Biochemical Reagents

Bergmeyer, Hans‐Ulrich; Klotzsch, Helmut; Möllering, Hans; Nelböck-Hochstetter, Michael; Beaucamp, Klaus

doi:10.1016/b978-0-12-395630-9.50166-3

Cited by 86 publications

(107 citation statements)

References 85 publications

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“…Pyruvate kinase (EC 2.7.1.40) was assayed as described by Bergmeyer et al (1), and the assay was started with 5 mM ADP. Pyruvate P i dikinase (EC 2.7.9.1) and pyruvate water dikinase (EC 2.7.9.2) were assayed by using the same method, but starting with 5 mM AMP plus 20 mM Na 4 PP i and 5 mM AMP plus 20 mM KH 2 PO 4 , respectively.…”

Section: Methodsmentioning

confidence: 99%

Catabolic and anabolic enzyme activities and energetics of acetone metabolism of the sulfate-reducing bacterium Desulfococcus biacutus

Janssen

Schnik

1995

J Bacteriol

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Acetone degradation by cell suspensions of Desulfococcus biacutus was CO 2 dependent, indicating initiation by a carboxylation reaction, while degradation of 3-hydroxybutyrate was not CO 2 dependent. Growth on 3-hydroxybutyrate resulted in acetate accumulation in the medium at a ratio of 1 mol of acetate per mol of substrate degraded. In acetone-grown cultures no coenzyme A (CoA) transferase or CoA ligase appeared to be involved in acetone metabolism, and no acetate accumulated in the medium, suggesting that the carboxylation of acetone and activation to acetoacetyl-CoA may occur without the formation of a free intermediate. Catabolism of 3-hydroxybutyrate occurred after activation by CoA transfer from acetyl-CoA, followed by oxidation to acetoacetyl-CoA. In both acetone-grown cells and 3-hydroxybutyrate-grown cells, acetoacetyl-CoA was thiolytically cleaved to two acetyl-CoA residues and further metabolized through the carbon monoxide dehydrogenase pathway. Comparison of the growth yields on acetone and 3-hydroxybutyrate suggested an additional energy requirement in the catabolism of acetone. This is postulated to be the carboxylation reaction (⌬G؇ for the carboxylation of acetone to acetoacetate, ؉17.1 kJ ⅐ mol ؊1). At the intracellular acyl-CoA concentrations measured, the net free energy change of acetone carboxylation and catabolism to two acetyl-CoA residues would be close to 0 kJ ⅐ mol of acetone ؊1, if one mol of ATP was invested. In the absence of an energy-utilizing step in this catabolic pathway, the predicted intracellular acetoacetyl-CoA concentration would be 10 13 times lower than that measured. Thus, acetone catabolism to two acetyl-CoA residues must be accompanied by the utilization of the energetic equivalent of (at least) one ATP molecule. Measurement of enzyme activities suggested that assimilation of acetyl-CoA occurred through a modified citric acid cycle in which isocitrate was cleaved to succinate and glyoxylate. Malate synthase, condensing glyoxylate and acetyl-CoA, acted as an anaplerotic enzyme. Carboxylation of pyruvate or phosphoenolpyruvate could not be detected.The anaerobic metabolism of acetone appears to involve an initial carboxylation of acetone to acetoacetate (or acetoacetyl coenzyme A [acetoacetyl-CoA]), followed by thiolytic cleavage to two acetyl-CoA residues (3, 32-35). The carboxylation reaction has not been measured in vitro, and evidence has come from 14 C labelling studies (32,33,35). Carboxylation reactions appear to play a role in a number of anaerobic transformations (16, 44), but these reactions have not been well studied. The carboxylation of acetone to acetoacetate, CH 3 COCH 3 ϩ HCO 3), is an endergonic reaction (42). Thus, the energetic equivalent of about 1/3 mol of ATP (⌬GЊЈ of ATP hydrolysis, Ϫ50 kJ ⅐ mol Ϫ1 [42]) is required, but the mechanism of coupling is not known. In addition, attempts to measure the carboxylase in sulfate-reducing bacteria have remained unsuccessful (21).Many genera of sulfate-reducing bacteria are able to oxidize completely (to CO ...

