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21.
Roy Jefferis 《MABS-AUSTIN》2013,5(5):638-640
The glycoform profile of a glycoprotein is non-templated, i.e., is not encoded within the genome or otherwise predetermined; however, it is estimated that ~50% of human genes having an open reading frame encode a –N-X-S/T- amino acid sequence, where X represents any amino acid other than proline, that comprises a potential site (sequon) for N-linked glycosylation of the translated protein. N-linked glycosylation is both a co- and post-translational modification. The complex oligosaccharide GlcNAc2Man9Glu3 may be added at a –N-X-S/T- sequon as the polypeptide chain emerges from the ribosome tunnel. Local secondary structure determines whether oligosaccharide is added and the extent of addition. Higher occupancy is observed for –N-X-T- sequons than at –N-X-S- sequons, and the efficiency of addition can be further influenced by adjacent amino acid residues. 相似文献
22.
A. Mongae G.C. Kubheka N. Moleleki L.N. Moleleki 《Letters in applied microbiology》2013,56(4):258-263
The study of plant parasitic nematodes such as Meloidogyne spp. and their interactions with phytopathogenic bacteria remains underexplored. One of the challenges towards establishing such interactions is the dependence on symptom development as a measure of interaction. In this study, mCherry was employed as a reporter protein to investigate the interaction between the soft rot Enterobacteriaceae (SRE) Pectobacterium carotovorum subsp. brasiliensis (Pcb) and root‐knot nematode (M. incognita). Pectobacterium carotovorum subsp. brasiliensis was transformed with pMP7604 generating Pcb_mCherry strain. This strain was shown to attach to the surface coat of M.incognita J2 at the optimum temperature of 28°C. This suggests that RKN juveniles may play a role in disseminating Pcb in soils that are heavily infested with Pcb. The presence of RKN juveniles was shown to play a role in introducing Pcb_mCherry into potato tubers potentially acting as a source of latent tuber infections.
Significance and Impact of the Study
This study uses fluorescent reporter protein tagging as a tool to demonstrate the interaction between root‐knot nematode (Meloidogyne incognita) and the soft rot Enterobacteriacea (Pectobacterium carotovorum subsp. brasiliensis). Introduction of Pectobacterium through wounds generated by second‐stage juveniles (J2) into potato tubers was demonstrated. These results suggest that RKN juveniles can facilitate latent infection of potato tubers in the soil. These findings have important implications in the management of RKN and SRE in seed potato production. Furthermore, this tool can be used to study other nematode–bacteria interactions that have not been previously studied. 相似文献23.
(η3-Cyclooctenyl)Co(bisphosphine) compounds react with HBF4 in the presence of alkenes with oxidation of the metal to give the novel, paramagnetic organocobalt(II) species [(η3-cyclooctenyl)Co(bisphosphine)]+BF4−, (η3-2-RC3H4)Co(bisphosphine) complexes react similarly. The Co(II) compounds form adducts with CO and NO (the latter being diamagnetic) and undergo facile chemical and electrochemical reduction. 相似文献
24.
The preparation of new palladium(II) and platinum(II) complexes derived from alpha-diphenyl ethanedione bis(thiosemicarbazone), 1, and alpha-diphenyl ethanedione bis(4-ethylthiosemicarbazone), 2, is described. The palladium complexes 3 and 4 and platinum complexes 5 and 6 have been characterized by elemental analyses, fast atom bombardment mass spectrometry (FAB(+)) and spectroscopic studies (IR, (1)HNMR). The crystal and molecular structures of the dimeric cyclopalladated compound 4 and the mononuclear platinum complex 6 have been determined by single crystal X-ray diffraction. The cytotoxic activity of the free ligands and palladium and platinum complexes against human A2780 and A2780cisR (acquired resistance to cisplatin) epithelial ovarian carcinoma cells lines is also reported. The IC(50) values for compounds 1, 5 and 6 were found to be higher than that of cisplatin but the maximum antiproliferative activity was similar. Furthermore, the compounds largely retain their activity in the A2780cisR cell line, having a much better resistance factor than cisplatin in the pair of cell lines tested. 相似文献
25.
