摘要:

AbstractDespite numerous applications both in industry and in analytical chemistry, immobilized enzyme technology has encountered only limited success in modern liquid chromatography. The strict requirements of enzymatic reactors for high performance liquid chromatography (HPLC) (i.e., mechanical resistance, limited void volumes, high contact surface, high binding capacity, stable enzyme‐to‐matrix bond without loss of enzyme activity) are not yet fully met by commercially available products. In our laboratory, the development of post‐column reactors with immobilized alcohol oxidase on‐line with an HPLC/EC system has been undertaken. Three home‐made reactors were produced: in the first alcohol oxidase fromCandida boidiniiwas quasi‐immobilized onto an HPLC‐sized anion exchange support, in the second the enzyme was bound to a silica‐based support via Schiff's base formation, and in the third a covalent linkage to an epoxy‐activated hydroxyalkyl methacrylate material was chosen. Chemical immobilization proved superior to the ionic binding. The importance of limiting the post‐column band spreading due to the reactor void volume, by using HPLC‐sized su

ISSN:0269-3879    

DOI:10.1002/bmc.1130040603

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractSome useful high performance liquid chromatographic methods for the determination of amines, amine metabolites and amine metabolizing enzymes are described. These include the separation of tyramine in wines and beers, determination of tryptamine in urine, assay of monoamine oxidase and catechol‐O‐methyltransferase and analysis of amine‐aldehyde condensation pro

ISSN:0269-3879    

DOI:10.1002/bmc.1130040604

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractIn experimentally produced alcoholic fatty liver microsomal fatty acid composition was measured using gas chromatography. The results showed an increase in linoleic acid (18:2,n‐6) and hexadecaenoic acid (22:6,n‐3) and a decrease in arachidonic acid (20:4,n‐6) in alcohol‐fed rats. Using high performance liquid chromatographic separation of radiolabelled substrate and products, Δ9, Δ6and Δ5desaturase enzymes were assayed. The activity of Δ9and Δ5desaturase was decreased in alcohol‐fed rats and Δ6desaturase activity was similar in control and alcohol‐fed groups. These results indicated there was no causal relationship between desaturase activity and membrane fatty acid changes. Increased amounts of eicosatrienoic acid (20:3,n‐9) in rats fed<5% fat were observed in both control and alcohol‐fed rats. The results indicated that essential fatty acid deficiency was not due t

ISSN:0269-3879    

DOI:10.1002/bmc.1130040605

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractA simple isocratic high performance liquid chromatographic method for the simultaneous measurement ofS‐adenosylmethionine (SAM) andS‐adenosylhomocysteine (SAH) in animal tissues is described. The direct injection of perchloric acid tissue extracts and rapid resolution of both compounds in a single run reduces any sampling and analytical errors in determining the SAM/SAH ratio, a measure of methylation reactions. The method has been used to determine changes in brain SAM/SAH ratios after exposure of rats to nitrous ox

ISSN:0269-3879    

DOI:10.1002/bmc.1130040606

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractCatechol‐O‐methyltransferase (COMT) and aromatic L‐amino acid decarboxylase (AADC) activities were determined in human gastrointestinal samples. L‐dopa was used as the substrate and the reaction products 3‐O‐methyldopa (3OMD) and dopamine were separated by reversed phase HPLC and detected by electrochemical or UV detection. COMT activities varied between 40–350 pmol/mg/min and AADC activities between 100 – 3300 pmol/mg/min in different parts of the gastrointestinal tract. COMT inhibitors nitecapone (OR‐462) and OR‐611 effectively inhibited human gastrointestinal COMT activity in vitro, the IC50values ranging from 10–20 nM and 5–75 nM, respectively. In vitro carbidopa inhibited AADC slightly more effec

