Purification and Characterization of the Catalytic Domain of Protein Tyrosine Phosphatase SHP-1 and the Preparation of Anti-△SHP-1 Antibodies

This study is focused on the expression of an SH2 domain-truncated form of protein tyrosine phosphatase SHP-1(designated △SHP-1) and the preparation of its polyelonal antibodies.A cDNA fragment encoding △SHP-1 was amplified by PCR and then cloned into the pT7 expression vector.The recombinant pT7-△SHP-1 plasmid was used to transform Rosetta(DE3) E.coll cells.△SHP-1 was distributed in the exclusion body of E.coll cell extracts and was purified through a two-column chromatographic procedure.The purified enzyme exhibited an expected molecular weight on SDS-gels and HPLC gel filtration columns.It possesses robust tyrosine phosphatase activity and shows typical enzymatic characteristics of classic tyrosine phosphatases.To generate polyclonal anti-△SHP-1 antibodies,purified recombinant △SHP-1 was used to immunize a rabbit.The resultant anti-serum was subjected to purification on △SHP-1 antigen affinity chromatography.The purified polyclonal antibody displayed a high sensitivity and specificity toward △SHP-1.This study thus provides the essential materials for further investigating the biological function and pathological implication of SHP-1 and screening the inhibitors and activators of the enzyme for therapeutic drug development.     

Purification and Characterization of the Catalytic Domain of Protein Tyrosine Phosphatase SHP-1 and the Preparation of Anti-ΔSHP-1 Antibodies

This study is focused on the expression of an SH2 domain-truncated form of protein tyrosine phosphatase SHP-1（designated ΔSHP-1） and the preparation of its polyclonal antibodies. A cDNA fragment encoding ΔSHP-1 was amplified by PCR and then cloned into the pT7 expression vector. The recombinant pT7-ΔSHP-1 plasmid was used to transform Rosetta（DE3） E. coli cells. ΔSHP-1 was distributed in the exclusion body of E. coli cell extracts and was purified through a two-column chromatographic procedure. The purified enzyme exhibited an expected molecular weight on SDS-gels and HPLC gel filtration columns. It possesses robust tyrosine phosphatase activity and shows typical enzymatic characteristics of classic tyrosine phosphatases. To generate polyclonal anti-ΔSHP-1 antibodies, purified recombinant ΔSHP-1 was used to immunize a rabbit. The resultant anti-serum was subjected to purification on ΔSHP-1 antigen affinity chromatography. The purified polyclonal antibody displayed a high sensitivity and specificity toward ΔSHP-1. This study thus provides the essential materials for further investigating the biological function and pathological implication of SHP-1 and screening the inhibitors and activators of the enzyme for therapeutic drug development.     

Synthesis of Retro-γ-Ionols and the Corresponding-Ionones1

Both the direct² and the sensitized^3,4 photolyses of (E)-β-ionol (2) have been studied in some detail. In a preliminary publication⁵ we have indicated that direct photolyses of (E)-β-ionol (2) with λ = 254 nm yields (Z)-retro-γ-ionol (3) as the primary product; upon further irradiation 3 is converted into the corresponding (E)-isomer (4) which rapidly yields the bicyclic alcohol 5. A quantitative study revealed that the photoconversion of (E)-β-ionol with λ = 254 nm to 3 is about 10 times faster than the conversion of 3 into (E)-retro-γ-ionol.⁶ This rate difference thus allows the photosynthesis of 3.     

Cloning and expression of NDM-1 metallo-β-lactamase gene and study of the catalytic properties of the recombinant enzyme

A gene-expression system has been designed to express the NDM-1 metallo-β-lactamase gene in E. coli cells. This system enables the synthesis of the recombinant protein in a soluble and active form. A method for the isolation and purification of the recombinant enzyme has been developed. The yield of the homogeneous protein preparation was 10–15 mg per liter of E. coli culture medium. The catalytic parameters of the recombinant NDM-1 β-lactamase were measured for ampicillin (K_m = 185 μM and k_cat = 585 s^–1) and meropenem (K_m = 85 μM and k_cat = 160 s^–1). These values correlate well with the literature data. The catalytic parameters for the chromogenic CENTA substrate (K_m = 14 μM and k_cat = 290 s^–1) were obtained for the first time.     

