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Biomedical subjects

P Hunziker

Publications and source records attributed to P Hunziker.

8 recordsLinked to original sources
PubMed1992

6-pyruvoyl tetrahydropterin synthase from salmon liver: amino acid sequence analysis by tandem mass spectrometry.

The most frequent variant of atypical phenylketonuria, an inborn error of metabolism, is characterized by a low activity of the 6-pyruvoyl tetrahydropterin synthase. We purified and characterized this enzyme from salmon liver known to contain high levels. After digestion, peptides were sequenced by tandem mass spectrometry and/or automated Edman microsequence analysis. Both a free amine terminus and an N-acetylated amine terminus were found, indicating the presence of two isoforms. The peptide sequences determined here have a high degree of homology with the protein sequence deduced from cDNA for rat 6-pyruvoyl tetrahydropterin synthase (1), however, the amine termini of these proteins differ significantly.

Alcohol Oxidoreductases↗
PubMed1992

Purification and characterization of 6-pyruvoyl tetrahydropterin synthase from human pituitary gland.

6-Pyruvoyl tetrahydropterin synthase, the enzyme that catalyses the conversion of 7,8-dihydroneopterin triphosphate to 6-pyruvoyl tetrahydropterin, was purified 3,330-fold from human pituitary gland with an overall recovery of 30%. The native enzyme has a molecular mass of 68 kD and consists of four identical subunits of 16.5 kD. The pH optimum of the enzyme in Tris/HCl buffer is 7.5. The enzyme is dependent on Mg2+ and NADPH and has a Michaelis-Menten constant of 10 microM for its natural substrate, 7,8-dihydroneopterin triphosphate. The isoelectric point of the human enzyme is 4.3-4.6. The human pituitary gland enzyme is heat instable in contrast to the enzymes from human, rat and salmon liver, and Drosophila head. The amino acid composition showed remarkably high content of acidic amino acids Asp and Glu. The N-terminus was found to be blocked.

Alcohol Oxidoreductases↗
PubMed1987

Accuracy and dynamic response of disposable pressure transducer-tubing systems.

Accuracy and dynamic response of seven different disposable saline-filled transducer-tubing systems were evaluated in two configurations; a pole-mount version (60-inch tubing) and patient-mount version (12-inch tubing). Natural frequencies (Fn) and damping coefficients were measured as were pressure waveform recordings. A 0.03 ml air bubble was inserted into the different systems in close proximity to the transducer and measurements were repeated. There were dramatic changes in dynamic response with lengthening of tubing to a pole-mount configuration and air bubble additions. Only one transducer-tubing system had adequate accuracy and dynamic response in both the pole- and patient-mount version. Pressure waveforms in the pole-mount versions and with the air bubble produced systolic overshoots up to 35 mmHg. The performance characteristics dictate that the choice for a disposable transducer-tubing system must be made not only by design, but dynamic response which is directly related to clinical set-up.

Blood Pressure Determination↗
PubMed1978

[The importance of ionic strength and protein concentration in the dialysis performance of autoanalyzer systems for the enzymatic determination of uric acid (author's transl)].

An earlier method for the determination of uric acid (this journal 13, 89--96, (1975) was reevaluated. It was confirmed that it is necessary to add NaCl and a detergent to the wash fluid in order to obtain full sensitivity and linearity. Protein components in the samples or in secondary standard solutions also increase sensitivity and straighten the calibration curve of primary standard solutions. The effects are compared with results reported in the literature, and the possible mechanisms of these effects are discussed.

Autoanalysis↗
PubMed1975

[A mechanized enzymic method for the determination of uric acid (author's transl)].

A continuous flow method is described for the determination of uric acid in serum using uricase and peroxidase, with omicron-dianisidine as the chromogen. The method can be used with single channel systems and with the multichannel system SMA 12/60 (Technicon). The new method was compared with six other manual and mechanized methods for the dosage of uric acid, and the results were analyzed statistically. The results from all the enzymic methods showed a good correlation, whereas the "chemical oxidation" methods showed systematic deviations.

Autoanalysis↗
PubMedDate not supplied

Mammalian metallothionein.

Chemical, spectroscopic, and structural studies have established the metallothioneins (MTs) to be a widely occurring family of polypeptidic bioinorganic structures. They are distinguished by an extremely high metal (Zn, Cd, Cu) and Cys content and by the arrangement of these components in metal-thiolate clusters. By structural criteria the MTs have recently been subdivided into three classes (Fowler et al., Experientia Suppl. 52, 19-22, 1987). Class I MTs include mammalian MTs and related forms. Class II MTs display no such relationships, and Class III MTs are atypical polypeptides made up of repetitive gamma-glutamylcysteinyl units. Amino acid sequences of over 50 MTs are now known. In mammals, over 55% of the residues, including the 20 Cys, are conserved. Mammalian MTs are genetically polymorphous. Thus, in human tissues and cell lines closely related structures of ten functional isoMTs have been determined either by amino acid or nucleotide sequencing. A comparable degree of polymorphism also exists in the rabbit. Mammalian MTs have been inferred to bind a total of seven bivalent metal ions (Me) through thiolate coordination in two separate clusters, i.e., Me(II)3(Cys)9 and Me(II)4(Cys)11. This two-cluster model has now fully been confirmed by the spatial structures of rat MT-2 and rabbit MT-2a determined by 2D NMR spectroscopy in aqueous solution.

Amino Acid Sequence↗