L-glycerol 3-phosphate Dehydrogenase Research Articles

Enzyme architecture: optimization of transition state stabilization from a cation-phosphodianion pair.

The side chain cation of R269 lies at the surface of l-glycerol 3-phosphate dehydrogenase (GPDH) and forms an ion pair to the phosphodianion of substrate dihydroxyacetone phosphate (DHAP), which is buried at the nonpolar protein interior. The R269A mutation of GPDH results in a 110-fold increase in Km (2.8 kcal/mol effect) and a 41 000-fold decrease in kcat (6.3 kcal/mol effect), which corresponds to a 9.1 kcal/mol destabilization of the transition state for GPDH-catalyzed reduction of DHAP by NADH. There is a 6.7 kcal/mol stabilization of the transition state for the R269A mutant GPDH-catalyzed reaction by 1.0 M guanidinium ion, and the transition state for the reaction of the substrate pieces is stabilized by an additional 2.4 kcal/mol by their covalent attachment at wildtype GPDH. These results provide strong support for the proposal that GPDH invests the 11 kcal/mol intrinsic phosphodianion binding energy of DHAP in trapping the substrate at a nonpolar active site, where strong electrostatic interactions are favored, and obtains a 9 kcal/mol return from stabilizing interactions between the side chain cation and transition state trianion. We propose a wide propagation for the catalytic motif examined in this work, which enables strong transition state stabilization from enzyme–phosphodianion pairs.

Restoring a metabolic pathway.

Gluconeogenesis is blocked in a strain of Escherichia coli that is deficient in triosephosphate isomerase, but it was restored by the insertion of a plasmid coding for an L-glyceraldehyde 3-phosphate reductase (YghZ). This reductase provides a "bypass" that produces dihydroxyacetone phosphate (DHAP) by the consecutive enzyme-catalyzed reduction of L-glyceraldehyde 3-phosphate ( L-GAP) by NADPH to give L-glycerol 3-phosphate and reoxidation by NAD(+) catalyzed by endogenous L-glycerol 3-phosphate dehydrogenase to give DHAP. The origin of cellular L-GAP remains to be determined.

Fermentative production of l‐glycerol 3‐phosphate utilizing a Saccharomyces cerevisiae strain with an engineered glycerol biosynthetic pathway

Interest in L-glycerol 3-phosphate (L-G3P) production via microbial fermentation is due to the compound's potential to replace the unstable substrate dihydroxyacetone phosphate (DHAP) in one-pot enzymatic carbohydrate syntheses. A Saccharomyces cerevisiae strain with deletions in both genes encoding specific L-G3Pases (GPP1 and GPP2) and multicopy overexpression of L-glycerol 3-phosphate dehydrogenase (GPD1) was studied via small-scale (100 mL) batch fermentations under quasi-anaerobic conditions. Intracellular accumulation of L-G3P reached extremely high levels (roughly 200 mM) but thereafter declined. Extracellular L-G3P was also detected and its concentration continuously increased throughout the fermentation, such that most of the total L-G3P was found outside the cells as fermentation concluded. Moreover, in spite of the complete elimination of specific L-G3Pase activity, the strain showed considerable glycerol formation suggesting unspecific dephosphorylation as a mechanism to relieve cells of intracellular L-G3P accumulation. Up-scaling the process employed fed-batch fermentation with repeated glucose feeding, plus an aerobic growth phase followed by an anaerobic product accumulation phase. This produced a final product titer of about 325 mg total L-G3P per liter of fermentation broth.

Effect of hexachlorobenzene on NADPH-generating lipogenic enzymes and L-glycerol-3-phosphate dehydrogenase in brown adipose tissue.

The effect of the in vivo administration of hexachlorobenzene (HCB) (100 mg/100 g bw) for 30 days, on the activities of brown adipose tissue (BAT) lipogenic enzymes, i.e. malic enzyme (ME), and glucose-6-phosphate dehydrogenase (G6PD) and the mitochondrial non lipogenic enzyme, L-glycerol-3-phosphate dehydrogenase (LG3PD), was studied in male Wistar rats, submitted to various neurohormonal manipulations. BAT ME, G6PD and LG3PD activities showed significant reductions in response to HCB treatment both in euthyroid and surgically thyroidectomized rats, showing that the effect does not depend on the presence of thyroid hormones. These results differ from those obtained for hepatic ME and G6PD activities, which increased in HCB intoxicated rats without alteration in LG3PD. HCB decreased BAT ME activity under BAT denervation. Administration of HCB resulted in time and dose-dependent decreases in the activity of BAT malic enzyme. The basal activity of ME was increased in hypothyroid rats, while that of LG3PD was reduced. A stimulatory effect of receptor-saturating doses of triiodothyronine (T3) (50 microg/100 g body weight) was observed on BAT ME and LG3PD activities in thyroidectomized rats, showing that the enzymes responded to thyroid hormone stimulation in a normal manner. The stimulatory effect of saturating doses of T3 on ME and LG3PD was reduced by HCB. The results presented herein unequivocally show that brown adipose tissue is a specific target in HCB-induced toxicity, which in turn involves severe alterations in the regulation of BAT lipogenesis.

