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21.
Scaling of folding times in Go models of proteins and of decoy structures with the Lennard-Jones potentials in the native contacts reveal power law trends when studied under optimal folding conditions. The power law exponent depends on the type of native geometry. Its value indicates lack of kinetic optimality in the model proteins. In proteins, mechanical and thermodynamic stabilities are correlated. 相似文献
22.
Ly Na Huynh Adama Zan Diarra Quang Luan Pham Nhiem Le-Viet Jean-Michel Berenger Van Hoang Ho Xuan Quang Nguyen Philippe Parola 《PLoS neglected tropical diseases》2021,15(9)
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been reported as a promising and reliable tool for arthropod identification, including the identification of alcohol-preserved ticks based on extracted leg protein spectra. In this study, the legs of 361 ticks collected in Vietnam, including 251 Rhiphicephalus sanguineus s.l, 99 Rhipicephalus (Boophilus) microplus, two Amblyomma varanensis, seven Dermacentor auratus, one Dermacentor compactus and one Amblyomma sp. were submitted for MALDI-TOF MS analyses. Spectral analysis showed intra-species reproducibility and inter-species specificity and the spectra of 329 (91%) specimens were of excellent quality. The blind test of 310 spectra remaining after updating the database with 19 spectra revealed that all were correctly identified with log score values (LSV) ranging from 1.7 to 2.396 with a mean of 1.982 ± 0.142 and a median of 1.971. The DNA of several microorganisms including Anaplasma platys, Anaplasma phagocytophilum, Anaplasma marginale, Ehrlichia rustica, Babesia vogeli, Theileria sinensis, and Theileria orientalis were detected in 25 ticks. Co-infection by A. phagocytophilum and T. sinensis was found in one Rh. (B) microplus. 相似文献
23.
Molecular dynamics simulations in simplified models allow one to study the scaling properties of folding times for many proteins together under a controlled setting. We consider three variants of the Go models with different contact potentials and demonstrate scaling described by power laws and no correlation with the relative contact order parameter. We demonstrate existence of at least three kinetic universality classes that are correlated with the types of structure: the alpha-, alpha-beta-, and beta- proteins have the scaling exponents of approximately 1.7, 2.5, and 3.2, respectively. The three classes merge into one when the contact range is truncated at a reasonable value. We elucidate the role of the potential associated with the chirality of a protein. 相似文献
24.
Maoyi Tian Phu D. Hoang Simon C. Gandevia Lynne E. Bilston Robert D. Herbert 《Journal of biomechanics》2010,43(5):990-993
Comprehensive characterization of stress relaxation in musculotendinous structures is needed to create robust models of viscoelastic behavior. The commonly used quasi-linear viscoelastic (QLV) theory requires that the relaxation response be independent of tissue strain (length). This study aims to characterize stress relaxation in the musculotendinous and ligamentous structures crossing the human ankle (ankle-only structures and the gastrocnemius muscle–tendon unit, which crosses the ankle and knee), and to determine whether stress relaxation is independent of the length of these structures. Two experiments were conducted on 8 healthy subjects. The first experiment compared stress relaxation over 10 min at different gastrocnemius muscle–tendon unit lengths keeping the length of ankle-joint only structures fixed. The second experiment compared stress relaxation at different lengths of ankle-joint only structures keeping gastrocnemius muscle–tendon unit length fixed. Stress relaxation data were fitted with a two-term exponential function (T=G0+G1e?λ1t+G2e?λ2t). The first experiment demonstrated a significant effect of gastrocnemius muscle–tendon unit length on G1, and the second experiment demonstrated an effect of the length of ankle-joint only structures on G2, λ1 and λ2 (p<0.05). Nonetheless, the size of effects on stress relaxation was small (ΔG/G<10%), similar to experimental variability. We conclude that stress relaxation in the relaxed human ankle is minimally affected by changing gastrocnemius muscle–tendon unit length or by changing the lengths of ankle-joint only structures. Consequently quasi-linear viscoelastic models of the relaxed human ankle can use a common stress relaxation modulus at different knee and ankle angles with minimal error. 相似文献
25.
The efficient surface patterning of oligonucleotides was accomplished onto the inner wall of fused-silica capillary tubes as well as on the surface of glass slides through oxime bond formation. The robustness of the method was demonstrated by achieving the surface immobilization of up to three different oligonucleotide sequences inside the same capillary tube. The method involves the preparation of surfaces grafted with reactive aminooxy functionalities masked with the photocleavable protecting group, 2-(2-nitrophenyl) propyloxycarbonyl group (NPPOC). Briefly, NPPOC-aminooxy silane 1 was prepared and used to silanize the glass surfaces. The NPPOC group was cleaved under brief irradiation to unmask the reactive aminooxy group on surfaces. These reactive aminooxy groups were allowed to react with aldehyde-containing oligonucleotides to achieve an efficient surface immobilization. The advantage associated with the present approach is that it combines the high-coupling efficiency of oxime bond formation with the convenience associated with the use of photolabile groups. The present strategy thus offers an alternative approach for the immobilization of biomolecules in the microchannels of "labs on a chip" devices. 相似文献
26.
