Water scaffolding in collagen: Implications on protein dynamics as revealed by solid‐state NMR

Solid‐state NMR studies of collagen samples of various origins confirm that the amplitude of collagen backbone and sidechain motions increases significantly on increasing the water content. This conclusion is supported by the changes observed in three different NMR observables: (i) the linewidth dependence on the ¹H decoupling frequency; (ii) ¹³C CSA changes for the peptide carbonyl groups, and (iii) dephasing rates of ¹H‐¹³C dipolar couplings. In particular, a nearly threefold increase in motional amplitudes of the backbone librations about C‐C^α or N‐C^α bonds was found on increasing the added water content up to 47 wt%D₂O. On the basis of the frequencies of NMR observables involved, the timescale of the protein motions dependent on the added water content is estimated to be of the order of microseconds. This estimate agrees with that from wideline T₂ ¹H NMR measurements. Also, our wideline ¹H NMR measurements revealed that the timescale of the microsecond motions in proteins reduces significantly on increasing the added water content, i.e., an ～15‐fold increase in protein motional frequencies is observed on increasing the added water content to 45 wt% D₂O. The observed changes in collagen dynamics is attributed to the increase in water translational diffusion on increasing the amount of added water, which leads to more frequent “bound water/free water” exchange on the protein surface, accompanied by the breakage and formation of new hydrogen bonds with polar functionalities of protein. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 246–256, 2014.     

Recombinant Fragment of the Extracellular Domain of Human Desmoglein 3 Fused with the Fc-Fragment of Human IgG1 Selectively Adsorbs Autoreactive Antibodies from the Sera of Pemphigus Patients

Doklady Biochemistry and Biophysics - Using the recombinant second fragment of the extracellular domain (EC2) of human desmoglein type 3 (Dsg3) as an affinity ligand, an immunosorbent was obtained...     

Isolation of highly active preparations of sarcoplasmic reticulum and Ca2-dependent ATPase from cardiac muscle]

A microsomal preparation with a high ability for Ca2+ uptake has been isolated from pigeon heart. A method of further purification of Ca2+-accumulating system of heart, based on the ability of sarcoplasmic reticulum for the energy-dependent Ca2+ accumulation in the presence of oxalate, has been developed. Upon centrifugation in the gradient of sucrose and KCl concentration the fragments of sarcoplasmic reticulum, rendered "heavy" by calcium oxalate, can be separated from foreign cell membranes. The main component of heart "calcium pump" is Ca2+-dependent ATPase (making up to about 50% of all proteins of the purified reticulum), having a molecular weight of 100.000--105.000. Specific activity of heart Ca2+-ATPase as well as the ability of purified heart sarcoplasmic reticulum for Ca2+ uptake are only slightly less than those of the skeletal muscle reticulum. The data obtained suggest that heart sarcoplasmic reticulum may be efficient for providing heart muscle relaxation.     

Chitosan nanoparticles targeted to the tumor-associated ganglioside GD2

Methodological approaches to the creation of nanoparticles based on chitosan derivatives and targeted to the GD2-positive tumor cells were developed. The GD2-specific monoclonal antibodies and their Fab-fragments and scFv-fragments were obtained and studied as vector molecules. Various methods for covalent conjugation of these molecules to the nanoparticles were also studied. It was shown that site-specific conjugation of scFv-fragments of GD2-specific antibodies to the chitosan nanoparticles by using a reagent BMPS is the optimal approach to create targeted chitosan-based nanoparticles directed to tumor-associated ganglioside GD2.     

Changes in the population structure of the red-tailed Libyan jird as affected by toxicants

The kind of the regulating agent for the quantitative control of the epidemically dangerous species depends on the concrete tasks. The poison of the critical action causes a strong, but short-time effect. The pesticide inhibiting the reproductive system of the rodents exerts long and profound influence on the population structure.