Cytochrome oxidase of Nitrobacter agilis: isolation by hydrophobic interaction chromatography

Cytochrome oxidase has been purified from Nitrobacter agilis using hydrophobic interaction chromatography. The purified preparation contained 3-5% phospholipid and migrated as a single band during polyacrylamide gel electrophoresis under nondissociating conditions, but appeared as three bands in the presence of sodium dodecyl sulfate and 6 M urea. These three bands corresponded to molecular weights of 37 000, 25 000, and 13 000. The absorption spectra of cytochrome oxidase isolated from Nitrobacter were similar to those reported for a-type cytochrome oxidase from other sources and exhibited absorption maxima at 420 and 600 nm when oxidized and 443 and 606 nm when reduced. The purified enzyme reacted both with horse heart and Nitrobacter cytochrome c. The enzymatic activity depended upon the pH of reaction mixture, with the maximum activity at pH 6.5 and 7.5 for Nitrobacter and horse heart cytochrome c, respectively. The activity of the purified enzyme was inhibited by cyanide, azide, and diethyl dithiocarbamate.     

1,4-Methylhistamine is a specific substrate for type B monoamine oxidase

1,4-Methylhistamine was characterized as substrate for monoamine oxidase (MAO) in rat liver mitochondria. The $\text{K}$_m and $\text{V}$_max values were 38.8 μM and 6.33 nmoles/mg protein/60 min, respectively. The inhibition experiments with clorgyline and deprenyl, the selective inhibitors for type A and type B MAO, showed that 1,4-methylhistamine was specific for type B MAO.     

13C and 1H NMR studies of helix-coil transition of poly(β-benzyl-L-aspartate) and poly(γ-benzyl-L-glutamate): Behavior in nonprotonating solvent mixtures,and origin of solvent-induced chemical shift

From the results of ¹³C-nmr measurement of poly(β-benzyl-L -aspartate) and its model compounds in dimethyl sulphoxide/deuterated chloroform mixtures, it was found that the side chain of poly(β-benzyl-L -aspartate) is solvated by dimethyl sulphoxide in the region more than dimethyl sulphoxide 20% (v/v), where the backbone maintains the α-helix. The chemical shift differences in the benzyl group carbons of poly(γ-benzyl-L -glutamate) (trifluoroacetic acid/deuterated chloroform) accompanied by the helix-coil transition, originate from the interaction between the ester group of the side chain and trifluoroacetic acid. The chemical shift difference in the ester carbon is similar. On the other hand, the chemical shift differences of the side-chain carbons in the alkyl portion (C^β, C^γ) originate not only from the interaction between the ester group of the side chain and trifluoroacetic acid, but also from some other unknown factors. The chemical shift differences of the side-chain carbons of poly(β-benzyl-L -aspartate) originate from the interaction between the ester group of the side chain and trifluoroacetic acid.     

Aminoacylase pellets.

Aminoacylase was immobilized on the mycelium pellets of Aspergillus ochraceus by using albumin and glutaraldehyde. No difference in the optimum pH was observed between native aminoacylase and aminoacylase pellets. The aminoacylase pellets were stable in pH 4-8 but they were unstable in alkaline conditions. The aminoacylase pellets were more stable against heavy metal ions and inhibitors than native aminoacylase. However, the degree of the activation of aminoacylase with cobalt ion decreased with the immobilization. It was suggested that most of aminoacylase was covalently coupled to the mycelium with glutaraldehyde.     

Electric field control of lipase membrane activity

Lipase (EC 3.1.1.3., from Pseudomonas sp.) was entrapped in collagen membrane containing liquid crystal (4-methoxybenzilidene-4′-n-butylaniline). The activity of the lipase–liquid crystal membrane at an applied voltage of 4 V was 3.4 compared to a membrane tested without imposition of an external electric field. A linear relationship was observed between the activity of the lipase–liquid crystal membrane and the current. The apparent Michaelis constant (K′_m) of the lipase–liquid crystal membrane under electric field was identical to that of the membrane under ordinary condition. Activation of the lipase–liquid crystal membrane was observed repeatedly, i.e., activation in the presence of an electric field and reversion to a basal level upon removal of the field occurred cyclically. Activity control of immobilized enzymes is desirable for switching devices of a bioreactor. Possible mechanisms of the lipase activation by electric field are discussed.     

Dye-coupled electrode system for the rapid determination of cell populations in polluted water.

We determined cell populations in polluted waters by using a fuel cell-type electrode. The electrode was constructed from a platinum anode, a silver peroxide cathode, and a membrane filter for retaining microorganisms. The principle of cell number determination is based on sensing a redox dye reduced by the microorganisms with the electrode. Sample solutions containing microorganisms were membrane filtered, and the resulting filter containing microbial cells was attached to the surface of a platinum anode. The electrode was immersed in phosphate buffer solution (0.05 M, pH 7) containing a redox dye (2,4-dichlorophenol-indophenol), and the current generated was measured. The response time of the electrode system was 10 to 20 min, and the current generated was proportional to cell populations above 10(4) cells/ml.     

Serotonin in neuroblastoma × glioma NG108-15 hybrid cells

Mouse neuroblastoma × rat glioma NG108-15 hybrid cells contain a considerable amount of serotonin, and possess small but significant tryptophan hydroxylase activity. The results suggest that NG108-15 hybrid cells are serotonergic, in addition to the known cholinergic property.     

Acidic glycosphingolipids of human amnion

Six major acidic glycosphingolipids were isolated from human amnion using DEAE Sephadex A-25 and silica beads column chromatography. The structures of these glycosphingolipids were determined by methylation analysis, TLC immunostaining and/or negative ion FAB-MS, and were concluded to be II3 alpha NeuAcLacCer(GM3), IV3 alpha NeuAcnLc4-Cer (sialyl[alpha 2-3]paragloboside), IV6 alpha NeuAcnLc4Cer (sialyl[alpha 2-6]paragloboside), IV3 alpha NeuAcIII4 alpha FucLc4Cer (sialyl Lea), VI3 alpha NeuAcnLc6Cer (i-ganglioside) and II3 alpha (NeuAc alpha 2----8NeuAc)LacCer (GD3). In addition, several minor glycosphingolipids were detected with specific monoclonal antibodies, including glycolipids with NeuAc alpha 2-3Gal beta 1-4GlcNAc-beta 1- or NeuAc alpha 2-6Gal beta 1-4GlcNAc beta 1- determinant. Our results show that the glycosphingolipids of human amnion are characterized by having mainly type II chain analogues and onco-fetal antigens.