摘要:

ABSTRACTA bacterial species(Leuconostc oenos),well suited to acidic pH values, is proposed as substrate for the spectrophotometric determination of lysozyme activity. The principal advantage of this organism as the substrate is the ease of investigating lysozyme behavior at acidic pH. The sensitivity is lower than withMicrococcus luteus,but data are highly reproducible.

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1991.tb00424.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTParalytic shellfish toxin derivatives of saxitoxin (STX) are a group of nonprotein toxins associated with shellfish that are derived intracellularly from dinoflagellate algal cells such asAlexandrium catanella, A. tamarensis,andGymnodinium catenatum.Recent reports indicate that pure cultures of bacteria harbored by the dinoflagellates intracellularly are capable of producing several of the toxins. The fundamental structure is that of saxitoxin, with 17 derivatives presently recognized, all of which exhibit varying levels of sodium channel blockage of neurons, resulting in neurological symptoms and paralysis at sufficiently high dosage. The toxins can be purified using adsorption chromatography on Sephadex G‐15 or Bio‐gel P‐2 followed by cation‐exchange chromatography. The toxins are readily resolved with silica gel thin layer chromatography, and can be visualized by oxidation with H2O2resulting in highly fluorescent derivatives. In recent years the mouse bioassay has been supplemented with ELISA assays, HPLC for resolution followed by post‐column oxidative derivatization for detection and quantitation of the various derivatives, as well as a mammalian neuroblastoma cell assay, which is highly specific for sodium channel blocki

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1991.tb00425.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTTwo molecular forms of the enzyme malate dehydrogenase (MDH1and MDH2) have been purified fromDioscorea rotundatatubers. The enzymes were resolved on a DEAE‐cellulose column and found to be homogeneous with differential mobilities on polyacrylamide gels. Both enzymes appeared to be dimeric proteins with subunit molecular weights of 30, 100 ± 50 and 31,600 ± 250 for MDH1and MDH2, respectively. The enzymes exhibited maximal catalytic activity within the pH range 6.57.5 at 37C and were inhibited by oxaloacetic acid at concentrations greater than 0.25 mM as well as other naturally occurring metabolites (citric acid, isocitric acid, a‐hetoglutaric acid, succinic acid, pyruvic acid, aspartic acid, glutamic acid, ATP and ADP). The thermal stability and storability of the enzymes at different conditions were significantly diff

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1991.tb00426.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTStereospecificity of oxygen addition distinguishes lipoxygenase initiated lipid peroxidation from nonenzymatic autoxidation that produces a racemic mixture. Similarly, the positional and stereoconfiguration of lipoxygenase metabolites of un saturated fatty acids determine their precise physiological bioactivity. Teleost fish gills produce predominantly the 12 hydroxy derivative of arachidonic and eicosapentaenoic acids. Following reaction of arachidonic acid with fish gill lipoxygenase, 12‐hydroxyeicosatetraenoic acid (12‐HETE) was isolated using column chromatography and HPLC. Chiral phase HPLC revealed that the single 12(S) HETE isomer was produced by the enzyme. Proton NMR further confirmed the structure as identical to the 12(S) HETE produced in mammalian platelets and lu

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1991.tb00427.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTThe interaction of hake muscle actomyosin with triolein in 0.6 M KCl, pH 7, during frozen storage has been investigated. ATPase activity, protein solubility and relative viscosity measurements were performed. No effect of triolein on these functional properties was observed during the storage period studied. Incorporation of l‐14C triolein to the protein was found over the storage period, indicating that despite the lack of effect on functionality, lipid‐protein interaction occurs. No differences were found in the electrophoretic patterns between control and neutral lipid added samp

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1991.tb00428.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY