Computational protein design has advanced very rapidly over the last decade, but there remain few examples of artificial proteins with direct medical applications. This study describes a new ...artificial β-trefoil lectin that recognises Burkitt's lymphoma cells, and which was designed with the intention of finding a basis for novel cancer treatments or diagnostics. The new protein, called "Mitsuba", is based on the structure of the natural shellfish lectin MytiLec-1, a member of a small lectin family that uses unique sequence motifs to bind α-D-galactose. The three subdomains of MytiLec-1 each carry one galactose binding site, and the 149-residue protein forms a tight dimer in solution. Mitsuba (meaning "three-leaf" in Japanese) was created by symmetry constraining the structure of a MytiLec-1 subunit, resulting in a 150-residue sequence that contains three identical tandem repeats. Mitsuba-1 was expressed and crystallised to confirm the X-ray structure matches the predicted model. Mitsuba-1 recognises cancer cells that express globotriose (Galα(1,4)Galβ(1,4)Glc) on the surface, but the cytotoxicity is abolished.
β-propeller proteins are highly symmetrical, being composed of a repeated motif with four anti-parallel β-sheets arranged around a central axis. Recently we designed the first completely symmetrical ...β-propeller protein, Pizza6, consisting of six identical tandem repeats. Pizza6 is expected to prove a useful building block for bionanotechnology, and also a tool to investigate the folding and evolution of β-propeller proteins. Folding studies are made difficult by the high stability and the lack of buried Trp residues to act as monitor fluorophores, so we have designed and characterized several Trp-containing Pizza6 derivatives. In total four proteins were designed, of which three could be purified and characterized. Crystal structures confirm these mutant proteins maintain the expected structure, and a clear redshift of Trp fluorescence emission could be observed upon denaturation. Among the derivative proteins, Pizza6-AYW appears to be the most suitable model protein for future folding/unfolding kinetics studies as it has a comparable stability as natural β-propeller proteins.
•Development of a new β –propeller model protein that is perfectly symmetric and contains buried tryptophan residues.•The tryptophan fluorescence emission redshifts upon denaturation and allows to follow folding and unfolding of the protein.•The protein has a stability similar to those of the natural occurring β-propeller proteins.•All proteins structures have been validated using X-ray crystallography.
This study reports the X-ray crystallographic structure of the glycyl-tRNA synthetase (GlyRS) of Nanoarchaeum equitans — a hyperthermophilic archaeal species. This is the first archaeal GlyRS crystal ...structure elucidated. The GlyRS comprises an N-terminal catalytic domain and a C-terminal anticodon-binding domain with a long β-sheet inserted between these domains. An unmodified transcript of the wild-type N. equitans tRNAGly was successfully glycylated using GlyRS. Substitution of the discriminator base A73 of tRNAGly with any other nucleotide caused a significant decrease in glycylation activity. Mutational analysis of the second base-pair C2G71 of the acceptor stem of tRNAGly elucidated the importance of the base-pair, especially G71, as an identity element for recognition by GlyRS. Glycylation assays using tRNAGly G71 substitution mutants and a GlyRS mutant where Arg223 is mutated to alanine strengthen the possibility that the carbonyl oxygen at position 6 of G71 would hydrogen-bond with the guanidine nitrogen of Arg223 in N. equitans GlyRS.
•The X-ray crystallographic structure of Nanoarchaeum equitans GlyRS has been solved in this study.•This is the first crystal structure of archaeal GlyRS.•The A73 and G71 residues of the tRNAGly acceptor stem are important for glycylation.•Arg223 of GlyRS possibly interacts with the carbonyl oxygen at position 6 of G71.
In this work, a new class of totally organic fluorescent nanogel particles and their exceptionally specific behaviors based on their unique structures are introduced, which draws a sharp line from ...conventional fluorophore‐doped and fluorophore‐branched‐type particles. The nanogel particles, the diameter of which could be controlled by adjusting reaction conditions, such as the solvent system, were spontaneously fabricated with a spherical shape by direct polymerization of non‐heterocyclic aromatic compounds, such as 2,6‐dihydroxyanthracene, 2,6‐dihydroxynaphthalene, and 9,9‐bis(4‐hydroxyphenyl)fluorene with triazinane as the cross‐linker. A fluorophoric moiety formed from a polymer main chain was realized in the particle, and consequently, the resultant content of the fluorophoric moiety was around 70–80 wt % per particle. The uniqueness and versatility of the particles can be emphasized by their good compatibility with various solvents due to their amphiphilic and ampholytic swelling properties, but also by their remarkable fluorescent solvatochromism in the dispersion state. Furthermore, these behaviors were preserved even in their polymer composite system. This study also demonstrates that various fluorescent polymer films can be fabricated with emission color control due to memorization of the solvatochromism phenomenon of the dispersed fluorescent nanoparticles.
Memorizing solvatochromism: A new class of totally organic, fluorescent, spherical, and size‐controlled nanogel particles is introduced. The particles exhibited not only good compatibility with various solvents, but also remarkable fluorescent solvatochromism in the solution state. Furthermore, various emission‐color controlled polymer films were fabricated by using memorization of the solvatochromism phenomenon of the fluorescent nanoparticles.
