Search results for "protein conformation"
showing 10 items of 515 documents
Not Only for Egg Yolk—Functional and Evolutionary Insights from Expression, Selection, and Structural Analyses of Formica Ant Vitellogenins
2014
Vitellogenin (Vg), a storage protein, has been extensively studied for its egg-yolk precursor role, and it has been suggested to be fundamentally involved in caste differences in social insects. More than one Vg copy has been reported in several oviparous species, including ants. However, the number and function of different Vgs, their phylogenetic relatedness, and their role in reproductive queens and nonreproductive workers have been studied in few species only. We studied caste-biased expression of Vgs in seven Formica ant species. Only one copy of conventional Vg was identified in Formica species, and three Vg homologs, derived from ancient duplications, which represent yet undiscovered…
Structural factors controlling ligand binding to myoglobin: a kinetic hole-burning study.
1998
Using temperature-derivative spectroscopy in the temperature range below 100 K, we have studied the dependence of the Soret band on the recombination barrier in sperm whale carbonmonoxy myoglobin (MbCO) after photodissociation at 12 K. The spectra were separated into contributions from the photodissociated species, Mb*CO, and CO-bound myoglobin. The line shapes of the Soret bands of both photolyzed and liganded myoglobin were analyzed with a model that takes into account the homogeneous bandwidth, coupling of the electronic transition to vibrational modes, and static conformational heterogeneity. The analysis yields correlations between the activation enthalpy for rebinding and the model p…
Comparison of neutron and X-ray scattering of dilute myoglobin solutions.
1975
Experimental results obtained by neutron scattering of dilute solutions of myoglobin are compared with those obtained by X-ray scattering. X-ray scattering remains the more powerful technique at wider angles above 0.3 A−1, where neutron experiments are less accurate because of low coherent scattering probability and high incoherent background. Neutron scattering is preferable at momentum transfers below 0.2 A−1; the conditions for applying the contrast variation method for the evaluation of the three basic scattering functions, which are due to shape and internal structure, equation (3), are ideally fulfilled in this region. Furthermore, neutrons allow observation of the hydrogen-deuterium …
Identification, structure, and properties of hemocyanins from Diplopod myriapoda.
1999
Hemocyanins are copper-containing, respiratory proteins that occur in the hemolymph of many arthropod species. Here we report for the first time the presence of hemocyanins in the diplopod Myriapoda, demonstrating that these proteins are more widespread among the Arthropoda than previously thought. The hemocyanin of Spirostreptus sp. (Diplopoda: Spirostreptidae) is composed of two immunologically distinct subunits in the 75-kDa range that are most likely arranged in a 36-mer (6 x 6) native molecule. It has a high oxygen affinity (P(50) = 4.7 torr) but low cooperativity (h = 1.3 +/- 0.2). Spirostreptus hemocyanin is structurally similar to the single known hemocyanin from the myriapod taxon,…
Novel biosensoric devices based on molecular protein hetero-multilayer films
1997
We have developed a novel concept for the modification of technical surfaces with molecularly well-organized layers of bioorganic components. A molecular construction set has been used to implement this concept which is based on molecularly stratified polyelectrolyte films as a structure decoupling protein layers from solid substrates. Utilizing this technology, one can start from a number of different substrates to obtain the same surface structures, on which protein hetero-multilayer films can be prepared to functionalize the interface for (potentially very different) purposes. We have demonstrated the viability of this concept by constructing a biosensor surface that was characterized by…
Tracking the structural dynamics of proteins in solution using time-resolved wide-angle X-ray scattering
2008
We demonstrate tracking of protein structural changes with time-resolved wide-angle X-ray scattering (TR-WAXS) with nanosecond time resolution. We investigated the tertiary and quaternary conformational changes of human hemoglobin under nearly physiological conditions triggered by laser-induced ligand photolysis. We also report data on optically induced tertiary relaxations of myoglobin and refolding of cytochrome c to illustrate the wide applicability of the technique. By providing insights into the structural dynamics of proteins functioning in their natural environment, TR-WAXS complements and extends results obtained with time-resolved optical spectroscopy and X-ray crystallography.
Endothelialization of chitosan porous conduits via immobilization of a recombinant fibronectin fragment (rhFNIII7–10)
2013
Abstract The present study aimed to develop a pre-endothelialized chitosan (CH) porous hollowed scaffold for application in spinal cord regenerative therapies. CH conduits with different degrees of acetylation (DA; 4% and 15%) were prepared, characterized (microstructure, porosity and water uptake) and functionalized with a recombinant fragment of human fibronectin (rhFNIII 7–10 ). Immobilized rhFNIII 7–10 was characterized in terms of amount ( 125 I-radiolabelling), exposure of cell-binding domains (immunofluorescence) and ability to mediate endothelial cell (EC) adhesion and cytoskeletal rearrangement. Functionalized conduits revealed a linear increase in immobilized rhFNIII 7–10 with rhF…
Regulation of Calcium Channel Activity by Lipid Domain Formation in Planar Lipid Bilayers
2003
The sarcoplasmic reticulum channel (ryanodine receptor) from cardiac myocytes was reconstituted into planar lipid bilayers consisting of 1-palmitoyl-2-oleoyl-phosphatidylethanolamine (POPE) and 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) in varying ratios. The channel activity parameters, i.e., open probability and average open time and its resolved short and long components, were determined as a function of POPE mole fraction (X(PE)) at 22.4 degrees C. Interestingly, all of these parameters exhibited a narrow and pronounced peak at X(PE) approximately 0.80. Differential scanning calorimetric measurements on POPE/POPC liposomes with increasing X(PE) indicated that the lipid bilayer ente…
Patterns of Expression and Organization of Cytokeratin Intermediate Filaments
1985
Cytokeratins are a large multigene family comprising two polypeptide types, i.e. acidic (type I) and basic (type II) ones, which are distinguished on the basis of immunological, peptide mapping, mRNA hybridization, and primary amino acid sequence data. The acidic (type I) cytokeratins can be subdivided into at least two different subtypes on the basis of their carboxy-terminal sequences. Considerable interspecies conservation of sequences exists, even extending to the 3'-non-coding mRNA regions. Different pairs of type I and II cytokeratins show different resistance to dissociation in urea. Sequence differences of the type I cytokeratins containing functional domains may be an explanation o…
Nitric oxide inhibits the ATPase activity of the chaperone-like AAA+ ATPase CDC48, a target for S-nitrosylation in cryptogein signalling in tobacco c…
2012
NO has important physiological functions in plants, including the adaptative response to pathogen attack. We previously demonstrated that cryptogein, an elicitor of defence reaction produced by the oomycete Phytophthora cryptogea , triggers NO synthesis in tobacco. To decipher the role of NO in tobacco cells elicited by cryptogein, in the present study we performed a proteomic approach in order to identify proteins undergoing S-nitrosylation. We provided evidence that cryptogein induced the S-nitrosylation of several proteins and identified 11 candidates, including CDC48 (cell division cycle 48), a member of the AAA+ ATPase (ATPase associated with various cellular activities) family. In vit…