Rapid derivatization and gas chromatographic determination of amino acids

Chromatographic methods are increasingly being used for the quantitative determination of endogenous compounds in biological samples. This article presents an overview of the specific issues, which have to be taken into account for the development, validation and application of these methods. The usual lack of analyte-free samples of the biological matrix implies that alternative strategies for calibration have to be followed. This article compares and discusses the advantages and disadvantages of two strategies – the use of the authentic analyte in a surrogate matrix and the use of a surrogate analyte in the authentic matrix. In addition, it highlights important aspects of the validation of chromatographic methods for endogenous analytes.

Quantitative determination of endogenous compounds in biological samples using chromatographic techniques

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/0014-5793%2891%2980330-6

Amino acid derivatization and analysis in five minutes

Interaction of protein domains in the assembly and mechanism of 2-oxo acid dehydrogenase multienzyme complexes.- Probing the active site of mammalian pyruvate dehydrogenase.- Role of the E2 core in the dominant mechanisms of regulatory control of mammalian pyruvate dehydrogenase complex.- Lipoamide dehydrogenase.- Plant pyruvate dehydrogenase complexes.- Regulation of the pyruvate dehydrogenase complex during the aerobic/anaerobic transition in the development of the parasitic nematode, Ascaris suum.- Structure, function and assembly of mammalian branched-chain ?-ketoacid dehydrogenase complex.- Lipoylation of E2 component.- Pyruvate dehydrogenase phosphatase.- The mitochondrial ?-ketoacid dehydrogenase kinases: Molecular cloning, tissue-specific expression and primary structure analysis.- Shorter term and longer term regulation of pyruvate dehydrogenase kinases.- Hormonal and nutritional modulation of PDHC activity status.- Regulation of branched-chain ?-keto acid dehydrogenase complex in rat liver and skeletal muscle by exercise and nutrition.- Dephosphorylation of PDH by phosphoprotein phosphatases and its allosteric regulation by inositol glycans.- Long-term regulation and promoter analysis of mammalian pyruvate dehydrogenase complex.- The sperm-specific pyruvate dehydrogenase E1? genes.- Molecular defects of the branched-chain ?-keto acid dehydrogenase complex: maple syrup urine disease due to mutations of the E1? or E1? subunit gene.- Human defects of the pyruvate dehydrogenase complex.- Multigenic basis for maple syrup urine disease with emphasis on mutations in branched chain dihydrolipoyl acyltransferase.- Structure and chromosomal localization of the human 2-oxoglutarate dehydrogenase gene.- Pyruvate dehydrogenase complex as an autoantigen in primary biliary cirrhosis.

Alpha-Keto Acid Dehydrogenase Complexes

Books, Reviews, and Symposia Proceedings 515R Theory and Optimization 516R Theory 516R Optimization 517R Data Analysis 520R Stationary Phase Classification 520R Retention/Solute-Stationary Phase Interactions 521R Modeling/Peak Characterization/Smoothing 521R Calibration and Curve Fitting 521R Deconvolution 521R Factor Analysis 521R Miscellaneous Fundamental Studies 521R Pharmacological and Biological Applications 522R Normal Phase 522R Reversed-Phase 523R Mobile Phase Studies 524R Stationary-Phase Studies 525R Biopolymer Separations 527R Column Packings 527R Reversed Phase 529R Hydrophobic and Hydrophilic Interaction Chromatography 531R

Liquid chromatography: theory and methodology.

Measurement of plasma and urine amino acids by high-performance liquid chromatography with electrochemical detection using phenylisothiocyanate derivatization.

Cytidine deaminase is an enzyme of nucleic acid metabolism, the measurement of which has been proposed as a useful test for the early detection of pre-eclamptic toxaemia in pregnancy. The enzyme converts the nucleoside cytidine to uridine, with the release of ammonia, and it is the measurement of this latter compound that forms the basis of the conventional methods for the assay of cytidine deaminase. The low activity of the enzyme requires long incubation times, which in turn increase the possibility of contamination by exogenous ammonia. We have developed a new method for determining cytidine deaminase activity, utilising high performance liquid chromatography to measure the production of uridine. This method uses much shorter incubation times and is unaffected by ammonia contamination. This paper describes the development of the method and its comparison with the established assay. The relative merits of each are discussed. Finally, the adaptation of incubation and chromatographic conditions, in order to measure other enzymes of nucleic acid metabolism which are of clinical interest, is briefly mentioned.

Determination of plasma cytidine deaminase activity by HPLC

A method for the simultaneous measurement of vanillylmandelic acid, homovanillic acid and 5-hydroxyindoleacetic acid in urine is described. Based on reversed-phase liquid chromatography with electrochemical detection, the procedure employs isocratic elution, thus making it suitable for use in the less well-equipped clinical or research laboratory. A simple extraction of the acids from acidified urine into ethyl acetate, is followed by evaporating to dryness a portion of the organic layer, and redissolving the residue in chromatographic mobile phase. Up to 20 samples can be analysed in a single working day. The method is validated and the results obtained are compared with refereence methods. The cause of contamination of the glassy carbon surface of the working electrode is investigated, and a simple electrochemical pretreatment is described that overcomes this problem. Finally, the extra clinical information that can be derived from multi-metabolite assays is considered.

Simultaneous liquid chromatographic determination of vanillylmandelic acid, homovanillic acid, and 5-hydroxy-3-indoleacetic acid in urine, using isocratic elution and electrochemical detection.

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Measurement of plasma and urine amino acids by high-performance liquid chromatography with electrochemical detection using phenylisothiocyanate derivatization.

Determination of plasma cytidine deaminase activity by HPLC

Simultaneous liquid chromatographic determination of vanillylmandelic acid, homovanillic acid, and 5-hydroxy-3-indoleacetic acid in urine, using isocratic elution and electrochemical detection.