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91.
In this review anti-metatype antibodies are described invoking new principles in immunoassay development. Anti-metatype antibodies are immunological reagents specific for the conformation of the liganded antibody active site which do not interact with bound ligand or unliganded antibody. Relationships between anti-metatype antibody reactivity and the ligand-induced conformational state of monoclonal antibodies are reviewed with emphasis on the fluorescein hapten as a small molecule model system. One characteristic result of the interaction of anti-metatype antibodies with liganded antibodies is a significant delay in the dissociation rate (k2) of the ligand bound within the primary immune complex. The latter is an important consideration for assay development. Polyclonal and monoclonal anti-metatype antibody reagents are characterized in terms of their differential effects on the ligand dissociation rate. Anti-metatype antibody reactivity is further discussed in terms of protein-protein specificity patterns and relative interactions with idiotype-family members, structural derivatives, and site-specific mutants. Incorporation of principles inherent in the anti-metatype concept and their application to assay development are summarized.Abbreviations D2O
deuterium oxide
- Fab
50 kd antibody fragment containing VHCH1 + VLCL domains
- FITC(I)
fluorescein isothiocyanate (isomer I)
- Fv
26 kd fragment of the antibody molecule containing the variable domains of the H and L chains
- Ig
immunoglobulin
- IgG
immunoglobulin G with a mol. wt. of 150 kd.
- IgM
immunoglobulin M with a mol. wt. of 106d
- Id
idiotype
- Ka
antibody affinity (k1/k2) in M–1
- k1
second order rate of ligand association in M–1s–1
- k2
first order rate of ligand dissociation in s–1
- KD
dissociation constant or the reciprocal of the affinity constant (1/Ka)
- Mab
monoclonal antibody
- Met
metatype
- NMR
nuclear magnetic resonance
- SCA
single chain Fv derivative containing a synthetic linker between the two variable domains
- VH
variable domain of the antibody H chain
- VL
variable domain of the antibody L chain 相似文献
92.
The first 3-D open-framework TiGaPO complex, constructed from Ti(III)O(6), Ti(IV)O(6), GaO(4), and PO(4) polyhedra, contains pyridinium cations in a 1-D pore network and can be oxidized in air at 543 K with retention of the original framework structure. 相似文献
93.
We present a combined Molecular Dynamics/Quantum Chemical study of the solvent-mediated electronic coupling between an electron donor and acceptor in a C-clamp molecule. We characterize the coupling fluctuations due to the solvent motion for different solvents (acetonitrile, benzene, 1,3-diisopropyl-benzene) for the charge separation and the charge recombination processes. The time scale for solvent-induced coupling fluctuation is approximately 0.1 ps. The effect of these fluctuations on the observed rate is discussed using a recently developed theoretical model. We show that, while the microscopic charge transfer process is very complicated and its computational modeling very subtle, the macroscopic phenomenology can be captured by the standard models. Analyzing the contribution to the coupling given by different solvent orbitals, we find that many solvent orbitals mediate the electron transfer and that paths through different solvent orbitals can interfere constructively or destructively. A relatively small subset of substrate-solvent configurations dominate contributions to solvent-mediated coupling. This subset of configurations is related to the electronic structure of the C-clamp molecule. 相似文献
94.
Li W Nelson DP Jensen MS Hoerrner RS Javadi GJ Cai D Larsen RD 《Organic letters》2003,5(25):4835-4837
Imidazo[1,2-a]pyrimidine can be arylated at the 3-position with aryl bromides in the presence of base and a catalytic amount of palladium. This provides an efficient one-step synthesis of 3-arylimidazo[1,2-a]pyrimidines from the unsubstituted heterocycle. [reaction: see text] 相似文献
95.
The incorporation of explicit ions to mimic the effect of ionic strength or to neutralize the overall charge on a system in free energy calculations using molecular dynamics simulations is investigated. The difference in the free energy of hydration between two triosephosphate isomerase inhibitors calculated at five different ion concentrations is used as an example. We show that the free energy difference can be highly sensitive to the presence of explicit ions even in cases where the mutation itself does not involve a change in the overall charge. The effect is most significant if the molecule carries a net charge close to the site mutated. Furthermore, it is shown that the introduction of a small number of ions can lead to very severe sampling problems suggesting that in practical calculations convergence can best be achieved by incorporating either no counterions or by simulating at high ionic strength to ensure sufficient sampling of the ion distribution. 相似文献
96.
Cushman M Yang D Gerhardt S Huber R Fischer M Kis K Bacher A 《The Journal of organic chemistry》2002,67(16):5807-5816
A series of 6-carboxyalkyl and 6-phosphonoxyalkyl derivatives of 7-oxo-8-D-ribityllumazine were synthesized as inhibitors of both Escherichia coli riboflavin synthase and Bacillus subtilis lumazine synthase. The compounds were designed to bind to both the ribitylpurine binding site and the phosphate binding site of lumazine synthase. In the carboxyalkyl series, maximum activity against both enzymes was observed with the 3'-carboxypropyl compound 22. Lengthening or shortening the chain linking the carboxyl group to the lumazine by one carbon resulted in decreased activity. In the phosphonoxyalkyl series, the 3'-phosphonoxypropyl compound 33 was more potent than the 4'-phosphonoxybutyl derivative 39 against lumazine synthase, but it was less potent against riboflavin synthase. Molecular modeling suggested that the terminal carboxyl group of 6-(3'-carboxypropyl)-7-oxo-8-D-ribityllumazine (22) may bind to the side chains of Arg127 and Lys135 of the enzyme. A hypothetical molecular model was also constructed for the binding of 6-(2'-carboxyethyl)-7-oxolumazine (15) in the active site of E. coli riboflavin synthase, which demonstrated that the active site could readily accommodate two molecules of the inhibitor. 相似文献
97.
