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31.
Several N-protected peptide amides, containing two aromatic residues spaced by one glycyl residue, have been enzymatically synthesized starting from P-Ar-OH and H-Gly-Ar-NH2 (P is the protecting group and Ar is the aromatic residue) and using α-chymotrypsin as the catalyst for the coupling step. Reactions have been carried out in water solution, at room temperature, and afford yields ranging between 20 and 75% ca. This coupling reaction occurs in a much more restricted set of conditions than the hydrolysis reaction, e.g., only within a small pH range (ca. 6.5–7.5) and with particular buffering agents. The advantages and limitations of this type of reaction, compared with conventional coupling procedures, are discussed. 相似文献
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Amino acid sequence of k Sci, the Bence Jones protein isolated from a patient with light chain deposition disease 总被引:2,自引:0,他引:2
V Bellotti M Stoppini G Merlini M C Zapponi M L Meloni G Banfi G Ferri 《Biochimica et biophysica acta》1991,1097(3):177-182
Light chain Sci was isolated from the urine of a patient affected by light chain deposition disease with an apparent exclusive localization to the kidney. Sci protein is an intact light chain: it consists of 214 amino acid residues and has an Mr of 23.65. Its complete primary structure has been determined by sequence analysis of the corresponding tryptic peptides and by partially sequencing the intact protein. Sequence comparison shows that Sci protein is strictly related to the light chains of kIIIa family (88% structural identity) which are usually expressed in autoimmune rheumatoid syndromes. Computer graphics model suggests a perturbation in k Sci three-dimensional structure due to the unusual replacement of residues 53 and 77. 相似文献
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We studied the effects of methanol, ethanol, iso-propanol, and n-propanol on the reaction of hemoglobin with oxygen at various temperatures. The analysis of the results in terms of the Monod-Wyman-Changeux model allowed determination of the overall contribution of the alcohols to the standard enthalpy and entropy differences between the T and R states of hemoglobin. A phenomenological approach allowed us to obtain separately the contributions related to the variations of the bulk dielectric constant of the solvent (bulk electrostatic contributions) and the contributions related to other effects (non-bulk-electrostatic contributions). The values of non-bulk-electrostatic contributions to ΔΔH and ΔΔS supported the suggestion that these contributions are mainly related to protein-solvent hydrophobic interactions. 相似文献
37.
The sampling of Ciliates performed in a little experimental torrent through two years, showed a great similarity of the two annual cycles. This similarity concerns both the species composition as well as the dynamics of the Ciliates populations. The basic species which affect the community structure are as follows: Ctedoctema acanthocrypta, Mesodinium acarus, Cyclidium glaucoma, Cinetochilum margaritaceum, Pleuronema coronatum, Lacrymaria pupula, Aspidisca costata and Holosticha vernalis. The dynamics of the ciliated Protozoa living in this environment seem to be influenced by the speed of the current, the temperature and the amount of dissolved organic matter in the water.
Etude de la dynamique des populations de cilies d'un torrent experimental pendant deux annees相似文献
38.
Peter Skrabal Vincenzo Rizzo Antonio Baici Felix Bangerter Pier Luigi Luisi 《Biopolymers》1979,18(4):995-1008
The 1H-nmr spectra of co-oligopeptides of tryptophan and glycine with structure H-Gly-Trp-(Gly)n-Trp-Gly-OH (n = 0–2) and those of several di- and tripeptides have been recorded at 360 MHz with CD3OD solutions containing 0.1N NaOD. The assignment of resonance signals was generally possible by comparing the spectra of structurally related peptides with each other. In order to solve the remaining ambiguities in the assignment, H-(αL,βS)(α,β-d2)Trp-OH, H-Trp-(αL,βS)(α,β-d2)Trp-OH, and H-Trp-(δ1,ε2,ζ2,ζ3,η2-d5)Trp-OH have been prepared and their spectra compared with those of the undeuterated compounds. The distribution of rotamers around the χ1 and (in two cases) χ2 torsion angles of the side chains has been obtained from the vicinal coupling constants 3J and from the long-range coupling constants 4J. These data and an analysis of the chemical shifts of the Gly-Cα protons suggest that the orientation of the aromatic side chain is influenced by the following order of decreasing interaction with the functional groups at N- and C-side: -NH2 > –NHCO– > –CONH–> –COO?. This rule does not hold for the second Trp residue of di- and tripeptides containing the -Trp-Trp- sequence, which has tentatively been attributed to steric effects. 相似文献
39.
Abstract— Antisera against the rat olfactory marker protein were prepared by injection of the homogeneous protein into a goat and a rabbit. When the antisera were tested by immunodiffusion against olfactory tissue extracts, many but not all mammalian species cross-reacted against these antisera. Immunoprecipitin titrations with the goat antiserum generally showed higher cross-reactivity against olfactory extracts from species more closely related to the rat. Human olfactory bulb extracts and non-mammalian olfactory tissue extracts did not cross-react with the antisera by either immunodiffusion tests or immunoprecipitin titrations, however, they did cross-react when tested by a competitive binding radioimmunoassay using tritium-labelled purified rat protein and the goat antibody. The olfactory marker protein which is an example of a brain protein specific to one cell, the olfactory chemoreceptor neuron, has a very wide species distribution, being present in rat, mouse, hamster, guinea-pig, sheep, cow, rabbit, pig, dog, man, frog and garfish. Therefore it presumably plays an important and unique role related to the function of this primary chemosensory neuron. 相似文献
40.
L Clerici M J Carroll M Merlini L Vercellini F Campagnari 《International journal of radiation biology and related studies in physics, chemistry, and medicine》1984,45(3):245-250
The effects of tritiated amino-acids, arginine, lysine, histidine and aspartic acid on the growth and development of two-cell mouse embryos, cultured in vitro, were investigated. The LD50 for the dibasic amino acids, measured on the third day of growth, ranged from 30 to 130 nCi/ml. This was compared with the DNA precursor, thymidine, for which the LD50 was 80 nCi/ml. 相似文献