Spectral and electrochemical properties of vanadyl hexadecafluorophthalocyanine

A vanadyl complex with perfluorinate phthalocyanine, VOPcF₁₆, was prepared. The monomer-dimer solvent dependence was confirmed based on the solvent effect for the Q-band position-that is, VOPcF₁₆ exists as a monomer in a nonpolar solvent such as benzene, but dimerizes in a polar solvent such as acetone. Electron spin resonance data also supported the solvent dependence found. In addition, the substituent effect of fluorine atoms on the redox properties was investigated by measuring the cyclic voltammograms in dichloromethane. On the reduction side, three redox couples were observed, the first two of which were assigned as being due to the reduction of the phthalocyanine ring (to LUMO), whose potentials are 0.4–0.5 V higher than those of the tetra-t-butyl and octabutoxy derivatives, VOPc(t-Bu)₄ and VOPc(O-n-Bu)₈.     

Ceramide Prevents Neuronal Programmed Cell Death Induced by Nerve Growth Factor Deprivation

Abstract: We examined the ability of ceramide and sphingomyelinase (SMase) to prevent neuronal programmed cell death (PCD). We found that a cell-permeable ceramide analogue prevented neuronal PCD when applied to established sympathetic neuron primary cultures at the time of nerve growth factor (NGF) deprivation. Other amphiphilic lipids such as oleic acid failed to prevent cell death. Exogenous SMase also showed the same effect, probably by raising the intracellular ceramide level by sphingomyelin (SM) breakdown. Phosphocholine, another hydrolytic product of SM by SMase, did not prevent cell death. Other phospholipases, such as phospholipase C and phospholipase A₂, could not prevent cell death. Given the recent findings that the SM cycle is activated to increase the intracellular ceramide level on NGF binding to the low-affinity NGF receptor (LNGFR) and that NGF binding to LNGFR suppresses apoptosis in neural cell lines, our results suggest the possibility of the SM cycle as a signaling mechanism transducing the PCD-preventing activity of NGF.     

1H-, 13C-, and 113Cd-nmr study of the Cd(II) complex of a blocked peptide,Z-Cys-Ala-Pro-His-OMe,in organic solvents

The Cd(II) complex of a peptide, Z-Cys-Ala-Pro-His-OMe was prepared and characterized by absorption, CD, ¹H-, ¹³C-, and ¹¹³Cd-nmr, and nuclear Overhauser effect spectroscopy (NOESY) spectra to show the coordination of cysteine thiolate and histidine imizazole to Cd(II) ion. The NOESY spectra in dimethyl formamide showed that the cysteine residue was in proximity to the histidine residue. These results reveal the dictation of Z-Cys-Ala-Pro-His-OMe to Cd(II) ion in solution. Temperature-dependent dissociation equilibrium of histidine imidazole in solution was observed in this complex. Structural features of the chelating peptide are discussed. © 1995 John Wiley & Sons, Inc.     

Phagocytic Activity of FRTL-5 Rat Thyroid Follicular Cells as Measured by Ingestion of Fluorescent Latex Beads

A rat thyroid cell line (FRTL-5) was used to study the phagocytic activity of thyroid follicular cells using fluorescent latex beads and flow cytometric analysis. Morphologic studies demonstrated that latex beads were engulfed and located within cytoplasmic vacuoles of thyrocytes. Flow cytometric evaluation of cell suspensions revealed high levels of fluorescence in cells engulfing latex beads. Using thyrotropin (TSH) as a stimulator of thyroid function and human interleukin-1β as an inhibitor, protocols were established for measuring the effects of these substances on either basal or TSH-induced phagocytosis. Cells exposed to latex beads over time in basal (0H) or TSH-containing medium had an increase in time-dependent phagocytic activity which was maximal after 24 or 8 h, respectively. Treatment of FRTL-5 cells with either a stimulator or an inhibitor revealed maximal change in phagocytic activity after 72 h as measured by the percentage of phagocytic cells as well as the mean fluorescence intensity. Phagocytic activity and iodide trapping by FRTL-5 cells were qualitatively similar in both sensitivity and magnitude of change in the assays used in this study. Phagocytosis of fluorescent latex beads represents a sensitive nonradioactive assay of thyrocyte function whose regulation is similar to iodide trapping.     

Genomic analysis of the mouse protamine 1, protamine 2, and transition protein 2 gene cluster reveals hypermethylation in expressing cells

To understand the role of chromatin structure in the expression of the mouse protamine 1, protamine 2, and transition protein 2 genes during spermatogenesis, we have examined the genomic organization of this cluster of ``haploid-specific' genes. As seen in the human genome, protamine 2, transition protein 2, and approximately 2.8 kb of a CpG island, hereafter called CpG island-dTP2, were clustered in a small region. Methylation analyses of this region have demonstrated that i) unlike most other tissue-specific genes, the protamine 1, protamine 2, and transition protein 2 genes were located in a large methylated domain in round spermatids, the cell type where they are transcribed, ii) the protamine 1 gene was only partially methylated in somatic cells and in testes from 7-day-old mice, and iii) the approximately 2 kb upstream and downstream of the CpG island-dTP2 were only partially methylated in somatic tissues. DNase I analysis revealed the presence of at least five strong DNase I hypersensitive sites over the CpG island-dTP2 in somatic tissues, but not in germ cells, and sequence analysis indicated that the CpG island-dTP2 is homologous to a CpG island located approximately 10.6 kb downstream of the human transition protein 2 gene. Although the nature of a CpG island-dTP2 and the function of a CpG island-dTP2-containing somatic tissue-specific DNase I hypersensitive sites in close proximity to the germ cell-specific gene cluster are unclear, the ``open' chromatin structure of the CpG island-dTP2 may be responsible for the partial methylation pattern of the flanking sequences including the transition protein 2 gene in somatic tissues. Received: 6 September 1996 / Accepted: 14 January 1997     

A novel monoantennary complex-type sugar chain found in octopus rhodopsin: occurrence of the Gal{beta}1->4Fuc group linked to the proximal N-acetylglucosaniine residue of the trimannosyl core

The N-linked sugar chains were liberated as oligosaccha-ridesfrom octopus rhodopsin by hydrazinolysis. Most of the oligosaccharideswere neutral, and separated into two major components by columnchromatography using immobilized lectins and Bio-Gel P-4. Structuralanalysis of the one major component by sequential exoglycosidasedigestion, chemical fragmentation in combination with meth-ylationanalysis revealed that it is a nonasaccharide; Man16(Gaiβ13GlcNAcβ12Man13)Manβ14GlcNAcβ14(Galβ14Fuc16)GlcNAcThis structure is quite unique in that a novel galactosylatedfucose residue is attached to the reducing terminal N-acetyl-glucosamineresidue. galactosylated Fuc N-linked sugar chain novel structure octopus rhodopsin