Polypeptide Composition and Topology Affect Hydrogelation of Star-Shaped Poly(L-lysine)-Based Amphiphilic Copolypeptides

In this research, we studied the effect of polypeptide composition and topology on the hydrogelation of star-shaped block copolypeptides based on hydrophilic, coil poly(L-lysine)20 (s-PLL20) tethered with a hydrophobic, sheet-like polypeptide segment, which is poly(L-phenylalanine) (PPhe), poly(L-leucine) (PLeu), poly(L-valine) (PVal) or poly(L-alanine) (PAla) with a degree of polymerization (DP) about 5. We found that the PPhe, PLeu, and PVal segments are good hydrogelators to promote hydrogelation. The hydrogelation and hydrogel mechanical properties depend on the arm number and hydrophobic polypeptide segment, which are dictated by the amphiphilic balance between polypeptide blocks and the hydrophobic interactions/hydrogen bonding exerted by the hydrophobic polypeptide segment. The star-shaped topology could facilitate their hydrogelation due to the branching chains serving as multiple interacting depots between hydrophobic polypeptide segments. The 6-armed diblock copolypeptides have better hydrogelation ability than 3-armed ones and s-PLL-b-PPhe exhibits better hydrogelation ability than s-PLL-b-PVal and s-PLL-b-PLeu due to the additional cation–π and π–π interactions. This study highlights that polypeptide composition and topology could be additional parameters to manipulate polypeptide hydrogelation.

The morphological changes relationship in the small intestine mucous membrane with the dynamics of the enterocyte’s membranes polypeptide composition in cattle during the fetal period of their ontogenesis

The article presents current data on the relationship of morphological changes in the jejenum intestine mucous membrane with the dynamics of the polypeptide composition in the cattle enterocytes membranes during the fetal period of ontogenesis. The study was carried out on 80 fetuses of Holstein cattle, aged 2–9 months, with a body weight of 0.6–39 kg. It was found that during the fetal period of ontogenesis, structural transformations took place in the jejunal mucous membrane of cattle, characterized by intense morphofunctional changes in its structural components. The polypeptide composition of the jejunal enterocytes plasma membrane in cattle during the fetal period of ontogenesis was determined, in particular, in the apical and basolateral membranes, respectively, 27 and 25 protein fractions with a molecular weight of 9.6–14.2 kDa to 300 kDa were found, respectively. With the help of the correlation analysis for the received data, reliable interconnections of morphological changes in the jejunal mucous layer with the dynamics of the polypeptide composition of the cattle enterocyte’s membranes during the fetal period of ontogenesis were obtained. It has been proven that the thickness of the intestinal wall with villi and the mucous membrane with villi is directly related to the content of proteins with a molecular weight of 250 kDa and 155 kDa on the apical domain of enterocytes (P ≤ 0.01–0.001). The height of the villi is associated only with the content of polypeptides with a molecular weight of 250 kDa and 155 kDa (P ≤ 0.05–001) in the apical membrane and is inversely related to the content of polypeptides with a molecular weight of 9.6–14.2 kDa, 21 kDa, 22.5 kDa, 26 kDa, 33 kDa, 35 kDa, 170–185 kDa (P ≤ 0.01–0.001). The width of the villi is related to the content on the apical membrane of proteins with a molecular weight of 170–185 kDa and 21 kDa (P ≤ 0.05–0.01). The thickness of the intestinal wall with villi and mucous membrane with villi is associated with the content of proteins with molecular weights 155 kDa, 100 kDa, 87 kDa, 66 kDa, 52 kDa) and 43 kDa (P ≤ 0.05–0.001) on the basolateral domain of enterocytes and inversely dependent on the content of polypeptides with molecular weights of 19 kDa, 21 kDa and 31 kDa (P ≤ 0.05). The height of enterocyte villi is directly related to the content of polypeptides with a molecular weight of 155 kDa and 52 kDa (P ≤ 0,05–0,01) in the basolateral membrane and is inversely dependent on the content of polypeptides with a molecular weight of 24 kDa, 22.5 kDa and 17 kDa (P ≤ 0.05–0.001). The width of the villi of enterocytes is reliably inversely related only to the content of proteins with a molecular weight of 155 kDa on the basolateral membrane (P ≤ 0.05).

