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S S Brody

Publications and source records attributed to S S Brody.

At least 19 recordsLinked to original sources
PubMed1999

Predicted structure and fold recognition for the glutamyl tRNA reductase family of proteins.

The conserved residues of glutamyl tRNA reductase (GTR) from Hordeum vulgare (GTRhorvu) were found from an alignment/pile-up of 24 homologous sequences found using BLAST searches. A multiple alignment of sequences was used to obtain a prediction of the secondary structure of the GTR's. This secondary structure was submitted to the THREADER program to find possible homologous 3D structures. To help select the template for predicting the fold for GTRhorvu, we employed both molecular-biological and biochemical information about GTRhorvu. After fitting the secondary structure of GTRhorvu to the selected template, the MODELLER program was used to determine the fold for GTRhorvu. This model was built using the B subunit of succinyl CoA synthetase, 1scuB, as a template for the 3D structure of GTRhorvu. From the predicted structure, possible regions were identified for the binding of glutamyl-tRNA, NADPH and a heme inhibitor. The predicted structure was used to propose a detailed biochemical mechanism for the GTR, involving Mg catalyzed thioester formation and reduction by NADPH to glutamate-1-semialdehyde. Sites for these reactions are identified. The predicted structure has been deposited in the Brookhaven database as ID 1b61.

Aldehyde Oxidoreductases↗
PubMed1997

Structure prediction and fold recognition for the ferrochelatase family of proteins.

An alpha/beta barrel is predicted for the three-dimensional (3D) structure of Bacillus subtilis ferrochelatase. To arrive at this structure, the THREADER program was used to find possible homologous 3D structures and to predict the secondary structure for the ferrochelatase sequence. The secondary structure was fit by hand to the selected homologous 3D structure then the MODELLER program was used to predict the fold of ferrochelatase. Molecular biological information about the conserved residues of ferrochelatase was used as the criteria to help select the homologous 3D structure used to predict the fold of ferrochelatase. Based on the predicted structure possible, ligands binding to the iron and protoporphyrin IX are discussed. The structure has been deposited in the Brookhaven database as ID 1FJI.

Algorithms↗
PubMed1992

Effects of pH on the binding of hematoporphyrin derivative to monolayer and bilayer membranes.

The effects of pH on the binding of hematoporphyrin derivative (HpD) to monolayer and bilayer membranes have been studied. Absorption spectra of HpD bound to phosphatidylcholine (PC) liposomes indicate that there is greater binding of HpD to lipid films at acidic, tumoricidal pH conditions than at normal tissue pH. These results were found to correlate with surface pressure measurements of monolayer films formed under similar conditions. Surface potential measurements in conjunction with surface pressure measurements from monolayer films suggest that at low pH (i.e. less than or equal to 6.6) porphyrin intercalates within the lipid film to reach relatively high concentrations, while at higher pH (i.e. greater than or equal to 7.4) the porphyrin preferably adsorbs to the lipid film at the monolayer/water interface.

Hematoporphyrin Derivative↗
PubMed1992

Dihydroxy-carotenoid liposomes inhibit phototoxicity in Paramecium caudatum.

The phototoxic effects of hematoporphyrin derivative, using Paramecium caudatum as a model system, are significantly reduced in the presence of carotenoid-containing liposomes. Multilammelar large or small unilammelar vesicles, containing specific carotenoids, were effective in protecting the organism, whether administered exogenously in the bathing solution, or via incubation of paramecia in starved culture media containing carotenoid liposomes. The effectiveness of the carotenoids as inhibitors of phototoxic effects was found to depend on the mode of administration, with small unilammelar being more effective than multilammelar large vesicles for all carotenoids tested. Small unilammelar vesicles containing the dihydroxy-carotenoids zeaxanthin or astaxanthin afforded the greatest protection in both exogenous and endogenous studies. The results of this study suggest that carotenoid efficacy may be determined, in part, by the environment of the carotenoid molecules.

Animals↗
PubMed1987

Use of elevated pressure to promote the difference in permeability of Adriamycin and hematoporphyrin between neoplastic and normal lung cells.

The effect of increased pressure on the permeability of Adriamycin into human lung cells was studied as a function of a combination of pressure and temperature. Normal diploid lung cells as well as cells with adenocarcinoma were subjected to elevated pressures of up to 225 bars. The penetration of Adriamycin and hematoporphyrin into the cells, were assayed by use of fluorescence and absorption spectroscopy. After cells were subjected to pressure in the presence of Adriamycin, there was a greater concentration of Adriamycin in malignant cells than in normal cells. Malignant cells subjected to a pressure of 8 bars, for 210 min at 37 degrees C were found to contain twice the concentration of Adriamycin than normal cells, under the same conditions. The present results suggest that elevated pressure techniques may serve to increase the permeability of malignant cells to antineoplastic drugs.