Vibrational circular dichroism (VCD) spectroscopy was used to investigate the solution conformations of cyclosporins A, C, D, G, and H in CDCl(3), in the amide I and NH/OH-stretching regions, and their corresponding magnesium complexes in CD(3)CN, in the amide I region. VCD spectra are sensitive to the chiral arrangement of Cdbond;O and NH bonds in this cyclic undecapeptide. Calculations of molecular geometries, as well as IR and VCD intensities of model cyclosporin fragments that include the intramolecular hydrogen bonds of the crystal conformations of cyclosporins A and H (CsA and CsH), were carried out at the density functional theory (DFT; BPW91 functional/6-31G* basis set) level. The good agreement between IR and VCD spectra from experiment and DFT calculations provides evidence that the crystal conformation of CsA is dominant in CDCl(3) solution; CsH, however, assumes both an intramolecularly hydrogen-bonded crystal conformation and more open forms in solution. Comparisons of the experimental and calculated VCD spectra in the NH/OH-stretching region of the noncomplexed cyclosporins indicate that conformers with both free and hydrogen-bonded NH and OH groups are present in solution. Differences between the IR and VCD spectra for the metal-free and magnesium-complexed cyclosporins are indicative of strong interactions between cyclosporins and magnesium ions. 相似文献
26.
A mouse model for the "sudden death" and "malarial lung" syndromes is described. Mice of the C3H/z strain succumb suddenly approximately 7 days after an infection with Plasmodium berghei becomes patent, at a time when parasitemia is still moderate (6 to 8%). Death could be shown to be due to anaphylactoid shock, probably induced by soluble immune complexes. Increased vascular permeability caused transudation and leakage of serum proteins into the interstitium and the alveoli. The lungs were found to be edematous, with a fine granular precipitate in the alveoli and adherent to the vascular walls. The precipitates reacted with antiglobulins G and M, and could be shown to also contain malaria antigens and C3/4. A dramatic drop in hematocrit was recorded several hours before death, indicating the sudden release of malaria antigens. The myocardium of animals that had died very suddenly showed a patchy loss of phosphorylase activity. This loss of activity was much more extensive, and sometimes almost total, when there had been an agonal period of several (1 to 3) hours before death. In these cases the irreversibility of the myocardial damage was also indicated by the loss of activity of the dehydrogenases, as well as by typical inflammatory reactions of granulocytic and histiocytic infiltrations. The hearts thus presented a typical picture of the acute and peracute shock syndromes. In acute shock cardiac insufficiency develops so suddenly that death ensues before irreversible damage has occurred, and cardiac insufficiency can only be demonstrated by the most sensitive of enzyme histochemical means. In the present case shock was induced by the anaphylactoid activity of immune complexes with the lung as target organ. The described syndrome appears analogous to human "malarial lung." 相似文献
27.
Time-resolved fluorescence studies of tryptophan mutants of Escherichia coli glutamine synthetase: conformational analysis of intermediates and transition-state complexes. 下载免费PDF全文
W. M. Atkins J. J. Villafranca 《Protein science : a publication of the Protein Society》1992,1(3):342-355
Single tryptophan-containing mutants of low adenylylation state Escherichia coli glutamine synthetase have been studied by frequency-domain fluorescence spectroscopy in the presence of various substrates and inhibitors. At pH 6.5, the Mn-bound wild-type enzyme (wild type has two tryptophans/subunit) and the mutant enzymes exhibit heterogeneous fluorescence decay kinetics; the individual tryptophans are adequately described by a triple exponential decay scheme. The recovered lifetime values are 5.9 ns, 2.6 ns, and 0.4 ns for Trp-57 and 5.8 ns, 2.3 ns, and 0.4 ns for Trp-158. These values are nearly identical to the previously reported results at pH 7.5 (Atkins, W.M., Stayton, P.S., & Villafranca, J.J., 1991, Biochemistry 30, 3406-3416). In addition, Trp-57 and Trp-158 both exhibit an ATP-induced increase in the relative fraction of the long lifetime component, whereas only Trp-57 is affected by this ligand at pH 7.5. The transition-state analogue L-methionine-(R,S)-sulfoximine (MSOX) causes a dramatic increase in the fractional intensity of the long lifetime component of Trp-158. This ligand has no effect on the W158S mutant protein and causes a small increase in the fractional intensity of the long lifetime component of the W158F mutant protein. Addition of glutamate to the ATP complex, which affords the gamma-glutamylphosphate-ADP complex, results in the presence of new lifetime components at 7, 3.2, and 0.5 ns for Trp-158, but has no effect on Trp-57. Similar results were obtained when ATP was added to the MSOX complex; Trp-57 exhibits heterogeneous fluorescence decay with lifetimes of 7, 3.5, and 0.8 ns. Decay kinetics of Trp-158 are best fit to a nearly homogeneous decay with a lifetime of 5.5 ns in the MSOX-ATP inactivated complex. These results provide a model for the sequence of structural and dynamic changes that take place at the Trp-57 loop and the central loop (Trp-158) during several intermediate stages of catalysis. 相似文献
28.
