Ergönül P.G., Nergiz C. (2010): Determination of organic acids in olive fruit by HPLC. Czech J. Food Sci., 28: 202–205. Organic acids (oxalic, citric, malic, and succinic) contents of Domat, Memecik and Uslu varieties of olives grown in Turkey were investigated using HPLC method. Organic acids were extracted from olives with water-methanol mixture solution 75:25 (v/v) and were analysed through ...

NAD malic enzyme can exist in dimer, tetramer, or octamer form. Freshly prepared enzyme from Solanum tuberosum var. Chieftan exists predominantly as the octamer and during storage is progressively converted into lower molecular weight forms. High ionic strength favors dimer formation, whereas high concentrations of malate or citrate favor tetramer formation. The tetramer is the most active form...

Cells from photoautotrophic cultures o f Chenopodium rubrum were fractionated for the iso­ lation o f purified chloroplasts and mitochondria. The subcellular localization o f the enzymatic activities involved in the metabolism o f malic acid was investigated. Highly purified chloro­ plasts were obtained from the protoplasts, whereas peroxisomes were still present in the mito­ chondrial fraction...

The TPN+-specitk malic enzyme from Escherichia coli has been purified from malate-grown cells. An approximately loo-fold purified preparation is activated by NH4+ and K+ ions. The enzyme is inhibited by acetyl coenzyme A, oxalacetate, TPNH, and DPNH in an allosteric manner. Glycine at concentration ranges above 0.5 M has been shown to activate the enzyme as well as to desensitize it reversibly ...

Pyruvate carboxylation in the isolated perfused rat heart was studied under steady-state conditions. A biotin deficiency resulting in a 90% decrease in myocardial pyruvate carboxylase left the pyruvate carboxylation rate unchanged. Pyruvate carboxylation in heart muscle must therefore take place by means of an enzyme which does not contain biotin. The kinetic properties and mass-action ratio of...

Fern spermatozoids respond chemotactically to concentration gradients of malic or maleic acid salts (Pfeffer, 1884). They respond weakly to salts of a few other dicarboxylic acids, but do not respond to succinate or fumarate (Shibata, 1911; Rothschild, 1956). Previous workers concluded, without adequate justification, that the malate ion, and not the undissociated malic acid molecule, is chemot...

The title compound, C(10)H(14)O(5), is an inter-mediate in our study of the asymmetric synthesis of α-hydroxy-alkanoic acids. The structure consists of 1,4-dioxaspiro[4,5]decane skeleton formed when the cyclohexylidene group binds to both of the hydroxyl groups of carboxylic groups of the starting malic acid. The six-membered ring adopts a chair conformation.