Mitochondrial oxidative enzyme activity in individual fibre types in hypo- and hyperthyroid rat skeletal muscles.

Quantitative cytochemical and biochemical techniques have been used in combination to study the response of mitochondrial oxidative enzymes in individual muscle fibre types to hypo- and hyperthyroidism. Hypothyroidism resulted in decreased activity of succinate dehydrogenase (SDH), L-glycerol-3-phosphate dehydrogenase (L-GPDH), and D-3-hydroxybutyrate dehydrogenase (D-HBDH) in all fibre types of both slow-twitch soleus and fast-twitch extensor digitorum longus (e.d.l.) muscles. In hyperthyroidism, only L-GPDH activity increased in e.d.l. but more marked increases were seen in soleus muscles, which also showed increased SDH activity. In addition to these alterations in the enzyme activity in individual fibre types the metabolic profile of the muscle is further modified by the hormone-induced interconversion of slow- to fast-twitch fibres and vice versa.

Partial purification and properties of respiratory chain-linked l-glycerol 3-phosphate dehydrogenase from a marine bacterium, Vibrio alginolyticus.

Respiratory chain-linked L-glycerol 3-phosphate (G3P) dehydrogenase [EC 1.1.99.5] of marine bacterium, Vibrio alginolyticus, was extracted from the membrane fraction by treatment with Tween 20, and fractionation on DEAE-Sephacel and QAE-Sephadex in the presence of 0.05% Liponox DCH(alkyl polyoxyethylene ether) yielded a preparation having a specific activity of 22.1 units/mg protein when assayed by phenazine methosulfate (PMS)-coupled reduction of thiazolyl blue tetrazolium (MTT). The purified enzyme had an apparent molecular weight of 300,000 as determined by chromatography on Sepharcyl S-300 in 0.05% Liponox DCH, and had noncovalently bound FAD as its coenzyme. The enzyme had a pH optimum of 8.5-9.0, and required 200 mM NaCl or KCl and an appropriate detergent (such as Tween, Brij or Liponox DCH) for maximum activation. The activating effect of NaCl was due to a decrease in Km for G3P and that of Tween 20 was due to both a decrease in Km and an increase in Vm. Triton X-100 could not activate the enzyme and was inhibitory in the presence of phospholipids. The reaction followed a ping-pong mechanism. IN addition to PMS, 2,6-dichlorophenol indophenol and duroquinone, the enzyme could reduce ubiquinone-5 (Q-5) in the presence of Liponox DCH at a rate of 46% of the PMS reductase activity. The enzyme was strongly inhibited by heavy metal ions and by p-chloromercuribenzoate. The activity for Q-5, but not for PMS, was inhibited by o-phenanthroline and bathophenanthroline, suggesting the participation of nonheme iron protein in the Q-5 reduction.

NAD +-specific glycerol 3-phosphate dehydrogenase from developing castor bean endosperm

l-Glycerol 3-phosphate dehydrogenase has been isolated and partially purified from the endosperm of developing castor beans. The enzyme is entirely cytosolic and is not found in the plastid fraction. No activity was found in germinating castor beans. The pH optimum for the reduction of dihydroxyacetone phosphate is 8.1 and is 9.6 for the reverse reaction. The molecular weight determined by gel filtration chromatography is between 71,000 and 83,000. Both substrates show substrate inhibition at concentrations about 13 μ m for NADH and 400 μ m for dihydroxyacetone phosphate. Substrate interaction kinetics gave limiting K m values of 2.7 and 35.5 μ m for NADH and dihydroxyacetone phosphate, respectively. Substrate interaction and product inhibition kinetics were consistent with an ordered sequential mechanism with NADH being the first substrate to bind and NAD + being the last product to dissociate.

