Phosphorylation of myo-inositol in ripening grains of rice and wheat. Incorporationof phosphate-32P and myo-inositol-3H into myo-inositol phosphates

To elucidate the mechanism of the phosphorylation of myo-inositolin the process of phytate formation, feeding experiments oforthophosphate-³²P and myo-inositol-³H in the ripening grainsof rice and wheat were performed. It was found that ³²P and³H were incorporated into myo-inositol mono- and hexa-phosphates.The same results were obtained when a mixture of "cold" myo-inositolpolyphosphates was administered to the grains before feedingphosphate-³²P. Based on these results it is concluded that phosphorylationof free myo-myo-inositol in the formation of phytate does nottake place in a stepwise fashion but may proceed through anunknown myo-inositol derivative. (Received August 2, 1967; )     

FORMATION OF MYO-INOSITOL AND PHYTIN IN RIPENING RICE GRAINS

With the view to elucidate the role of myo-inositol in the ripeningprocess of rice grains, its distribution, formation and conversionwere studied.

1. myo-Inositol in the ripening rice grains was fractionated intofree-, phosphate ester- and phosphoinositide-forms. At the earlystage of ripening, a considerable part of myo-inositol was foundin free state, and at the end of ripening stage the most partwas found in phosphate ester-state, phytic acid. The contentof phosphoinositide in the grains was low during the ripeningperiod.
2. The occurrence of biosynthesis of myo-inositol inthe ripeningrice grains was confirmed by the observation ofincorporationof ¹⁴C into myo-inositol from ¹⁴C-sugars and itwas found, fromthe feeding experiment of myo-inositol- thatmyo-inositol doesnot undergo reactions further than phosphorylation.
3. The feeding experiment of glucose-l-³²P showed that the distributionpattern of ³²P in different fractions of grain material wasthe same as that of ³²P-phosphate, indicating that phytic acidis one of the final products of phosphorus metabolism in theripening rice grains.
4. These results led to the assumptionthat myo-inositol mightact as an acceptor of phosphorus toremove inorganic phosphorusin favor of starch synthesis byphosphorylase.

(Received September 12, 1962; )     

The growth promoting effect of phytic acid on callus tissues of rice seed

The effects of phytic acid, myo-inositol hexaphosphoric acid,in the induction and growth of rice seed callus were studied.Phytic acid was substituted for myo-inositol in the inductionof the callus and preferable effects were shown on the growthof the callus. ¹Present address: Hyogo Agricultural Experiment Station, Akashi,Hyogo, Japan (Received June 30, 1970; )     

PHOTOSYNTHESIS OF GLYCINE AND SERINE IN GREEN PLANTS

1. The effects of "carbonyl" reagents on the photosyntheticin-corporation of ¹⁴CO₂ into the assimilation products of tobaccoand spinach leaves were studied. The presence of "carbonyl"reagents causes an increase in the ratio of ¹⁴CO₂ incorporatedin glycine and a decrease in serine. The incorporation of ¹⁴Cfrom glycolate-1-¹⁴C and glycolaldehyde-2-¹⁴C into glycine andserine was also affected by "carbonyl" reagents, as in the caseof ¹⁴CO₂-experiment. 2. The feeding experiments of glycine-1-¹⁴C and serine-1-¹⁴Cin the presence and in the absence of "carbonyl" reagents revealedthat these reagents inhibit the conversion of glycine to serine. 3. The results obtained above, together with the effects ofthiols on ¹⁴CO₂ incorporation presented in this paper, supportthe assumption that glycine and serine are formed via glycolateand glyoxylate during photosynthesis in green plants. 4. Comparison of ¹⁴C incorporation in malate from ¹⁴CO₂, glycolate-1-¹⁴C,glycine-1-¹⁴C and serine-1-¹⁴C in the presence and in the absenceof "carbonyl" reagents suggested the occurrence of the pathwayof the malate formation via glycolate and glyoxylate, not passingthrough glycine and serine, during photosynthesis. ¹ A part of this paper was presented at the Symposium on "Nitrogenand Plant" by the Japanese Society of Plant Physiologists, inOctober, 1963 ² Present address: Radiation Center of Osaka Prefecture, Sakai,Osaka     