Study on the alkylation reaction of guanine and N-acetylguanine and the synthesis of 1''''-C alkylated carba-DHPG analogues

The alkylation reaction of guanine and N-acetylguanine with model compounds such as isopropyl bromide or 4-heptyl tosylate were studied. The reaction conditions such as temperature, solvent, base, and catalyst were examined for their effects on the reaction rate, and the yield and regioselectivity of the coupling reaction. The highest yield was obtained by using DMSO as the solvent. The reaction proceeded in a homogenous manner to give higher yield of 9-N and 7-N substituted product in a mole ratio of 1:1. The ratio could be raised to 2:1 if dibenzo-18-crown-6 was used as a catalyst. Using the above procedure, three carba-DHPG analogues bearing different 1'-C alkyl side chains were synthesized.     

Studies of the dissociation and the protonation of TB-chlorosulphophenol

The dissociation constant of each step for TB-chlorosulphophenol has been determined by potentiometric method, and the thermodynamic constants, △G°, △H° and △S°, of the dissociation process have been calculated. The protonation constants were measured by the spectrophotometric method. The pH values of various forms of anions of the chromogenic reagent at their concentrations were also calculated.     

Radiative lifetimes of the B1Π state of LiH and LiD

The lifetimes of the B¹Π vibrational levels of LiH and LiD were measured in a molecular beam apparatus using the method of delayed coincidences. The results for LiH are: τ(υ′ = 0) = 11.4 ns, τ(υ′ = 1) = 17.0 ns, τ(υ′ = 2) = 24 ns and for LiD τ(υ′ = 0) = 11.0 ns, τ(υ′ = 1) = 14.0 ns, τ(υ′ = 2) = 21 ns. These values are in good agreement with theoretical calculations. Three new brans of the A-X system were identified.     

Synthesis and Characterization of the Crystalline Methyl α-Glycoside of the Repeating Unit of the O-Polysaccharide of Vibrio Cholerae O:1

Abstract

There are more than eighty serotypes of Vibrio cholerae, all causing disease with symptoms of Asian cholera. Systematic prevention of cholera by immunization has not yet been achieved because of a lack of a protective vaccine. Vibrio cholerae 0:1 Gramnegative bacteria occur as two immunologically distinct strains: Ogawa and Tnaba. The lipopolysaccharide (LPS) of both strains seem to contain the same 0-polysaccharide antigen consisting^3,4 of (1+2)-a-linked 4-amino-4,6-dideoxy-a-D-mannopyranosyl residues the amino groups of which are acylated with 3-deoxy-L-glycero-tetronic acid. Although the chemical structure of the 0-polysaccharides has been known5 since 1979, the synthesis of its monomeric repeating unit was reported only in 1988.     

Kinetics of the Ziegler-Natta Polymerization of 1-Octene——The Kinetics and Mechanism of the Induction period

The kinetics of the induction period in the polymerization of 1-octene catalyzed by Solvay TiCl3-alkyl aluminium was studied with a dilatometer. The induction period decreases as [TiCl3] and [M]0 increase and temperature rises. It was observed through a microscope that large catalyst particles broke up into small particles in the induction period. So a kinetic model was proposed which ascribes the induction period to the breaking up of catalyst particles under the effect of polymer, and the most of the experimental results can be explained on the basis of the model.     

Identification of acyl protein thioesterases 1 and 2 as the cellular targets of the ras-signaling modulators palmostatin b and m

Finding the target: Activity-based proteomic profiling probes based on the depalmitoylation inhibitors palmostatin?B and M have been synthesized and were found to target acyl protein thioesterase?1 (APT1) and 2 (APT2) in cells.     

Origin of the doublet at 1360 and 1340 cm−1 in the Raman spectra of tryptophan and related compounds

Raman spectra of indole, skatole, tryptophan and its derivatives including C₄-monodeuterated tryptophan were studied with special attention to the origin of the band around 1350 cm⁻¹. The band is observed as a doublet or triplet depending on the compound and solvent, which was ascribed to Fermi resonance between one fundamental and one or two combination bands of the out-of-plane bending vibrations. Removal of the interaction is seen for C₄D-tryptophan and some solutions of skatole. The assignments of the component vibrations were made based on the shifts in frequencies upon C₄-deuteration. In tryptophan derivatives the doublet (or triplet) peaks exhibit steep changes in relative intensity at the pK_a points of the dissociable groups, which is ascribed as arising from slight frequency shifts of a pK_a-sensitive component vibration. Relations between the relative intensity and environment of indole were obtained and their possible applicability to the analyses of Raman spectra of proteins is suggested.     

