Woronick and Johnson (1) observed in Aspergillus niger extracts a pyruvate carboxylating system requiring adenosine triphosphate, but not involving phosphopyruvate, and suggested that the carboxylation reaction was coupled with the conversion of adenosine triphosphate to adenosine diphosphate and inorganic phosphate. Utter and Keech (2) studied a similar reaction in extracts of avian and beef l...

1. A simple kinetic method was devised to show whether dissolved CO2 orHCO3ion is the substrate in enzyme-catalysed carboxylation reactions. 2. The timecourse of the reductive carboxylation of 2-oxoglutarate by NADPH, catalysed by isocitrate dehydrogenase, was studied by a sensitive fluorimetric method at pH 7-3 and pH 6-4, with large concentrations of substrate and coenzyme and small carbon di...

The present work is concerned with an enzyme, obtained from an acetone powder of spinach leaves, which catalyzes the carboxylation of phosphorylenolpyruvate’ to yield, under the conditions of isolation here employed, oxalacetate and inorganic phosphate. Pyruvate or pyruvate plus ATP will not substitute for PEP. Reduced triphosphopyridine nucleotide is not added to the reaction mixture and malat...

The posttranslational gamma-carboxylation of glutamate residues in secreted proteins to gamma-carboxyglutamate is carried out by the vitamin K-dependent enzyme gamma-glutamyl carboxylase. gamma-Carboxylation has long been thought to be a biochemical specialization of vertebrates, essential for blood clotting. Recently, a gamma-carboxylase was shown to be expressed in Drosophila, although its fu...

Photosynthesis, Dark Fixation, /?-Carboxylation, C4-Metabolism, Brown Algae Marine brown macroalgae including Macrocystis integrifolia, Nereocystis luetkeana, Lessoniopsis littoralis, Laminaria saccharina, Fucus serratus and some further representatives of the Laminariales and Fucales (Phaeophyta) have been investigated with respect to their remarkably high potential for /?-carboxylation of pho...

The 0-24-h urinary metabolic profile of cyclophosphamide was inves tigated in a series of 14 patients with various malignancies receiving combination chemotherapy including i.v. cyclophosphamide. This was accomplished using combined thin-layer chromatography-photographydensitometry, which can quantitate cyclophosphamide and its four prin cipal urinary metabolites (4-ketocyclophosphamide, nor-ni...

Acclimation of photosynthesis to elevated CO2 has previously been shown to be more pronounced when N supply is poor. Is this a direct effect of N or an indirect effect of N by limiting the development of sinks for photoassimilate? This question was tested by growing a perennial ryegrass (Lolium perenne) in the field under elevated (60 Pa) and current (36 Pa) partial pressures of CO2 (pCO2) at l...