Preparative purification of adenosine deaminase from human erythrocytes by affinity chromatography

The purification of adenosine deaminase from human erythrocytes is reported. By means of classical procedures and by using affinity chromatography as the last step, the enzyme is purified 760,000-fold with a yield of 32%. The affinity resin is composed of purine riboside (nebularine) linked to Sepharose CL6B. Since the compound has no leaving group at the C-6 position the affinity gel is stable and the chromatography can be repeated several times (up to fifteen times in eight months). Purine riboside was chosen because its potency as a reversible inhibitor of adenosine deaminase is greater than that of inosine (a low-affinity inhibitor), but lower than that of erythro-9-(2-hydroxy-3-nonyl)adenine (a high-affinity inhibitor).     

Preparative chromatographic separation of neighboring lanthanides using amines as a pH adjusting additive for producing carrier-free 177Lu

Journal of Radioanalytical and Nuclear Chemistry - This study is a preliminary experiment to examine the effect of amines as additive in eluents for separating neighboring lanthanides (Lu and Yb)...     

Exogenous Spermidine Alleviates UV-Induced Growth Inhibition of Synechocystis sp. PCC 6803 via Reduction of Hydrogen Peroxide and Malonaldehyde Levels

Effects of exogenously added spermidine (Spd) to UV-treated Synechocystis sp. PCC 6803 cultures on their growth, intracellular pigments, hydrogen peroxide (H₂O₂), malonaldehyde (MDA) contents, and antioxidant enzymes were investigated. Growth inhibition of cells subjected to 1-h UV-A, UV-B, and UV-C irradiation was abolished in culture added with 0.5 mM Spd. Both chlorophyll a and carotenoid contents were decreased under UV radiations in cells grown in BG₁₁ medium. However, the contents of these two pigments were slightly increased under UV radiations in Spd-supplemented cells with the consequence of enhanced oxygen evolution. Intracellular levels of H₂O₂ and MDA generated during 1-h UV irradiation were decreased when the culture medium contained 0.5 mM Spd. The antioxidative enzymes, catalase, and superoxide dismutase had a little or no response towards Spd supplementation under UV irradiation except for some increase in superoxide dismutase activity under UV-C. Total intracellular polyamines were decreased during Spd supplementation under UV stress; however, the cells showed a drastic increase in the amount of Put under this condition. Altogether, exogenous Spd is likely a potential compound that enables Synechocystis cells to cope with UV stress.     

NMR investigations of the silanophilic interactions of alkyl-modified silica

The ¹³C NMR spin lattice relaxation times have been measured for suspensions of chemically bonded silica particles in solutions of an organic base in deuteroacetonitrile, CD₃CN, at different base concentrations. A correlation has been observed between the relaxation rates and the ratio of the amounts of base and silica in the suspension. Thus, silanophilic interactions of chemically bonded silicas can be monitored using ¹³C NMR relaxation rates. The correlation is interpreted in terms of the rapid exchange model. The method seems to have potential for the rapid and accurate determination of equilibrium isotherms.Dedicated to Professor Dr. Dr. h.c. mult. J.F.K. Huber on the occasion of his 70th birthday     

Sugar Ester Synthesis by Thermostable Lipase from <Emphasis Type="Italic">Streptomyces thermocarboxydus</Emphasis> ME168

The extracellular lipase from Streptomyces thermocarboxydus ME168 was purified to 9.5-fold with 20% yield, following concentration by acetone precipitation, ion exchange chromatography (Resource Q) and gel filtration chromatography (Superdex 200), respectively. The purified enzyme had an apparent molecular mass of 21 kDa by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The N-terminal sequence of the lipase was ASDFDDQILG and was different from most other reported lipase. The enzyme showed maximum activity at 50 °C with the half-life of 180 min at 65 °C. It showed high stability at a broad pH range of 5.5–9.5 and was thermostable at the temperature range of 25–60 °C. The K _m and V _max were 0.28 mM and 1,428 U/mg, respectively, using p-nitrophenyl palmitate as substrate. It was active toward p-nitrophenyl ester with medium to long acyl chain (C₈–C₁₆). Lipase activity was inhibited by Zn²⁺, dithiothreitol (DTT), EDTA and some organic solvents, e.g., ethanol, acetone, dioxane, acetronitrile, tert-butanol and pyridine. Immobilized crude lipase of S. thermocarboxydus ME168 on celite could be used to synthesize sugar esters from glucose and vinyl acetate, vinyl butyrate or vinyl caproate in tert-butanol:pyridine (55:45 v/v) at 45 °C with conversion yields of 93, 67 and 55%, respectively.     