We have engineered a metal‐binding site into the novel artificial β‐propeller protein Pizza. This new Pizza variant carries two nearly identical domains per polypeptide chain, and forms a trimer with ...three‐fold symmetry. The designed single metal ion binding site lies on the symmetry axis, bonding the trimer together. Two copies of the trimer associate in the presence of cadmium chloride in solution, and very high‐resolution X‐ray crystallographic analysis reveals a nanocrystal of cadmium chloride, sandwiched between two trimers of the protein. This nanocrystal, containing seven cadmium ions lying in a plane and twelve interspersed chloride ions, is the smallest reported to date. Our results indicate the feasibility of using rationally designed symmetrical proteins to biomineralize nanocrystals with useful properties.
Protein design: A novel artificial protein with pseudo‐six‐fold symmetry creates a nanocrystal of cadmium chloride, sandwiched between two copies of the protein (see picture). X‐ray structural evidence for the formation of the nanocrystal inside the protein is presented.
The metabolic effects of androgens and their underlying mechanisms in females have been revealed by recent studies. An excess of androgens can have adverse effects on feeding behavior and metabolic ...functions and induce metabolic disorders / diseases, such as obesity, insulin resistance, and diabetes, in women and experimental animals of reproductive age. Interestingly, these effects of androgens are not observed in ovariectomized animals, indicating that their effects might be dependent on the estrogen milieu. Central and peripheral mechanisms, such as alterations in the activity of hypothalamic factors, reductions in energy expenditure, skeletal muscle insulin resistance, and β-cell dysfunction, might be related to these androgens’ effects. J. Med. Invest. 68 : 228-231, August, 2021
We have investigated the morphology of two-dimensional monolayers of gramicidin-D (GD) and alamethicin (Al) formed on the water surface by the dropping method (DM) using surface tension measurement ...(STm), Brewster angle microscopy (BAM), and atomic force microscopy (AFM). Dynamic light scattering (DLS) revealed that GD in alcoholic solutions formed a dimeric helical structure. According to the CD and NMR spectroscopies, GD molecules existed in dimer form in methanol and lipid membrane environments. The STm results and BAM images revealed that the GD dimer monolayer was in a liquid expanded (LE) state, whereas the Al monolayer was in a liquid condensed (LC) state. The limiting molecular area (
) was 6.2 ± 0.5 nm
for the GD-dimer and 3.6 ± 0.5 nm
for the Al molecule. The AFM images also showed that the molecular long axes of both the GD-dimer and Al were horizontal to the water surface. The stability of each monolayer was confirmed by the time dependence of the surface pressure (
) observed using the STm method. The DM monolayer preparation method for GD-dimer and Al peptide molecules is a useful technique for revealing how the model biological membrane's components assemble in two dimensions on the water surface.
Objective:The effects of oocyte activation with a Ca ionophore and roscovitine (Ca+R), a selective inhibitor of M-phase promoting factor, on unfertilized oocytes after intracytoplasmic sperm ...injection (ICSI) or testicular sperm extraction (TESE)-ICSI were evaluated. Method:Oocytes without pronuclei at 18 hours after ICSI were judged to be unfertilized and were exposed to the Ca ionophore A23187 (5 ?M) with or without roscovitine (50 ?M). The activation rate was measured 3, 7, and 18 hours later. Oocytes with two polar bodies and two pronuclei with a sperm tail were judged to have been activated. Results:At 18 hours, the activation rates in the control, Ca ionophore, and Ca+R groups were 3.5% (4/112), 26.9% (7/26), and 32.1% (17/53), respectively. The activation rate of the Ca+R group was significantly higher than that of the control and similar to that of the Ca ionophore group. Among the oocytes that remained unfertilized after TESE-ICSI, the activation rates of the Ca ionophore and Ca+R groups were 22.2% (2/9) and 43.8% (7/16), respectively. Conclusions:Sequential treatment with an Ca ionophore and roscovitine activates oocytes that remain unfertilized after ICSI. In TESE-ICSI, the activation rate tended to be increased by the co-administration of roscovitine with a Ca ionophore. J. Med. Invest. 70 : 321-324, August, 2023
The interaction between anesthetic Isoflurane (Iso) and model-biomembrane on the water surface has been investigated using quartz crystal microbalance (QCM) and quartz crystal impedance (QCI) ...methods. The model-biomembranes used were dipalmitoyl phosphatidyl choline (DPPC), DPPC-palmitic acid (PA) mixture (DPPC:PA = 8:2), DPPC-Alamethicin (Al) mixture (DPPC:Al = 39:1), and DPPC-
-Lactoglobulin (
LG) mixture (DPPC:
LG = 139:1) monolayers, respectively. The quartz crystal oscillator (QCO) was attached horizontally to each monolayer, and QCM and QCI measurements were performed simultaneously. It was found that Iso hydrate physisorbed on each monolayer/water interface from QCM and changed those interfacial viscosities from QCI. With an increase in Iso concentration, pure DPPC, DPPC-PA mixed, and DPPC-Al mixed monolayers showed a two-step process of Iso hydrate on both physisorption and viscosity, whereas it was a one-step for the DPPC-
LG mixed monolayer. The viscosity change in the DPPC-
LG mixed monolayer with the physisorption of Iso hydrate was much larger than that of other monolayers, in spite of the one-step process. From these results, the action mechanism of anesthetics and their relevance to the expression of anesthesia were discussed, based on the "release of interfacial hydrated water" hypothesis on the membrane/water interface.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
PDF
