scholarly journals The Inhibition of Photosynthesis by Oxygen II. The Effect of Oxygen on Glyceraldehyde Phosphate Dehydrogenase From Chloroplasts

1958 ◽  
Vol 11 (3) ◽  
pp. 336 ◽  
Author(s):  
JS Turner ◽  
JF Turner ◽  
KD Shortman ◽  
Judith E King
Keyword(s):  
Enzyme Activity ◽  
Glyceraldehyde Phosphate Dehydrogenase ◽  
Effect Of Oxygen ◽  
Silver Beet

(i) An extract containing glyceraldehyde phosphate dehydrogenases was prepared from the chloroplasts of silver beet. Diphosphopyridine nucleotide (DPN) and triphosphopyridine nucleotide (TPN) functioned as cofactorS for the enzyme activity.

A Labile CO2-Fixing Enzyme Complex in Spinach Chloroplasts

1972 ◽  
Vol 27 (8) ◽  
pp. 925-932 ◽  
Author(s):  
Bruno Müller
Keyword(s):  
Molecular Weight ◽  
Enzyme Activity ◽  
Phosphoglycerate Kinase ◽  
Gel Chromatography ◽  
Enzyme Complex ◽  
Molecular Weights ◽  
Spinach Chloroplasts ◽  
Reversible Dissociation ◽  
Glyceraldehyde Phosphate Dehydrogenase ◽  
Ribulose Diphosphate Carboxylase

Activity and activation of ribulose 5-phosphate kinase, ribulose diphosphate carboxylase, phosphoglycerate kinase, and the NADP- and NAD-dependent glyceraldehyde phosphate dehydrogenases from isolated diloroplasts were traced in the course of differential ultracentrifugation. Activation of some of these enzymes was carried out by incubation with NADPH2 or ATP. Activity of ribulose diphosphate carboxylase could be increased 2,4-fold by incubation with NADPH2 while phosphoglycerate kinase could not be activated.The degree of activation of the NADP-specific glyceraldehyde phosphate dehydrogenase and ribulose phosphate kinase was correlated with the velocity of sedimentation. Enzymes, which could be activated manifold, sedimented more quickly. Two fractions could be obtained after ultracentri fugation: the sedimented fraction could be highly activated while the fraction in the supernatant could not.It was shown by gel chromatography with Sephadex for the NADP-specific glyceraldehyde phosphate dehydrogenase and ribulose phosphate kinase that the enzyme fractions which could be greatly activated had molecular weights of at least 400 000. In contrast, the enzyme fraction which could not be activated had a molecular weight of 50 000 for the ribulose phosphate kinase and of 240 000 for the glyceraldehyde phosphate dehydrogenases.Results are discussed in the way that a reversible dissociation of a labile enzyme complex takes place between ribulose phosphate kinase, glyceraldehyde phosphate dehydrogenases, and ribulose diphosphate carboxylase. Enzyme activity changes with the state of aggregation. The dissociated enzymes have higher activity than the complexed ones. Dissociation can be performed by ATP and NADPH2, which are assumed to be the physiological regulators, and by unphysiological means as dilution and high salt concentrations.

Morphological and biochemical analyses of changes in rat hepatocytes related to wine and ethanol consumption

1984 ◽  
Vol 42 ◽  
pp. 232-233
Author(s):  
S.M. Geyer ◽  
C.L. Mendenhall ◽  
J.T. Hung ◽  
E.L. Cardell ◽  
R.L. Drake ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Enzyme Activity ◽  
Malic Enzyme ◽  
Smooth Endoplasmic Reticulum ◽  
Rat Hepatocytes ◽  
Mature Male ◽  
Treatment Groups ◽  
Malic Enzyme Activity ◽  
Biochemical Analyses

Thirty-three mature male Holtzman rats were randomly placed in 3 treatment groups: Controls (C); Ethanolics (E); and Wine drinkers (W). The animals were fed synthetic diets (Lieber type) with ethanol or wine substituted isocalorically for carbohydrates in the diet of E and W groups, respectively. W received a volume of wine which provided the same gram quantity of alcohol consumed by E. The animals were sacrificed by decapitation after 6 weeks and the livers processed for quantitative triglycerides (T3), proteins, malic enzyme activity (MEA), light microscopy (LM) and electron microscopy (EM). Morphometric analysis of randomly selected LM and EM micrographs was performed to determine organellar changes in centrilobular (CV) and periportal (PV) regions of the liver. This analysis (Table 1) showed that hepatocytes from E were larger than those in C and W groups. Smooth endoplasmic reticulum decreased in E and increased in W compared to C values.

A TEM study of the effect of oxygen on nanocavity formation and precipitation in rapid - solidified Fe-16Ni-9Cr stainless steels

1994 ◽  
Vol 52 ◽  
pp. 700-701
Author(s):  
S. Wisutmethangoon ◽  
T. F. Kelly ◽  
J.E. Flinn
Keyword(s):  
Stainless Steels ◽  
High Mobility ◽  
Hot Extrusion ◽  
Extrusion Ratio ◽  
Gas Atomization ◽  
Cavity Formation ◽  
Nucleation Sites ◽  
Heat Treated ◽  
Different Types ◽  
Effect Of Oxygen

Vacancies are introduced into the crystal phase during quenching of rapid solidified materials. Cavity formation occurs because of the coalescence of the vacancies into a cluster. However, because of the high mobility of vacancies at high temperature, most of them will diffuse back into the liquid phase, and some will be lost to defects such as dislocations. Oxygen is known to stabilize cavities by decreasing the surface energy through a chemisorption process. These stabilized cavities, furthermore, act as effective nucleation sites for precipitates to form during aging. Four different types of powders with different oxygen contents were prepared by gas atomization processing. The atomized powders were then consolidated by hot extrusion at 900 °C with an extrusion ratio 10,5:1. After consolidation, specimens were heat treated at 1000 °C for 1 hr followed by water quenching. Finally, the specimens were aged at 600 °C for about 800 hrs. TEM samples were prepared from the gripends of tensile specimens of both unaged and aged alloys.

Reductive light activation of enzyme activity

2000 ◽  
Vol 110 (3) ◽  
pp. 295-295
Author(s):  
Louise Anderson ◽  
Per Gardestrom
Keyword(s):  
Enzyme Activity ◽  
Light Activation
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