Submillimeter-wave and far-infrared spectroscopy of high-J transitions of the ground and ν2 = 1 states of ammonia

Complete and reliable knowledge of the ammonia spectrum is needed to enable the analysis and interpretation of astrophysical and planetary observations. Ammonia has been observed in the interstellar medium up to J=18 and more highly excited transitions are expected to appear in hot exoplanets and brown dwarfs. As a result, there is considerable interest in observing and assigning the high J (rovibrational) spectrum. In this work, numerous spectroscopic techniques were employed to study its high J transitions in the ground and ν(2)=1 states. Measurements were carried out using a frequency multiplied submillimeter spectrometer at Jet Propulsion Laboratory (JPL), a tunable far-infrared spectrometer at University of Toyama, and a high-resolution Bruker IFS 125 Fourier transform spectrometer (FTS) at Synchrotron SOLEIL. Highly excited ammonia was created with a radiofrequency discharge and a dc discharge, which allowed assignments of transitions with J up to 35. One hundred and seventy seven ground state and ν(2)=1 inversion transitions were observed with microwave accuracy in the 0.3-4.7 THz region. Of these, 125 were observed for the first time, including 26 ΔK=3 transitions. Over 2000 far-infrared transitions were assigned to the ground state and ν(2)=1 inversion bands as well as the ν(2) fundamental band. Of these, 1912 were assigned using the FTS data for the first time, including 222 ΔK=3 transitions. The accuracy of these measurements has been estimated to be 0.0003-0.0006?cm(-1). A reduced root mean square error of 0.9 was obtained for a global fit of the ground and ν(2)=1 states, which includes the lines assigned in this work and all previously available microwave, terahertz, far-infrared, and mid-infrared data. The new measurements and predictions reported here will support the analyses of astronomical observations by high-resolution spectroscopy telescopes such as Herschel, SOFIA, and ALMA. The comprehensive experimental rovibrational energy levels reported here will permit further refinement of the potential energy surface to improve ammonia ab initio calculations and facilitate assignment of new high-resolution spectra of hot ammonia.     

Spectroscopic and computational studies of α-keto acid binding to Dke1: understanding the role of the facial triad and the reactivity of β-diketones

The O(2) activating mononuclear nonheme iron enzymes generally have a common facial triad (two histidine and one carboxylate (Asp or Glu) residue) ligating Fe(II) at the active site. Exceptions to this motif have recently been identified in nonheme enzymes, including a 3His triad in the diketone cleaving dioxygenase Dke1. This enzyme is used to explore the role of the facial triad in directing reactivity. A combination of spectroscopic studies (UV-vis absorption, MCD, and resonance Raman) and DFT calculations is used to define the nature of the binding of the α-keto acid, 4-hydroxyphenlpyruvate (HPP), to the active site in Dke1 and the origin of the atypical cleavage (C2-C3 instead of C1-C2) pattern exhibited by this enzyme in the reaction of α-keto acids with dioxygen. The reduced charge of the 3His triad induces α-keto acid binding as the enolate dianion, rather than the keto monoanion, found for α-keto acid binding to the 2His/1 carboxylate facial triad enzymes. The mechanistic insight from the reactivity of Dke1 with the α-keto acid substrate is then extended to understand the reaction mechanism of this enzyme with its native substrate, acac. This study defines a key role for the 2His/1 carboxylate facial triad in α-keto acid-dependent mononuclear nonheme iron enzymes in stabilizing the bound α-keto acid as a monoanion for its decarboxylation to provide the two additional electrons required for O(2) activation.     