Convenient Route to Alkylene Dithiophosphato Ligands: Synthesis and Crystallographic Analysis of [OCH<Subscript>2</Subscript>CMe<Subscript>2</Subscript>CH<Subscript>2</Subscript>OPS<Subscript>2</Subscript>HNEt<Subscript>3</Subscript>]

Abstract  

Triethylammonium salts of O,O′-alkylene dithiophosphato like OGOPS₂HNEt₃, [where, G = –CH₂CMe₂CH₂–(1), –CH₂CEt₂CH₂–(2), –CMe₂CH₂CHMe–(3) and –CMe₂CMe₂–(4)] have been synthesized in quantitative yield by the direct reaction of P₂S₅ with 1,2- and 1,3-substituted glycols in presence of triethylamine, Et₃N, in 1:2:2 molar stoichiometry in toluene. These have been mainly characterized by molecular weight, IR and NMR (¹H, ¹³C and ³¹P) spectroscopic studies. Single crystal X-ray structure analysis of [OCH₂CMe₂CH₂OPS₂HNEt₃] reveals that phosphorus atom is tetrahedrally bonded to two sulfur atoms and two oxygen atoms in the ring and the molecule exists as discrete cation and anion. The structure is stabilized by cation–anion N–H···S hydrogen bonded interactions. Antiparallel pattern of triethylammonium ion is sandwiched within the two-dimensional layers of the ring system.     

On a fixed point theorem of Kirk

W.A. Kirk [J. Math. Anal. Appl. 277 (2003) 645-650] first introduced the notion of asymptotic contractions and proved the fixed point theorem for this class of mappings. In this note we present a new short and simple proof of Kirk's theorem.     

Tyrosine phosphorylation of Munc18c on residue 521 abrogates binding to Syntaxin 4

Background  

Insulin stimulates exocytosis of GLUT4 from an intracellular store to the cell surface of fat and muscle cells. Fusion of GLUT4-containing vesicles with the plasma membrane requires the SNARE proteins Syntaxin 4, VAMP2 and the regulatory Sec1/Munc18 protein, Munc18c. Syntaxin 4 and Munc18c form a complex that is disrupted upon insulin treatment of adipocytes. Munc18c is tyrosine phosphorylated in response to insulin in these cells. Here, we directly test the hypothesis that tyrosine phosphorylation of Munc18c is responsible for the observed insulin-dependent abrogation of binding between Munc18c and Syntaxin 4.     

An ecological acoustic recorder (EAR) for long-term monitoring of biological and anthropogenic sounds on coral reefs and other marine habitats

Keeping track of long-term biological trends in many marine habitats is a challenging task that is exacerbated when the habitats in question are in remote locations. Monitoring the ambient sound field may be a useful way of assessing biological activity because many behavioral processes are accompanied by sound production. This article reports the preliminary results of an effort to develop and use an Ecological Acoustic Recorder (EAR) to monitor biological activity on coral reefs and in surrounding waters for periods of 1 year or longer. The EAR is a microprocessor-based autonomous recorder that periodically samples the ambient sound field and also automatically detects sounds that meet specific criteria. The system was used to record the sound field of coral reefs and other marine habitats on Oahu, HI. Snapping shrimp produced the dominant acoustic energy on the reefs examined and exhibited clear diel acoustic trends. Other biological sounds recorded included those produced by fish and cetaceans, which also exhibited distinct temporal variability. Motor vessel activity could also be monitored effectively with the EAR. The results indicate that acoustic monitoring may be an effective means of tracking biological and anthropogenic activity at locations where continuous monitoring by traditional survey methods is impractical.     

Log-polar transform-based wavelet-modified maximum average correlation height filter for distortion-invariant target recognition

In this paper, we report a log-polar transform-based filter for in-plane rotation and scale-invariant target recognition. The log-polar transform is a known space-invariant image representation used in several image vision systems to eliminate the effects of scale and rotation in an image. In case of in-plane rotation invariance, peaks shift horizontally, while in case of scale invariance, peaks shift vertically. For full out-of-plane rotation-invariance (0–360°), log-polar transformed images are used to train the wavelet-modified maximum average correlation height (WaveMACH) filter. Correlation peak height and peak-to-sidelobe ratio have been calculated as metrics of goodness of the log-polar transform-based WaveMACH filter. This filter would reduce the memory requirement for filter storage in a practical system. Simulation results have been presented.