Cell Membrane Permeability↗
PubMed1986

A spectrofluorometer to measure difference in fluorescence spectra: a simple method for improving sensitivity.

To accurately measure small changes in fluorescence spectra a difference spectrofluorometer was designed and constructed. The instrument simultaneously measures fluorescence from two samples. Routinely, two identical samples are used; one serving as the reference while the other is subjected to experimentation. This procedure minimizes variations in fluorescence arising from instabilities in either the sensitivity of the instrument or from the sample with time.

Pigments, Biological↗
PubMed1981

Picosecond energy transfer in Porphyridium cruentum and Anacystis nidulans.

Picosecond energy transfer is measured in Anacystis nidulans and Porphyridium cruentum. Fluorescence is sensitized by a 6-ps laser flash, at 530 nm. The time dependence of fluorescence is measured with reference to the laser pulse. Fluorescence is recorded from phycoerythrin (576 nm), R-phycocyanin (640 nm), allophycocyanin (666 nm), Photosystem II chlorophyll (690 nm) and long wave length chlorophyll (715 nm). Energy transfer measurements are made at 37 degrees C, 23 degrees C, and 0 degrees C, and 77 degrees K. It is shown that the rate of energy transfer can be varied with temperature. In both A. nidulans and P. cruentum there is a sequential transfer of excitation energy from phycoerythrin to phycocyanin to allophycocyan to Photosystem II chlorophyll fluorescence. The long wavelength chlorophyll fluorescence at 715 nm, however, does not always follow a sequential transfer of excitation energy. Depending on the temperature, fluorescence at 715 nm can precede fluorescence from phycocyanin.

Cyanobacteria↗
PubMed1978

Spectral properties of chlorophyll a monolayers in the presence of an exogenous electron donor and acceptor.

Chlorophyll a monolayers are studied at a nitrogen-water interface in the presence of a reducing or oxidizing agent: sodium ascorbate and benzyl viologen, respectively. Absorption spectra of the films are measured directly on the aqueous surface. With the aid of a computer, fourth derivative and difference spectra are determined. In the presence of ascorbate, a bathochromic shift of the absorption maximum to 693 nm can be induced as compared to 683 nm for a chlorophyll monolayer without any additives. In the presence of ascorbate, chlorophyll species at 676, 712 and 750 nm (present in a pure chlorophyll monolayer) are decreased or diminished. Illumination causes no change in the position of these absorption maxima; however, there is an increase of the absorbance of the main red absorption band. In the presence of benzyl viologen there is a hypsochromic shift of the red absorption maximum to 679 nm. Chlorophyll species at 670, 694, 712 and 740 nm (present in pure chlorophyll monolayers) are decreased or diminished upon addition of benzyl viologen. Upon illumination, there is a decrease in absorbance at 686 nm. It appears that the redox reagents induce the formation of specific chlorophyll aggregates, in the interfacial system, which might be analogous to the various chlorophyll species observed in green plant photosynthesis.

Ascorbic Acid↗
PubMed1975

Surface properties of monomolecular films of oxidized and reduced cytochrome c and f.

The surface properties of monomolecular films of oxidized and reduced cytochromes f and c were measured at an air-water interface. Area/molecular (A) and surface potential (deltaV) for oxidized and reduced forms of the cytochromes were measured as a function of pH. Oxidized cyt f has a maximum for both A and deltaV at pH 7.5. At a surface pressure of 6 dyn/cm the maximum A equals 2600 plus or minus 50 A2 and the maximum deltaV equals 200 plus or minus 10 mV. Reduced cyt f as a function of pH has a minimum value for both A (2200 A2) and deltaV (95 mV). Oxidized cyt c as a function of pH has minima for A (140 A2) and deltaV (188 mV) at pH 7.0 and 7.3, respectively. On the other hand, reduced cyt has maximum values for A (220 A2) and deltaV (260 mV) at pH 7.0 and 7.3, respectively.

Animals↗
PubMed1973

Photophosphorylation by monomolecular films at an air-water interface.

An acetone extract of chloroplast particles, when layered on an aqueous surface, exhibited light-dependent phosphorylation. Studies with the firefly-tail enzyme assay, as well as with (32)P-labeled inorganic phosphate, show an initial release of adenosine triphosphate (a step that is apparently only light-triggered), followed by a light-dependent uptake of the labeled inorganic phosphate into adenosine diphosphate and adenosine triphosphate.

Journal Article↗