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Section: Methodsmentioning

confidence: 99%

Catabolic and anabolic enzyme activities and energetics of acetone metabolism of the sulfate-reducing bacterium Desulfococcus biacutus

Janssen

Schnik

1995

J Bacteriol

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“…Guaiacol peroxidase was measured by the method of Bergmeyer et al (1974) with a reaction mixture consisting of 50 mM of sodium phosphate buffer (pH 7.0), 2 mM of H 2 O 2 , and 20 mM of guaiacol. The reaction was initiated with the addition of 100 mL of enzyme extract.…”

mentioning

confidence: 99%

Biophysical probing of Spartina maritima photo-system II changes during prolonged tidal submersion periods

Duarte

Santos

Marques

2014

Plant Physiology and Biochemistry

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a b s t r a c tSubmergence is one of the major constrains affecting wetland plants, with inevitable impacts on their physiology and productivity. Global warming as a driving force of sea level rise, tend to increase the submersion periods duration. Photosynthesis biophysical probing arise as an important tool to understand the energetics underlying plant feedback to these constrains. As in previous studies with Spartina maritima, there was no inhibition of photosynthetic activity in submerged individuals. Comparing both donor and acceptor sides of the PSII, the first was more severely affected during submersion, driven by the inactivation of the OEC with consequent impairment of the ETC. Although this apparent damage in the PSII donor side, the electron transport per active reaction centre was not substantially affected, indicating that this reduction in the electron flow is accompanied by a proportional increase in the number of active reaction centres. These conditions lead to the accumulation of excessive reducing power, source of damaging ROS, counteracted by efficient energy dissipation processes and anti-oxidant enzymatic defences. This way, S. maritima appears as a well-adapted species with an evident photochemical plasticity towards submersion, allowing it to maintain its photosynthetic activity even during prolonged submersion periods.

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“…Enzymes assayed were phosphofructokinase (EC 2.7.1.11) (Dennis and Coultate, 1967), hexokinase (EC 2.7.1.1.) (Tsai, Salamini and Nelson, 1970), pyruvate kinase (EC 2.7.1.40) (Hess and Wieker, 1974), fructose-1, 6-biphosphate aldolase (EC 4.1.2.13) (Rutter et al^ 1966), glucose-6-phosphate dehydrogenase (EC 1.1.1.49) (Glock and McLean, 1953), phosphoglycerate kinase (EC 2.7.2.3) (Bergmeyer, Gawehn and Grassl, 1974), 6-phosphogluconate dehydrogenase (EC 1.1.1.44) (Glock and McLean, 1953), transketolase (EC 2.2.2.1.1) (De la Haba and Racker, 1955) and transaldolase (EC 2.2.1.2) (Venkataraman and Racker, 1961). With pyruvate kinase, hexokinase, phosphoglycerate kinase and phosphofructokinase, the buffer used was 0.05 M HEPES (N-2-hydroxyethyl piperazine-N-ethane sulphonic acid), pH 7.5.…”

Section: Methodsmentioning

confidence: 99%

Carbohydrate Oxidation in Developing Barley Endosperm

Duffus

Rosie

1977

New Phytologist

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SUMMARYThe presence of a number of pentose phosphate pathway (PPP) enzymes in developing barley endosperm is reported. The relative importance of the Embden-Meyerhof-Parnas pathway (EMPP) and the PPP throughout endosperm development was assessed by following the changes in activity of five EMPP and four PPP enzymes. The patterns of activity of the EMPP enzymes were very similar with pronounced peaks of activity at 35 days after anthesis thereafter falling to low or zero levels at the onset of maturity. The PPP enzymes, on the other hand, rose to maximum levels around 30-35 days falling only slightly thereafter.

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Biochemical Reagents

Cited by 86 publications

References 85 publications

Catabolic and anabolic enzyme activities and energetics of acetone metabolism of the sulfate-reducing bacterium Desulfococcus biacutus

Catabolic and anabolic enzyme activities and energetics of acetone metabolism of the sulfate-reducing bacterium Desulfococcus biacutus

Biophysical probing of Spartina maritima photo-system II changes during prolonged tidal submersion periods

Carbohydrate Oxidation in Developing Barley Endosperm

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