Flow of reducing equivalents into isolated intestinal mitochondria

A system of enzymes is required for the transport of reducing equivalents from reduced nicotinamide adenine dinucleotide (NADH) generated in the cytosol into the mitochondria by the substrate cycles. Also, the intestinal mitochondria must be capable of oxidizing the substrates of the cycles. Both substrate cycle enzymes and permeable mitochondria are necessary for the flow of pyruvate derived from glucose into the mitochondria for oxidative decarboxylation and for the efficient production of adenosine 5′-triphosphate (ATP) for the unique intestinal nutrient transport functions. Mitochondria from hamster intestinal mucosa were prepared exhibiting good respiratory control ratios. The isolated intestinal mitochondria would not oxidize NADH unless N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) was added as a carrier of reducing equivalents. The rates of oxidation of the substrates of the l-glycerol 3-phosphate and the l-malate/1-aspartate substrate cycles were measured with the mitochondria isolated from the small intestinal mucosa. The key enzymes measured in the cytosol and mitochondria from the mucosa were NAD- l-glycerol 3-phosphate dehydrogenase, Fp- l-glycerol 3-phosphate dehydrogenase, l-malate dehydrogenase and l-glutamate-oxaloacetate transaminase. In addition, the substrate cycles were simulated in vitro by following NADH oxidation by isolated mitochondria in the presence of added cytosolic constituents.

Coaggregation with tumor cells inhibits expression by cerebellar cells of the adult isozyme locus, Gdc-1

Previous experiments suggested that there is an apparent requirement for a cell-contact mediated step in the control of the genes coding for the isozymes of l-glycerol 3-phosphate dehydrogenase, α-GPDH (EC 1.1.1.8). The basic features of this requirement have been investigated further by using reaggregating cultures of mixtures of cerebellar and telencephalon cells and three types of tumor cells, namely, C1300 neuroblastoma cells and the F9 and PCC4.aza/1 embryonal carcinoma cell lines. Enzyme expression in coaggregates between cerebellar and telencephalon cells indicates that each cell type functions independently in the coaggregate. That is, there is only a slight inhibition of the predicted α-GPDH activity and a slight increase of the predicted acetylcholinesterase activity. In contrast, coaggregation of cerebellar cells with X-irradiated tumor cells greatly reduces α-GPDH levels and suggests that the tumor cells are able to repress synthesis of adult-type isozyme in the cerebellar aggregates. Conditioned medium from neuroblastoma cultures did not block accumulation of α-GPDH. Based upon the relative amount of glucose phosphate isomerase allozymes in coaggregates, one neuroblastoma cell for every 10 cerebellar cells causes a 96% reduction in α-GPDH levels. The data are consistent with the hypothesis that components on the cell surface of tumor cells can alter the in vitro development of neonatal cerebellar cells.

A method for the isolation of triose phosphate isomerase, l-Glycerol 3-phosphate dehydrogenase, d-Fructose 1,6-bisphosphate aldolase and cytochrome [formula omitted] from a single extract of Ceratitis capitata flies

The isolation of homogeneous preparations of four proteins in high yields from a single extract of the Mediterranean fruit fly Ceratitis capitata is described. The four proteins are: triose phosphate isomerase (EC 5.3.1.1), l-glycerol 3-phosphate dehydrogenase (EC 1.1.1.8), d-fructose 1,6-bisphosphate aldolase (EC 4.1.2.13) and cytochrome c. l-Glycerol 3-phosphate dehydrogenase is obtained in preparative amounts in homogeneous form with a specific activity similar to that previously described. Triose phosphate isomerase and d-fructose 1,6-bisphosphate aldolase from C. capitata obtained in this way show amino acid composition comparable to those known for the enzymes from other sources.

Increased synthesis of l-glycerol 3-phosphate dehydrogenase during in vitro differentiation of reaggregating cerebellar cells