29.
Nikolay A. Barinov Irina I. Vlasova Alexey V. Sokolov Valeria A. Kostevich Evgeniy V. Dubrovin Dmitry V. Klinov 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(12):2862-2868
Background
Metalloproteins myeloperoxidase (MPO), ceruloplasmin (CP) and lactoferrin (LF) play an important role in regulation of inflammation and oxidative stress in vertebrates. It was previously shown that these proteins may work synergetically as antimicrobial and anti-inflammatory agents by forming complexes, such as MPO-CP and LF-CP. However, interaction of metalloprotein molecules with each other has never been characterized at a single-molecule level.Methods
In this study, the pairwise interactions of MPO, CP and LF molecules were investigated at a single-molecule level using high-resolution atomic force microscopy (AFM). Highly oriented pyrolytic graphite surface (HOPG) modified with oligoglycine-hydrocarbon graphite modifier (GM) was used as a substrate for protein deposition.Results
The procedure for reliable AFM investigation of metalloproteins and their complexes has been developed. Using this procedure, we have visualized, for the first time, single MPO, CP and LF molecules, characterized the morphology of MPO-CP and LF-CP complexes and confirmed the absence of direct contacts between MPO and LF molecules. Moreover, we have revealed the novel chainlike shape of MPO-CP conjugates.Conclusions
GM-HOPG was shown to be a convenient substrate for AFM investigation of metalloproteins and their complexes. Direct AFM visualization of MPO-CP and LF-CP complexes, on the one hand, complements previous data obtained from the “bulk techniques” and, on the other hand, provides new insight into the ultrastructure of MPO-CP complexes.General significance
The obtained results contribute to the better understanding of regulation of inflammation and oxidation stress mediated by collaborative action of the metalloproteins such as MPO, CP and LF. 相似文献30.
Prasad P. Phadnis Thilo Schurr Falk Lissner Wolfgang Kaim 《Inorganica chimica acta》2005,358(9):2609-2617
Dinaphthylmethylarsine complexes of palladium(II) and platinum(II) with the formulae [MX2L2] (M = Pd, Pt; L = di(1-naphthyl)methylarsine = Nap2AsMe and X = Cl, Br, I), [M2Cl2(μ-Cl)2L2], [PdCl(S2CNEt2)L], [Pd2Cl2(μ-OAc)2L2] and [MCl2(PR3)L] (PR3 = PEt3, PPr3, PBu3, PMePh2) have been prepared. These complexes have been characterized by elemental analyses, IR, Raman, NMR (1H, 13C, 31P) and UV-vis spectroscopy. The stereochemistry of the complexes has been deduced from the spectroscopic data. The crystal structures of trans-[PdCl2(PEt3)(Nap2AsMe)] and of [Pd(S2CNEt2)2], a follow-up product, were determined. The UV-vis spectra of [MX2L2] complexes show a red shift on going from X = Cl to X = I. The complexes [PdX2L2] and [PtX2L2] are strongly luminescent in fluid solution and in the solid at ambient temperature. 相似文献