Franck-Condon simulation of the A1B2→X1A1 dispersed fluorescence spectrum of fluorobenzene and its rate of the internal conversion

By using three different hybrid exchange-correlation functionals containing 20%, 35%, and 50% of exact Hartree-Fock (HF) exchange of the density functional theory and its time-dependent extension plus the Hartree-Fock and the configuration interaction of single excitation methods, equilibrium geometries, and their 30 vibrational-normal-mode frequencies of the ground S(0)((1)A(1)) and the first excited S(1)((1)B(2)) states of fluorobenzene (FB) were calculated. The dispersed fluorescence spectrum and internal conversion (IC) rate of the A(1)B(2)→X(1)A(1) transition were simulated by Franck-Condon (FC) calculations within the displaced harmonic oscillator approximation plus anharmonic and distorted corrections. The simulated spectral profile is primarily described by the Franck-Condon progression from the ring-breathing modes ν(9) and ν(10) which belong to totally symmetry modes. Anharmonic corrections simultaneously improve the intensity order of 9(1)(0) and 10(1)(0) bands and diminish 1(1)(0) transition that is fairly strong in harmonic simulations. It is concluded that the amount of Hartree-Fock exchange does impact the geometries and vibrational frequencies of FB molecule, but not the relative intensities of the transitions. It is anharmonic corrections that make the relative intensities of the transitions in good agreement with experimental results. Distorted corrections could assign most of the dominant overtones of out-of-plane nontotally symmetry modes, and the results agree well with the experimental assignments. Furthermore, it was found that the internal conversion rate is dominated by three promoting modes that are computed with lowing symmetry to C(1). By choosing dephasing width as 10 cm(-1) that is consistent with spectral simulation, we obtained the lifetimes of the A(1)B(2)→X(1)A(1) de-excitation as 11 and 19 ns, respectively, from TD(B3LYP) and HF∕CIS calculations in comparison with the experimental value 14.75 ns.     

Density and temperature dependence of the relaxation of the 1Δg state of highly compressed O2 fluid

The electronic relaxation of O₂ is investigated by an absorption excitation and fluorescence detection technique. The relaxation rate constant of O₂(¹Δ_g) is measured in the density range from 10²¹ to 3 × 10²² cm⁻³ at temperatures between 90 and 295 K. The experimental results are compared with theoretical models based on the pair distribution functions of the fluid. The effects of intermolecular potentials with hard or soft cores are discussed.     

Association-Assisted Kinetics of Pentanol-1 and Heptanol-1 Oxyethylation: Kinetic Parameters of Reactions and Association Parameters of Alcohols in the Series Butanol-1–Heptanol-1

The kinetics of pentanol-1 and heptanol-1 oxyethylation in the absence and in the presence of solvents (dodecane, p-xylene, and 1,4-dioxane) is studied under the conditions of base catalysis at 80–150°C and the concentrations of the catalyst (the corresponding sodium alkoxide) and ethylene oxide in the starting mixture of 1 and 10^–3–10^–1 mol/l, respectively. The experimental results are adequately described by the rate law that takes into account the association of alcohol molecules via hydrogen bonds. A hypothesis is advanced that an associate consisting of n alcohol molecules acts as a kinetically independent species in this reaction. The kinetic and association parameters for alcohols in the C₄–C₇ series are compared with the published data.     

Temperature dependence of the relaxation rate constants of the a 1Δg and b 1Σ +g states of oxygen isotopes

The relaxation rate constants of the low-lying electronic singlet states, a ¹Δ_g and b ¹Σ⁺_g , of gaseous natural O₂ and of the isotope ¹⁸O₂ were investigated as a function of temperature from 100 to 295 K. The measured increase of the rate constants with temperature is in good agreement with a theory of electronic-to-vibrational-translational energy transfer. The significant effects of the different electronic states and of the isotope masses on the absolute values of the relaxation rate constants, which range from 1.0× 10⁻²⁰ to 3.9× 10⁻¹⁷ s⁻¹ molecule⁻¹ cm³ at 295 K, are discussed.     

The Competition between the SRN1 and the SNAr on the β-position of Porphyrin Ring

In our recently reports, a series of amphipathic β-substituted porphyrins are synthesized, And their LB films show some novel properties.^[1] During the preparation of the intermediate of amphipathic porphyrins by the reaction of 2-nitro-5, 10,15,20-tetraphenylporphyrinato copper (Ⅱ) 1 with phenoxide ion 2(eq.l), we found that the product distribution mainly relied on if the electron acceptor was added and which solvent was used. Here we will first report the influence of p-dinitrobenzene (P-DNB) to the above reaction,the influence of the solvents to this reaction and the reaction of 2-naphoxide with 1 will be reported elsewhere.     

Intra- and interpair electron correlation --Analysis of the G1 and G2 theories

The irrationality of the HLC correction in the G1 and G2 theories has been analyzed concretely and deeply. Meanwhile, how to improve the Post-HF calculation has been pointed out.