EFFECT OF {alpha}-HYDROXYSULFONATES ON PHOTOCHEMICAL REACTIONS OF SPINACH CHLOROPLASTS AND PARTICIPATION OF GLYOXYLATE IN PHOTOPHOSPHORYLATION

1. The effect of -hydroxy sulfonates and sulfite, inhibitors ofglycolate oxidase, on the photochemical reactions of spinachchloroplasts was studied. The photo reduction of ferricyanideand NADP was not affected by the poisons, whereas the photophosphorylationand ¹⁴CO₂ fixation were inhibited.
2. Glyoxylate was photoreducedby the chloroplasts in the presenceof PPNR and glyoxylate reductase,and this reduction was acceleratedby the addition of NADP.ATP formation accompanied with thereduction of glyoxylate bythe illuminated chloroplasts wasobserved. It is supposed thatglyoxylate oxidizes the photoreducedNADPH₂ or PPNR and thusthe photophosphorylation is stimulated.

¹A part of this paper was presented at the annual meeting ofAgricultural Society of Japan, in August, 1964. ²Present address: Radiation Center of Osaka Prefecture, Sakai,Osaka.     

INHIBITION OF THE PHOTOSYNTHETIC CARBON DIOXIDE FIXATION OF GREEN PLANTS BY {alpha}-HYDROXYSULFONATES, AND ITS EFFECTS ON THE ASSIMILATION PRODUCTS

1. Several kinds of a-hydroxysulfonates, the bisulfite additioncompounds of aldehydes and ketones, were found to inhibit thephotosynthetic carbon dioxide fixation of the barley and wheatseedlings, tobacco leaf and Chlorella cells. Bisulfite additioncompounds of glyoxal, glyoxylate and benzaldehyde were moreeffective in this respect than those of formaldehyde and acetaldehyde.
2. The presence of -hydroxysulfonate causes an increase in ratiosof :¹⁴CO₂ incorporated in glycolate and alanine, and a decreasein incorporation in serine, malate, isocitrate and citrate.It was inferred that these changes are caused by the blockingof the formation of glyoxylate through inhibition of glycolicacid oxidase by the poison.
3. A reaction scheme was proposedto account for the above-statedresults, and the bearing ofthese findings on the possible roleof glycolic acid oxidasein the photosynthetic carbon dioxidefixation and in the formationof amino and organic acids wasdiscussed.

(Received December 8, 1961; )     

Conservation of electron transport and energy transfer reactions of spinach chloroplasts in glycero

When spinach chloroplasts were suspended in 50% glycerol inthe presence of 5 mM sodium chloride, then stored at –20°Cactivity of the Hill reaction was retained for several monthswith a small loss. Under these conditions photophosphorylationactivity was reduced by half during the month of storage. (Received February 2, 1971; )     

Purification and properties of cytochrome c and two peroxidases from spinach leaves

1. A simultaneous purification procedure of cytochrome c, peroxidases,ferredoxin, ferredoxin-NADP reductase and sulfite reductasefrom spinach leaves is described. Cytochrome c, ferredoxin andferredoxin-NADP reductase were prepared in crystalline states.The two peroxidases were obtained in homogeneous states as evidencedby their electrophoretic patterns on acrylamide gel and sedimentationanalysis. 2. Crystalline cytochrome c showed a molecular weight of 13,800and an E₀' of 270 mv at pH 7.0. In addition to these properties,its spectral pattern also indicated that this cytochrome c wasderived from mitochondria. 3. Two peroxidases were isolated in high spin forms after treatmentwith HgCl₂. They had a-peaks at 556 mµ in their reducedforms. Although both peroxidases showed small differences inchromatographic behavior on a carboxymethyl cellulose column,' they had similar spectral properties, dissociation constantsof peroxidase-cyanide complex and rate constants for peroxidasereactions. (Received December 24, 1970; )