Duc HN van Trommel NE Sweep FC Massuger LF Thomas CM 《The International journal of biological markers》2006,21(1):45-49
OBJECTIVE: Human chorionic gonadotropin (hCG) is widely used in the management of hydatidiform mole and persistent trophoblastic disease (PTD). Studies on hyperglycosylated human chorionic gonadotropin (invasive trophoblast antigen, ITA) in PTD are limited. In serum samples taken before evacuation of molar pregnancies we measured the concentrations of free hCG beta-subunit (free hCGbeta), "total" hCG (hCG+hCGbeta) and ITA, and determined whether ITA, the two other hCG analytes, or the calculated ratios of hCGbeta/hCG+hCGbeta, hCGbeta/ITA and hCG+hCGbeta/ITA could predict the later development of PTD. DESIGN: A retrospective study based on blood specimens collected in the Dutch Central Registry for Hydatidiform Moles. The study group comprised 97 patients with hydatidiform moles who did not develop PTD after mole evacuation and 33 patients who did develop PTD. Methods: Serum samples from 130 patients with hydatidiform mole with or without PTD were assayed using specific (radio)immunoassays for free hCGbeta, total hCG, and ITA. From these analytes we also calculated the ratios hCGbeta/hCG+hCGbeta, hCGbeta/ITA, and hCG+hCGbeta/ITA. To predict the development of PTD from these analytes and parameters we performed receiver-operating characteristic (ROC) curve analysis, resulting in areas under the curve (AUCs) that represented the diagnostic accuracy which was rated in a range from excellent (AUC >0.9 or <0.1) to poor (AUC 0.4-0.6). Results: The diagnostic accuracy of ITA was moderate (0.618) and not different from that of free hCGbeta (0.610) and hCG+hCGbeta (0.622). CONCLUSIONS: ITA as well as the other analytes and parameters in serum taken prior to evacuation from patients with molar pregnancies cannot be used to predict the subsequent development of persistent trophoblastic disease. 相似文献
27.
Picault N Cazalé AC Beyly A Cuiné S Carrier P Luu DT Forestier C Peltier G 《Biochimie》2006,88(11):1743-1750
The enzymatically synthesized thiol peptide phytochelatin (PC) plays a central role in heavy metal tolerance and detoxification in plants. In response to heavy metal exposure, the constitutively expressed phytochelatin synthase enzyme (PCS) is activated leading to synthesis of PCs in the cytosol. Recent attempts to increase plant metal accumulation and tolerance reported that PCS over-expression in transgenic plants paradoxically induced cadmium hypersensitivity. In the present paper, we investigate the possibility of synthesizing PCs in plastids by over-expressing a plastid targeted phytochelatin synthase (PCS). Plastids represent a relatively important cellular volume and offer the advantage of containing glutathione, the precursor of PC synthesis. Using a constitutive CaMV 35S promoter and a RbcS transit peptide, we successfully addressed AtPCS1 to chloroplasts, significant PCS activity being measured in this compartment in two independent transgenic lines. A substantial increase in the PC content and a decrease in the glutathione pool were observed in response to cadmium exposure, when compared to wild-type plants. While over-expressing AtPCS1 in the cytosol importantly decreased cadmium tolerance, both cadmium tolerance and accumulation of plants expressing plastidial AtPCS1 were not significantly affected compared to wild-type. Interestingly, targeting AtPCS1 to chloroplasts induced a marked sensitivity to arsenic while plants over-expressing AtPCS1 in the cytoplasm were more tolerant to this metalloid. These results are discussed in relation to heavy metal trafficking pathways in higher plants and to the interest of using plastid expression of PCS for biotechnological applications. 相似文献
28.
Qizhi Fang Pamela Y. Mok Anila E. Thomas Daniel J. Haddad Shereen A. Saini Brian T. Clifford Neel K. Kapasi Olivia M. Danforth Minako Usui Weisheng Ye Emmy Luu Rikki Sharma Maya J. Bartel Jeremy A. Pathmanabhan Andrew A. S. Ang Richard E. Sievers Randall J. Lee Matthew L. Springer 《PloS one》2013,8(4)
Pleiotrophin (PTN) is a growth factor with both pro-angiogenic and limited pro-tumorigenic activity. We evaluated the potential for PTN to be used for safe angiogenic gene therapy using the full length gene and a truncated gene variant lacking the domain implicated in tumorigenesis. Mouse myoblasts were transduced to express full length or truncated PTN (PTN or T-PTN), along with a LacZ reporter gene, and injected into mouse limb muscle and myocardium. In cultured myoblasts, PTN was expressed and secreted via the Golgi apparatus, but T-PTN was not properly secreted. Nonetheless, no evidence of uncontrolled growth was observed in cells expressing either form of PTN. PTN gene delivery to myocardium, and non-ischemic skeletal muscle, did not result in a detectable change in vascularity or function. In ischemic hindlimb at 14 days post-implantation, intramuscular injection with PTN-expressing myoblasts led to a significant increase in skin perfusion and muscle arteriole density. We conclude that (1) delivery of the full length PTN gene to muscle can be accomplished without tumorigenesis, (2) the truncated PTN gene may be difficult to use in a gene therapy context due to inefficient secretion, (3) PTN gene delivery leads to functional benefit in the mouse acute ischemic hindlimb model. 相似文献
29.
Dieu-Hien Truong Hoang Chinh Nguyen Julien Bauwens Gabriel Mazzucchelli Georges Lognay Frédéric Francis 《Journal of Plant Interactions》2018,13(1):30-36
The interactions between Arabidopsis thaliana and Plutella xylostella have been considered as a model system to unravel the responses of plants to herbivorous insects. Here, we use a 2-DE proteome approach to detect protein expression changes in the leaves of Arabidopsis plants exposed to P. xylostella larval infestation at 27°C within 8?h. Approximately 450 protein spots were reproducibly detected on gels. Of these, comparing healthy and infested leaves, we identified 18 differentially expressed protein spots. Thirteen proteins were successfully identified by MALDI-TOF/MS and LC-ESI-MS/MS. Functional classification analysis indicated that the differentially identified proteins were associated with amino acid, carbohydrate, energy, lipid metabolism, and photosynthesis. In addition, their relative abundances were assessed according to larval pest feeding on Arabidopsis leaves. These data provide valuable new insights for further works in plant-biotic and environmental stress interaction. 相似文献