Reaggregating cell cultures of neonatal mouse cerebellar cells express many of the differentiated properties of normal developing cerebellum, including the transition for the embryonic and adult isozymes of l-glycerol 3-phosphate dehydrogenase (EC 1.1.1.8). In order to determine the mechanism leading to increased levels of adult isozyme, aggregates in culture from 2 to 17 days were labeled with radioactive leucine and the relative rate of enzyme synthesis was measured after purification of the enzyme by affinity chromatography on Blue Sepharose 6B. During the course of in vitro differentiation, the relative rate of synthesis increased 100-fold, such that it represented 0.5% of the total protein synthesized in the cytoplasmic fraction of the cell. In vivo, BALB cBy mice have twice the level of enzyme activity in the cerebellum as do C57BL 6J mice. Reaggregating cell cultures of cerebellar cells from these strains of mice also express a difference in the activity level, but only when the cerebellar cells are taken from mice 4 days of age or less. When the relative rates of synthesis of l-glycerol 3-phosphate dehydrogenase were measured in cultures expressing the strain-dependent difference in activity, these rates were found to be approximately twofold greater in cultures of BALB cBy cells. In contrast, estimates of the relative rate of enzyme degradation by the double-isotope labeling technique indicate that neither specific enzyme degradation nor degradation of total protein is different in aggregates from the two strains of mice. The results suggest that the genetic mechanisms controlling the levels of l-glycerol 3-phosphate dehydrogenase in the cerebellum during development are intrinsic to the cells and, with the exception of serum factors, are independent of systemic influences.

Comparison of activities of several enzymes and protein constituents of oviducal and breast muscle of Japanese quail, Coturnix coturnix Japonica

1. 1. Activities of several enzymes and protein constituents of magnum, isthmus, shell gland and breast muscle (pectoralis major) of Japanese quail, Coturnix coturnix japonica were compared. 2. 2. The respective activity per g wet weight of lactate dehydrogenase, malate dehydrogenase and l-glycerol 3-phosphate dehydrogenase in pectoralis major was approx 20 times that of these enzymes in isthmus which showed the highest activity among oviducal tissues. On the other hand, the respective activity of lactate dehydrogenase was similar to that of malate dehydrogenase and was approx 10–20 times that of l-glycerol 3-phosphate dehydrogenase in each tissue. 3. 3. Among NADPH-producing enzymes, NADP +-isocitrate dehydrogenase showed the highest activity in all tissues. The activity of malic enzyme was lowest in oviducal tissues, but was next to NADP +-isocitrate dehydrogenase in pectoralis major. 4. 4. Sodium dodecyl sulfate polyacrylamide gel electrophoretic patterns of the whole homogenate, the supernatant and the precipitate fraction of magnum, isthmus, shell gland and pectoralis major showed tissue specific protein compositions. Proteins with molecular weight of 55,000, 70,000, 110,000 and 130,000 were observed in the respective precipitate (myofibrilar) fraction of magnum, isthmus and shell gland, but not in that of pectoralis major. It was noteworthy that the amount of myosin heavy chain of magnum was markedly less than that of other three tissues.

Effect of Dietary DL-Ethionine on Egg Laying and Activities of Cytoplasmic and Mitochondrial L-glycerol 3-Phosphate Dehydrogenases in Liver and Kidney of Japanese Quail, Coturnix coturnix japonica

The effect of dietary DL-ethionine on egg laying and activities of succinate dehydrogenases, cytoplasmic and mitochondrial L-glycerol 3-phosphate dehydrogenases, in liver and kidney of Japanese quail, Coturnix coturnix japonica was investigated. When quail at full laying were fed a diet supplemented with DL-ethionine at 0.05%, 0.10%, 0.15% and 0.30% (w/w), respectively, apparent DL-ethionine concentration dependent inhibitions of egg laying rate, weights of ovary and oviduct, and egg weight were observed. At the 0.30% level, activity per g tissue of cytoplasmic L-glygerol 3-phosphate dehydrogenase from liver and kidney decreased to about one-half of the initial activity. A significant difference in the activity of mitochondrial L-glycerol 3-phosphate and succinate dehydrogenase from liver and kidney was obtained between the control and the DL-ethionine fed quail, respectively. These results indicated that dietary DL-ethionine inhibits egg laying and activities of L-glycerol 3-phosphate dehydrogenases and succinate dehydrogenase of both liver and kidney of Japanese quail.

Effect of Dietary DL-Ethionine and/or DL-Methionine on Egg Laying and Activities of Some Cytoplasmic NAD Linked-Dehydrogenases and NADPH-Producing Enzymes in Liver of Japanese Quail, Coturnix coturnix japonica