ISSN:0269-3879    

DOI:10.1002/bmc.1130040607

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractHistamine and itsNτ‐methyl derivative can be separated from perchloric acid extracts of rat brain by high performance liquid chromatography on a C18column under isocratic conditions eluting with 0.1 M sodium phosphate buffer containing 0.19 mM sodium dodecyl sulphate and 25% methanol. Using electrochemical detection, histamine andNτ‐methylhistamine can be detected at levels of less than 40 pg/μL tissue extract (<1 pmol). The retention times for histamine andNτ‐methylhistamine were 15 min and 23 min, respectively, at a flow rate of 1.2 mL/min, and both compounds eluted as acceptably sharp peaks. The concentrations of histamine andNτ‐methylhistamine in brain from seven‐day‐old rats were found to be very similar to those obtained by other analy

ISSN:0269-3879    

DOI:10.1002/bmc.1130040608

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe activities of 5‐aminolaevulinate dehydrase (ALA‐D), hydroxymethylbilane synthase (HMB‐S), uroporphyrinogen III synthase (URO‐S) and uroporphyrinogen decarboxylase (URO‐D) in the erythrocytes of alcoholics were assayed and compared with those in controls and abstaining alcoholics. The HMB‐S and URO‐S activities in alcoholics were significantly higher than the controls and there were significant correlations between enzyme activities and mean corpuscular volume (MCV). Alcoholics abstaining from alcohol over a nine‐month period showed a return to normal enzyme activities in parallel with the normalization of their MCV. Abstaining alcoholics thus all had normal HMB‐S and URO‐S activities. The ALA‐D and URO‐D activities of alcoholics were not significantly different from controls or from abstaining alcoholics. Alcohol appears to have a selective effect on the haem biosynthetic

ISSN:0269-3879    

DOI:10.1002/bmc.1130040609

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe activities of coproporphyrinogen oxidase, protoporphyrinogen oxidase and ferrochelatase in liver homogenates of iron‐overloaded and acutely or chronically ethanol‐treated rats were assayed by high performance liquid chromatographic methods. Decreased coproporphyrinogen oxidase activity was found in chronically carbonyliron‐fed rats while the activities of protoporphyrinogen oxidase and ferrochelatase remained unchanged. Coproporphyrinogen oxidase and protoporphyrinogen oxidase activities in both chronically and actuely ethanol‐treated animals were not significantly different from controls. In chronically ethanol‐fed rats normal ferrochelatase activity

ISSN:0269-3879    

DOI:10.1002/bmc.1130040610

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractA rapid gradient method has been established to measure simultaneously the tissue levels ofS‐adenosylmethionine (AdoMet) andS‐adenosylhomocysteine (AdoHcy). The method involves application of a 15%–25% linear gradient of methanol over a period of 10 min to an initial mobile phase of 15% methanol with 25 mM sodium phosphate, 10 mM 1‐heptanesulfonic acid solution at pH 3.2 and a flow rate of 1 mL/min. AdoHcy elutes at 9.5 min and AdoMet at 12.6 min. The assay has a detection limit of 10 pmol and is linear in the concentration range 30–800 pmol. The method was used to assess changes in AdoMet and AdoHcy concentrations of pig tissues after seven days exposure to the anaesthetic gas nitrous oxide which irreversibly inactivates methionine synthase and induces an inability to recycle homocysteine, particularly in neural tissues. The treatment caused significant alterations in cellular AdoMet: AdoHcy ratios which were principally due to a dramatic rise in AdoHcy conce

ISSN:0269-3879    

DOI:10.1002/bmc.1130040611

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractAnalysis of small amounts of glycoproteins by high performance liquid chromatography (HPLC) and liquid secondary ion mass spectrometry (LSIMS) together with enzyme digestion has been investigated using fetuin as a model. Preliminary data indicates that 71% of the expected peptides were detected by LSIMS analysis of 200 pmol total digest. HPLC profiles of peptides and glycopeptides were obtained from 2 nmol of digest using a reversed phase (C18) column eluted in a solvent system containing TFA, water and acetonitrile. This has provided glycopeptides for subsequent oligosaccharide analysis. Strategies are reviewed for the chromatographic characterization of oligosaccharides following their release from glycopeptides by chemical and enzymatic procedures.

ISSN:0269-3879    

DOI:10.1002/bmc.1130040612

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY