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At least 631 records · Page 35Linked to original sources
PubMed1994

Purification and properties of uricase from Candida sp. and its application in uric acid analysis in serum.

The purification of uricase from Candida sp. was carried out by precipitation with ammonium sulfate then further proceeded with Sephadex G200, and DEAE-cellulose DE52 chromatographies. The specific activity of the enzyme was enhanced from 0.05-12 (U/mg protein). The purity of the enzyme was judged to be homogeneous by SDS-PAGE. Some of the general properties of enzyme were investigated. The optimum reaction pH and temperature were 8.5 and 30 degrees C, respectively. The enzyme was stable at a pH range from 8.5-9.5 and at temperatures lower than 35 degrees C. The apparent Km value of the enzyme was calculated to be about 5.26 x 10(-6) mol/L. The molecular weight was determined to be 70,000-76,000 by the gel filtration and SDS-PAGE techniques. The isoelectric point was determined to be pH 5.6. The effects of some metallic ions on enzyme activity and stability were discussed. The partial purified uricase was used in serum uric acid determination. The within-batch imprecision percentage ranged from 2.16-2.63 and the between-batch imprecision percentage ranged from 2.4-3.6. The recovery ratio were from 96-101%. The correlation among this method and Boehringer, Roche, or Biotrol enzymatic kits were Y = 1.086x-0.50 (r = 0.981), Ya = 0.959x-0.29 (r = 0.97), and Yb = 1.110x-0.45 (r = 0.956), respectively. A linear calibration curve was obtained at 2.5-15 mg/dL uric acid. The stability of reagents and the effects of some substances in serum were also surveyed.

Candida↗
PubMed1999

Functional analysis and molecular modeling of a cloned urate transporter/channel.

Recombinant protein, designated UAT, prepared from a cloned rat renal cDNA library functions as a selective voltage-sensitive urate transporter/channel when fused with lipid bilayers. Since we previously suggested that UAT may represent the mammalian electrogenic urate transporter, UAT has been functionally characterized in the presence and absence of potential channel blockers, several of which are known to block mammalian electrogenic urate transport. Two substrates, oxonate (a competitive uricase inhibitor) and pyrazinoate, that inhibit renal electrogenic urate transport also block UAT activity. Of note, oxonate selectively blocks from the cytoplasmic side of the channel while pyrazinoate only blocks from the channel's extracellular face. Like oxonate, anti-uricase (an electrogenic transport inhibitor) also selectively blocks channel activity from the cytoplasmic side. Adenosine blocks from the extracellular side exclusively while xanthine blocks from both sides. These effects are consistent with newly identified regions of homology to uricase and the adenosine A1/A3 receptor in UAT and localize these homologous regions to the cytoplasmic and extracellular faces of UAT, respectively. Additionally, computer analyses identified four putative alpha-helical transmembrane domains, two beta sheets, and blocks of homology to the E and B loops of aquaporin-1 within UAT. The experimental observations substantiate our proposal that UAT is the molecular representation of the renal electrogenic urate transporter and, in conjunction with computer algorithms, suggest a possible molecular structure for this unique channel.

Amino Acid Sequence↗
PubMed2005

Assay for uric acid level in rat striatum by a reagentless biosensor based on functionalized multi-wall carbon nanotubes with tin oxide.

A novel reagentless amperometric uric acid biosensor based on functionalized multi-wall carbon nanotubes (MWCNTs) with tin oxide (SnO2) nanoparticles has been developed. This was successfully applied to assay uric acid levels from an in vivo microdialysis sampling. Compared with unfunctionalized or traditional carboxylic acid (-COOH)-functionalized MWCNTs, the MWCNTs-SnO2 electrode exhibited higher electrocatalytic oxidation to uric acid. Here, MWCNTs-SnO2 may act as an efficient promoter, and the system exhibited a linear dependence on the uric acid concentration over the range from 1.0 x 10(-7) to 5.0 x 10(-4) mol L(-1). In addition, there was little ascorbic acid interference. The high sensitivity of the MWCNTs-SnO2 modified enzyme electrode enabled the monitoring of trace levels of uric acid in dialysate samples in rat striatum.

Animals↗
PubMed1997

Application of in situ hybridization, cytochemical and immunocytochemical techniques for the investigation of peroxisomes. A review including novel data. Robert Feulgen Prize Lecture 1997.

In situ hybridization, cytochemical and immunocytochemical techniques have contributed significantly to the understanding of the biology of peroxisomes, since they permit in situ demonstration of the sites of synthesis and distribution of peroxisomal proteins without the necessity of homogenization and subcellular fractionation of tissues or cultured cells. This article reviews the results of research on mammalian peroxisomal metabolism, biogenesis and proliferation in which morphological techniques have played a significant role in the elucidation of the biological problem. Some new data on peroxisomal heterogeneity and morphogenesis are included. The morphological methods applied have made it possible to characterize the differences in distribution of mRNAs encoding peroxisomal proteins in different tissues, as well as to monitor the marked heterogeneity in the protein composition and in the activity of specific enzymes in the peroxisomal population of single cells, or in tissues with complex organization (e.g. liver and kidney). In addition, the dynamic alterations and high plasticity of the peroxisomal compartment--partly dependent on contact of the peroxisomes to the microtubular network-are presented.

Animals↗