The effect of dietary DL-ethionine and/or DL-methionine on egg laying, and activities of some NAD linked-dehydrogenases and NADPH-producing enzymes in liver of Japanese quail, Coturnix coturnix japonica was investigated. A 0.30% DL-ethionine plus 0.30% DL-methionine supplemented diet reversed partially the egg laying inhibited by the diet with 0.30% DL-ethionine alone. No inhibitory effect on egg laying was observed for the diet supplemented with 0.30% DL-methionine alone. In marked contrast to the decreased activity of L-glycerol 3-phosphate dehydrogenase and malate dehydrogenase, significantly increased activity of lactate dehydrogenase was obtained for quail fed the DL-ethionine, and the DL-ethionine plus the DL-methionine supplemented diet, respectively. No marked changes in activities of these three dehydrogenases were obtained for quail fed the diet supplemented with DL-methionine alone. Although decreased activity was observed for all of the four NADPH-producing enzymes in quail fed the diet supplemented with DL-ethionine alone, the DL-ethionine plus DL-methionine, the smallest decrease was obtained for NADP-isocitrate dehydrogenase. The diet supplemented with DL-methionine alone induced markedly the respective activity of malic enzyme and glucose 6-phosphate dehydrogenase. These results indicate a relatively important function of NADP-isocitrate dehydrogenase for NADPH-production even under DL-ethionine toxicity and suggest complicated relationships between egg production and activities of enzymes associated with carbohydrate and lipid metabolism in quail liver.

Differential hormonal regulation of l-glycerol 3-phosphate dehydrogenase in rat brain and skeletal muscle

The level of l-glycerol 3-phosphate dehydrogenase (EC 1.1.1.8) is regulated in the rat brain by glucocorticoids. Following hypophysectomy, the concentration of brain glycerol-3-P dehydrogenase decreases to about 40% of the control. By immunotitration, we have demonstrated that this decrease in glycerol-3-P dehydrogenase activity is due to fewer enzyme molecules rather than less efficient ones. We also demonstrated that the enzyme remaining in the brain after hypophysectomy is identical to that found in the brains of control littermates, as determined by gel permeation chromatography, pH optimum, heat lability, electrophoretic mobility, and Ouchterlony double-diffusion analysis. Since the concentration of glycerol-3-P dehydrogenase in skeletal muscle is not regulated by glucocorticoids, we also compared the brain enzyme to the muscle enzyme. By the above criteria, skeletal muscle glycerol phosphate dehydrogenase is identical to the brain enzyme. This suggests that the same structural gene codes for glycerol-3-P dehydrogenase in brain and muscle and that the difference in response to glucocorticoids is due to the presence of a specific regulatory mechanism in brain that is absent in muscle.

The transition from embryonic to adult isozyme expression in reaggregating cell cultures of mouse brain

The transition from embryonic to adult l-glycerol 3-phosphate dehydrogenase (EC 1.1.1.8) was examined in reaggregating cell cultures of mouse brain. Culture conditions were selected that enabled viable aggregates to be produced from neural cells of mice that ranged in age from the 12th day of gestation to 6 days of postnatal age. In all cultures, an increase in the specific and total activity of l-glycerol 3-phosphate dehydrogenase was observed and this was due to an increase in the adult isozyme. The cultures from the older cells, i.e., cerebellar aggregates from mice 6 days of age, expressed approximately a 50-fold increase in activity, whereas cerebellar aggregates from newborn mice exhibited about a three-fold increase in activity. In both cases, the time course for the developmental increase followed the normal temporal sequence. The amount of l-glycerol 3-phosphate dehydrogenase activity in a cerebellar aggregate from a 6-day-old mouse was greater than 1% of the soluble cellular protein, which is about seven times higher than the specific activity determined in the cerebellums of adult mice. Alleles at the structural locus for l-glycerol 3-phosphate dehydrogenase, the Gdc-1 locus, and those alleles that control the activity levels in the cerebellums of mice were expressed in aggregates from BALB cBy and C57BL 6J neonates. However, although the expected structural allele was expressed in all cultures, the expression of activity differences in cerebellar aggregates depended on the age of the mouse from which the cerebellar cells were isolated. Acetylcholinesterase (EC 3.1.1.7) was also measured in these aggregates; the specific activities were highest in aggregates from mice in the 16th day of gestation and least in the cerebellar aggregates of neonates, a trend that was opposite to that of l-glycerol 3-phosphate dehydrogenase.

