Binding of aluminium to DNA of DNP in pea root nuclei

The association of absorbed aluminium (Al) with nuclei in Alaskapea roots was shown by zonal centrifugation of isolated nuclei.In nuclei, 73% of the total incorporated Al was detected inthe DNP fraction. Furthermore, Al in DNP was found to be boundspecifically to DNA by gel filtration of dissociated DNP. (Received March 19, 1977; )     

Free amino acid changes in the cerebral cortex of experimental uremic rat

The levels of free amino acids in the cerebral cortex of acute and chronic uremic rats were examined. Amino acids significantly elevated were aspartate, glutamine, glycine, histidine, ornithine, phenylalanine, phosphoethanolamine and taurine, whereas 1-methyl histidine and 3-methyl histidine were specifically detected in uremic rats. Glutamate, arginine and carnosine disclosed a significant reduction. There was no change in the concentrations of γ-aminobutyrate and alanine. The above findings were essentially identical in both acute and chronic uremia. It was conjectured that these changes of amino acid levels in the brain might participate in the progress of uremic encephalopathy.     

N-alpha-carbobenzoxy pyroglutamyl diazomethyl ketone as active-site-directed inhibitor for pyroglutamyl peptidase

Pyroglutamyl-peptidase (L-pyroglutamyl-peptide hydrolase, EC 3.4.19.3) from Bacillus amyloliquefaciens was covalently labeled with a newly synthesized N-carbobenzoxy-L-pyroglutamyl diazomethyl ketone (Z-PGDK) and was completely inactivated. The inactivation reaction proceeded in pseudo-first order. The kinetic studies demonstrated a rate-limiting step in the inhibition reaction, resulting in the formation of a reversible (enzyme.reagent) complex. The calculated KI,app is 0.12 mM at pH 7.58. The rate of inactivation was pH dependent with an extrapolated pK value of approx. 8.6. The enzyme could be protected against inactivation by a poor substrate, pyroglutamyl-valine. The PCMB-inactivated enzyme, that could be reversibly reactivated by mercaptoethanol, failed to react with Z-PGDK. The enzyme was insensitive toward the D-isomer of Z-PGDK and other diazomethyl ketone derivatives of carbobenzoxy amino acids such as Z-L-proline and Z-L-phenylalanine. These results strongly suggest that the Z-PGDK reacts as an affinity label, presumably with a cysteine residue as the site of alkylation in pyroglutamyl-peptidase, as was reported for chloromethyl ketone derivatives of pyroglutamic acid and its N-carbobenzoxy derivative.     

A novel mannose-specific and sugar specifically aggregatable lectin from the bark of the Japanese pagoda tree (Sophora japonica)

A new D-mannose/D-glucose-specific lectin (B-SJA-II) was isolated from the bark of the Japanese pagoda tree, Sophora japonica. B-SJA-II was separated from a well known D-galactose/N-acetyl-D-galactosamine-specific lectin (B-SJA-I) by affinity chromatography on lactamyl-Sepharose, then purified by affinity chromatography on maltamyl-Sepharose. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, B-SJA-II gave four bands: subunit a-1 (Mr = 19,400), a-2 (Mr = 18,200), b-1 (Mr = 15,000), and b-2 (Mr = 13,200). Carbohydrate analysis and binding study with horseradish peroxidase-labeled lectins on the bands electroblotted onto polyvinylidene difluoride membrane showed that the three subunits other than b-2 have N-linked oligosaccharides typical of plant glycoproteins. The binding assay with horseradish peroxidase-glycoproteins revealed that all the subunits can bind sugar specifically with fetuin and asialofetuin. Furthermore, B-SJA-II aggregated to form precipitates in the absence of a specific sugar and became soluble upon addition of the specific sugar. The results indicate that each subunit has a sugar-binding site for the mannosyl core of N-linked oligosaccharide chains and recognizes each other sugar specifically to form aggregates. According to the N-terminal amino acid sequences obtained, the subunits are classified into two groups. The first group (a-1 and a-2) has an N-terminal sequence 50% identical with that of other S. japonica lectins (Hankins, C. N., Kindinger, J. I., and Shannon, L. M. (1988) Plant Physiol. 86, 67-70) and the amino acid sequence initiating at position 123 of concanavalin A (Cunningham, B. (1975) J. Biol. Chem. 250, 1503-1512), while the N-terminal sequence of the second group (b-1 and b-2) is homologous to that of concanavalin A, but completely different from that of the first group.     

Anticalmodulin drugs block the sodium gating current of squid giant axons

Summary The effects of calmodulin (CaM) antagonists (W-7, W-5, trifluoperazine, chlorpromazine, quinacrine, diazepam, propericyazine and carmidazolium) on the sodium and potassium channels were studied on the intracellularly perfused and voltage-clamped giant axon of the squid. It was found that the drugs are more potent blockers of the sodium current than of the potassium current. The drugs also reduce the sodium gating current. The blockage of the sodium and gating current can be explained by assuming that the drugs interact with the sodium gating subunit in one of its closed states. The site of action is probably the intracellular surface of the axolemma where presumably a Ca²⁺-calmodulin complex can be formed.     

Fast atom bombardment tandem mass spectrometric analysis of N-carbamoylamino acids.

Using fast atom bombardment (FAB) and tandem mass spectrometry (MS/MS), we examined 12 synthetic N-carbamoylamino acids (CAA) as tert-butyldimethylsilyl (TBDMS) derivatives. In FAB mass spectrometry and FAB MS/MS, spectra of protonated molecules for CAA provide specific cleavages involving the TBDMS carbamoyl moiety. The daughter scan spectrum of the parent ion indicated that it was useful for structural elucidation and differentiation of structural isomers of CAA. We have also identified each CAA separately in a mixture using a neutral loss scan for characteristic ions. In addition, we demonstrated that CAA in urine samples from patients with ornithine carbamoyl transferase deficiency gave collision-induced dissociation (CID) spectra which correspond well with CID spectra obtained using synthetically prepared CAA.