Characterization of Nora Virus Structural Proteins via Western Blot Analysis

Nora virus is a single stranded RNA picorna-like virus with four open reading frames (ORFs). The coding potentials of the ORFs are not fully characterized, but ORF3 and ORF4 are believed to encode the capsid proteins (VP3, VP4a, VP4b, and VP4c) comprising the virion. To determine the polypeptide composition of Nora virus virions, polypeptides from purified virus were compared to polypeptides detected in Nora virus infectedDrosophila melanogaster. Nora virus was purified from infected flies and used to challenge mice for the production of antisera.ORF3,ORF4a,ORF4b, andORF4cwere individually cloned and expressed inE. coli; resultant recombinant proteins purified and were used to make monospecific antisera. Antisera were evaluated via Western blot against whole virus particles and Nora virus infected fly lysates. Viral purification yielded two particle types with densities of ~1.31 g/mL (empty particles) and ~1.33 g/mL (complete virions). Comparison of purified virus polypeptide composition to Nora virus infectedD. melanogasterlysate showed the number of proteins in infected cell lysates is less than purified virus. Our results suggest the virion is composed of 6 polypeptides, VP3, VP4a, two forms of VP4b, and two forms of VP4c. This polypeptide composition is similar to other small RNA insect viruses.

Protein composition of barley seeds and evaluation of their germination energy and seedling vigour under control and water stress conditions

Parental genotypes, cv. Aramir and line R567, as well as selected doubled haploid (DH) barley lines differed in the main protein fraction content in seeds. Paternal form R567 and DH line C55 were characterized by the highest protein content, while the seed of the line C23 as compared to other genotypes had the lowest content of main protein fractions. Quantitative and qualitative differences were also found in electrophoretic patterns of albumins and globulins and in polypeptide composition of hordein B and C subfractions. Spectra of these proteins were found to have more bands in the parental form R567 and DH line C55. Electrophoretic albumin + globulin patterns in the DH line C23 differed from that of the remaining barley genotypes; that type of genotype was observed to have recombination with regard to polypeptide composition of hordein B and C subfractions. The water stress delayed the seed germination into normal seedlings in all genotypes. The highest germination energy under stress conditions was characteristic of seeds from the parental form R567 and DH line C55. Seedlings of these two genotypes, as compared to the others, distinguished by the longest plumule both in control and under water stress conditions. Stress effect on the seedling vigour was expressed in a significant reduction of the seedling length, the plumule being more . Sensitive to drought than roots. A smaller reduction of the plumule length was caused by the stress in the parental form R567 and DH line C55, whereas root response to water stress was similar in all studied genotypes.

Biochemical characteristics of myofibrillar proteins of the fish parasite Isoparorchis hypselobagri (Trematoda) as survival traits in an oxygen-rich environment

We have investigated biochemical properties of myofibrillar proteins of the digenetic trematode Isoparorchis hypselobagri, which correlate with its survival in the oxygen-rich swim bladder of its host catfish (Wallago attu). The polypeptide composition of the trematode’s natural actomyosin (NAM) was striated-muscle-like, with the exception that a 98-kD polypeptide corresponding to paramyosin also existed in its sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) profiles. The profiles of immunoprecipitated NAM of the trematode support these inferences. Ca2+-sensitivity of myofibrillar contractility and Mg2+-ATPase activity of I. hypselobagri resembled troponin-linked calcium regulation of the host striated muscle. Myofibrillar permeability to water influx was insensitive to calcium chelation at neutral pH. However, the host swim bladder myofibrils displayed smooth-muscle-like polypeptide composition, pH dependence of contractility, Ca2+-sensitivity, ATPase activities, and inactivation kinetics. We propose 2 survival strategies that I. hypselobagri appears to have co-evolved: (i) fast-muscle-like musculature with exceptionally high contractility or ATPase activity; and (ii) type-II myosin resembling the host muscle in functional plasticity.