Effect of dietary DL-ethionine on postnatal growth, and activities of liver and kidney enzymes of male chickens, gallus domesticus

1. 1. Effect of dietary DL-ethionine on postnatal growth, and activities of liver and kidney enzymes of male chickens were investigated up to 8 days of age. 2. 2. The 0.20% dietary DL-ethionine depressed the weight gain and respective growth of liver, kidney and adrenal, but induced an accumulation of hepatic total lipid and significantly lower rectal temperature after 4 days of age. 3. 3. Respective activity of mitochondrial L-glycerol 3-phosphate dehydrogenase, succinate dehydrogenase and choline dehydrogenase from liver and kidney of the DL-ethionine fedchickens were significantly lower than those of the normal chicken. 4. 4. Activity per gram kidney of cytoplasmic L-glycerol 3-phosphate dehydrogenase was significantly higher than that per gram liver for both the normal and the DL-ethionine fed chicken. The enzyme activity was higher for the DL-ethionine fed chicken than the normal, whereas the activity of this enzyme from liver of the DL-ethionine fed chicken at 8 days of age became lower than that of the normal. 5. 5. Relationships between activities of these liver and kidney enzymes and lower rectal temperature were discussed from the viewpoint of energy metabolism.

Photoperiod dependent activities of cytoplasmic l-glycerol 3-phosphate dehydrogenase and other enzymes in liver and kidney of male japanese quail, Coturnix coturnix japonica

1. 1. Male Japanese quail, Coturnix coturnix japonica (35 days of age) were kept for 35–45 days under 16L:8D (16hr light:8hr dark) or 8L:16D (8 hr light:16hr dark). 2. 2. Weight of liver, and content of glycogen and lipid per g liver of quail (70–80 days of age) under 8L:16D were significantly higher than those under 16L:8D. 3. 3. The respective activity per mg protein or g liver of glucose 6-phosphate dehydrogenase, malic enzyme, lactate dehydrogenase, NADP-isocitrate dehydrogenase, succinate dehydrogenase and choline dehydrogenase in liver from quail under 8L:16D was significantly higher than under 16L:8D, while the activity of cytoplasmic l-glycerol 3-phosphate dehydrogenase was significantly higher under 16L:8D than under 8L:16D. 4. 4. Concerning kidney enzymes, no significant difference was obtained for most of the enzymes examined except succinate dehydrogenase, and choline dehydrogenase which were significantly higher under 8L:16D than under 16L:8D.

Hormonal induction of cytoplasmic l-glycerol 3-phosphate dehydrogenase and other enzymes in liver of Japanese quail under a short daily photoperiod

1. 1. Male Japanese quail were kept for at least 35 days from 35 to 70 days of age under a short daily photoperiod of 8L:16D and were injected with various hormones intraperitoneally in order to estimate the direction media of photostimulation under a longer daily photoperiod to hepatic enzymes. 2. 2. Marked respective inductive effect of triamcinolone, hydrocortisone and porcine adrenocorticotropic hormone on activity of cytoplasmic l-glycerol 3-phosphate dehydrogenase was obtained, whereas no such inductive effect was obtained for testosterone propionate, cyclic AMP, triiodothyronine and epinephrine. 3. 3. The maximum inductive effect of cytoplasmic l-glycerol 3-phosphate dehydrogenase was obtained at around 4–5 days after a single daily dose of triamcinolone of 0.2–2.0 nmoles. The increase of activity of this enzyme by triamcinolone was inhibited by simultaneous administration of cycloheximide.

Photoperiod dependent turnover of cytoplasmic l-glycerol 3-phosphate dehydrogenase and other enzymes in liver of male japanese quail, Coturnix coturnix japonica

1. 1. Turnover of cytoplasmic l-glycerol 3-phosphate dehydrogenase (G3PDH), lactate dehydrogenase (LDH) and malic enzyme (ME) in liver of male Japanese quail, Coturnix coturnix japonica, was estimated by a daily photoperiodic manipulation under a constant ambient temperature. 2. 2. When a daily photoperiod was decreased from 16L:8D (16hr light:8hr dark) to 8L:16D (8hr light: 16 hr dark), G3PDH decreased with half-life of 7.04 day, and LDH increased with half-life of 2.92 day. ME increased for the first 9 days with half-life of 1.85 day and thereafter, decreased with half-life of 1.88 day. 3. 3. When a daily photoperiod was increased from 8L:16D to 16L:8D, LDH and ME decreased with half-life of 5.07 and 2.83 day, respectively, and G3PDH increased with half-life of 3.40 day and thereafter decreased with half-life of 2.58 day, to the control level under a constant daily photoperiod of 16L:8D, not to that under 8L:16D. 4. 4. A marked difference in activity of ME under the increased daily photoperiod was obtained between the normal and the castrated quail, but no such difference was obtained for G3PDH. 5. 5. Actinomycin D and cycloheximide injected intraperitoneally to the castrated quail inhibited respectively, the increase of G3PDH under the increased daily photoperiod of 16L:8D.