File:The Biological bulletin (19753102314).jpg

Title: The Biological bulletin
Identifier: biologicalbullet122mari (find matches)
Year: [1] (s)
Authors: Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983
Subjects: Biology; Zoology; Biology; Marine Biology
Publisher: Woods Hole, Mass. : Marine Biological Laboratory
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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242 SYLVAN NASS 7. Inhibitors. Both the endogenous and exogenous activities of yolk fractions were markedly inhibited by ammonium molybdate, suggesting that both reactions were enzymatically similar. The Lineweaver-Burk plot of molybdenum inhibition of PPPase extracted from the pigment fraction showed this polyanion to be a non- competitive inhibitor of the enzyme. The ammonium molybdate was observed to precipitate a very small quantity of non-TCA-precipitable material when added to an incubation mixture. The clouding that was usually found when molybdate was added during the Fiske-Subbarow procedure was not observed when this reagent was added to molybdate-inhibited incubation mixtures after TCA precipitation. Inhibition was 50% at 10~4 M molybdenum. Other reagents that were reported to be activators and inhibitors of mammalian PPPase (Feinstein and Volk, 1949; Norberg, 1950; Sundararajan and Sarma, 1954; Paigen, 1958), including thioglycollic acid, desoxycholate, ascorbic acid, hydrogen peroxide, and phenanthroline, did not affect frog PPPase at concentrations of 10~2 M. Oxalate, iodoacetate, cyanide, and fluoride were equally ineffective. D. Changes in PPPase activity during development of frog embryos Figure 10 shows that the amount of YPB protein per embryo decreased sharply after stage 20 (hatching). Pigment residues, obtained from ovaries and embryos at different stages of development, were incubated individually with YPB of stage 2, stage 4, stage 10, stage 20, and with phosvitin. The activities of each residue
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15 30 45 60 75 MINUTES 105 120 FIGURE 5. Rate of phosphate hydrolysis and protein change from a water-precipitable to a water-soluble state by the action of pigment extract upon heated yolk platelets in 0.4 M XaCl, PH 4.9, 28° C.

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