Pressure-supported packed capillary electrochromatography (CEC) and packed capillary high-performance liquid chromatography (pHPLC) have been coupled on-line to electrospray ionization-mass spectrometry (ESI-MS) and coordination ion spray-mass spectrometry (CIS-MS). Separation of enantiomers of barbiturates and chlorinated alkyl phenoxypropanoates were performed on a permethylated beta-cyclodextrin stationary phase by pressure-supported CEC. For on-line detection with ESI- and CIS-MS, a modified sheath-liquid interface was used. CIS-MS is a universal, novel ionization technique which improves the selectivity as well as the sensitivity. Charged complexes were formed through the addition of central complexing ions such as silver(I), cobalt(II), copper(II), and lithium(I) to the sheath flow. Advantages of CIS-MS detection compared to the ESI-MS mode are discussed. In the CIS-MS mode, increased sensitivity and high selectivity was attained through different possibilities of complexation. The superiority of pressure-supported CEC compared to pHPLC in the hyphenation with CIS-MS is demonstrated. 相似文献
98.
Mark Strobel Stewart Corn Christopher S. Lyons Gary A. Korba 《Journal of polymer science. Part A, Polymer chemistry》1987,25(5):1295-1307
ESCA and contact angle measurements were used to characterize the surfaces of Polyethylene and polypropylene films exposed to SF6, CF4, and C2F6 plasmas. None of these gases polymerized in the plasma. However, all plasma treatments grafted fluorinated functionalities directly to the polymer surfaces. SF6 plasmas graft fluorine atoms to a polyolefin surface. CF4 plasmas also react by a mechanism dominated by fluorine atoms, but with some contribution from CFx-radical reactions. Although C2F6 does not polymerize, the mechanism of grafting is still dominated by the reactions of CFx radicals. For all gases studied, the lack of polymerization is attributed to competitive ablation and polymerization reactions occurring under conditions of ion bombardment. 相似文献
99.
Sammelson RE Gurusinghe CD Kurth JM Olmstead MM Kurth MJ 《The Journal of organic chemistry》2002,67(3):876-882
An efficient and selective method for the synthesis of spiro-fused (C5)-isoxazolino-(C4)-pyrazolones (C) is reported. The process consists of utilizing the Baylis-Hillman reaction-or a quicker, stepwise MAC procedure-to give I followed by 1,3-dipolar cycloaddition and Swern oxidation to give beta-ketoesters H, which were condensed with hydrazine derivatives to provide hydrazones that underwent cycloelimination. These novel spiro-fused (C5)-isoxazolino-(C4)-pyrazolones were confirmed by spectroscopic analysis as well as single-crystal X-ray of 5. We also concluded that all condensations/cycloeliminations, except with hydrazine itself, were more effective with catalysts or higher reaction temperatures. For example, TiCl(4) was an efficient catalyst for hydrazone formation and cycloelimination with methylhydrazine, while phenyl-, benzyl-, and (4-methoxyphenyl)hydrazine reacted effectively without catalyst in refluxing xylene. 相似文献
100.
Chiang MH Antonio MR Soderholm L 《Dalton transactions (Cambridge, England : 2003)》2004,(21):3562-3567
The ground state electronic properties of metal-exchanged Preyssler heteropolyoxoanions [M(n+)P(5)W(30)O(110)](n-15), in which the encapsulated M(n+) ions are the spherical, diamagnetic ions Na(+), Ca(2+), Sr(2+), Y(3+), La(3+) and Th(4+), are studied using a combination of electrochemical, optical, and NMR experiments. We have designed experiments that focus on the influence of the charge (n) of the encapsulated cations, which themselves have no redox response, and its effect upon the W-O framework MOs. As n increases, the cluster anions accept electrons into their LUMOs with increasing ease, and their lowest-energy LMCT bands reveal a corresponding blue shift, which is indicative of an increase of the LUMO-HOMO energy splitting with increasing n. (183)W NMR spectra are used to identify the atomic origin of the LUMO states, which are shown to be composed primarily of orbitals from the ring of 5 W atoms near M(n+). The cation charge correlates directly and linearly with the half-wave potentials of the first redox couples, the LMCT band energies, and the W chemical shifts. We have combined this suite of experimental results to construct an energy level diagram of the frontier MOs for the Preyssler cluster anions. In so doing, we provide a fundamental perspective that is not otherwise available on the cation's role with specific regard to the electronic behavior of the W-O orbitals. These results are expected to provide benchmarking information as theorists begin to study these large POM systems. 相似文献