinose, trehalose, cellobiose and lactose were not attacked by this enzyme.
Taka-maltase I also showed the transglucosylase activity. Downward mutarotation of glucose produced by hydrolysis of maltose by this enzyme was observed.
The author wishes to express his gratitude to Prof. S. Akabori for his kind guidance throughout the study, and also wishes to thank the Sankyo Co. Ltd. for their kind supply of “Takadiastase Sankyo”.

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