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61.
Shumaila Afrin Yusra Rahman Mustafa Alhaji Isa Shahbaz Ahmed 《Journal of biomolecular structure & dynamics》2020,38(10):3046-3058
AbstractThe binding characteristic of anti-platelet drug dipyridamole has been investigated with a transport protein, serum albumin. A multi-spectroscopic approach has been employed, and the results were well supported by in silico molecular docking and simulation studies. The fluorescence quenching of serum albumin at three different temperatures revealed that the mechanism involved is static and the binding constant of the interaction was found to be of the order of 104 M?1. The reaction was found to be spontaneous and involved hydrophobic interactions. Synchronous, 3D fluorescence and CD spectroscopy indicated a change in conformation of bovine serum albumin (BSA) on interaction with DP. Using site-selective markers, the binding site of DP was found to be in subdomain IB. Molecular docking studies further corroborated these results. Molecular dynamic (MD) simulations showed lower RMSD values on interaction, suggesting the existence of a stable complex between DP and BSA. Furthermore, since β-Cyclodextrin (βCD) is used to improve the solubility of DP in ophthalmic solutions, therefore, the effect of (βCD) on the interaction of BSA and DP was also studied, and it was found that in the presence of βCD, the binding constant for BSA-DP interaction decreased. The present study is an attempt to characterize the transport of DP and to improve its bioavailability, consequently helping in dosage design to achieve optimum therapeutic levels.Communicated by Ramaswamy H. Sarma 相似文献
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Niaz Ahmad Mehboob-ur Rahman Zahid Mukhtar Yusuf Zafar Baohong Zhang 《Journal of cellular physiology》2020,235(2):666-682
Clustered regularly interspaced short palindromic repeats (CRISPR)-based genome editing, derived from prokaryotic immunity system, is rapidly emerging as an alternative platform for introducing targeted alterations in genomes. The CRISPR-based tools have been deployed for several other applications including gene expression studies, detection of mutation patterns in genomes, epigenetic regulation, chromatin imaging, etc. Unlike the traditional genetic engineering approaches, it is simple, cost-effective, and highly specific in inducing genetic variations. Despite its popularity, the technology has limitations such as off-targets, low mutagenesis efficiency, and its dependency on in-vitro regeneration protocols for the recovery of stable plant lines. Several other issues such as persisted CRISPR activity in subsequent generations, the potential for transferring to its wild type population, the risk of reversion of edited version to its original phenotype particularly in cross-pollinated plant species when released into the environment and the scarcity of validated targets have been overlooked. This article briefly highlights these undermined aspects, which may challenge the wider applications of this platform for improving crop genetics. 相似文献
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Qilu Ye Yedan Feng Yanxia Yin Frédérick Faucher Mark A. Currie Mona N. Rahman Jin Jin Shanze Li Qun Wei Zongchao Jia 《Cellular signalling》2013,25(12):2661-2667
Calcineurin is the only known calmodulin (CaM) activated protein phosphatase, which is involved in the regulation of numerous cellular and developmental processes and in calcium-dependent signal transduction. Although commonly assumed that CaM displaces the autoinhibitory domain (AID) blocking substrate access to its active site, the structural basis underlying activation remains elusive. We have created a fused ternary complex (CBA) by covalently linking three polypeptides: CaM, calcineurin regulatory B subunit (CnB) and calcineurin catalytic A subunit (CnA). CBA catalytic activity is comparable to that of fully activated native calcineurin in the presence of CaM. The crystal structure showed virtually no structural change in the active site and no evidence of CaM despite being covalently linked. The asymmetric unit contains four molecules; two parallel CBA pairs are packed in an antiparallel mode and the large cavities in crystal packing near the calcineurin active site would easily accommodate multiple positions of AID-bound CaM. Intriguingly, the conformation of the ordered segment of AID is not altered by CaM; thus, it is the disordered part of AID, which resumes a regular α-helical conformation upon binding to CaM, which is displaced by CaM for activation. We propose that the structural basis of calcineurin activation by CaM is through displacement of the disordered fragment of AID which otherwise impedes active site access. 相似文献
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Israt Jahan Yuriko Hirai Zahed Mohammad Malequr Rahman Md Anwarul Islam Hirohisa Hirai 《Primates; journal of primatology》2013,54(4):335-340
Hoolock gibbons (genus Hoolock) are a group of very endangered primate species that belong to the small ape family (family Hylobatidae). The entire population that is distributed in the northeast and southeast of Bangladesh is estimated to include only around 350 individuals. A conservation program is thus necessary as soon as possible. Genetic markers are significant tools for planning such programs. In this study, we examined chromosomal characteristics of two western hoolock gibbons that were captured in a Bangladesh forest. During chromosome analysis, we encountered two chromosome variations that were observed for the first time in the wild-born western hoolock gibbons (Hoolock hoolock). The first one was a nonhomologous centromere position in chromosome 8 that was observed in the two examined individuals. The alteration was identical in the two individuals, which were examined by G-band and DAPI-band analyses. Chromosome paint analyses revealed that the difference in the centromere position was due to a single small pericentric inversion. The second variation was a heterozygous elongation in chromosome 9. Analysis by sequential techniques of fluorescence in situ hybridization with 18S rDNA and silver nitrate staining revealed a single and an inverted tandem duplication, respectively, of the nucleolus organizer region in two individuals. These chromosome variations provide useful information for the next steps to consider the evolution and conservation of the hoolock gibbon. 相似文献
66.
The two-partner secretion (TPS) systems of Gram-negative bacteria consist of a large secreted exoprotein (TpsA) and a transporter protein (TpsB) located in the outer membrane. TpsA targets TpsB for transport across the membrane via its ∼30-kDa TPS domain located at its N terminus, and this domain is also the minimal secretory unit. Neisseria meningitidis genomes encode up to five TpsAs and two TpsBs. Sequence alignments of TPS domains suggested that these are organized into three systems, while there are two TpsBs, which raised questions on their system specificity. We show here that the TpsB2 transporter of Neisseria meningitidis is able to secrete all types of TPS domains encoded in N. meningitidis and the related species Neisseria lactamica but not domains of Haemophilus influenzae and Pseudomonas aeruginosa. In contrast, the TpsB1 transporter seemed to be specific for its cognate N. meningitidis system and did not secrete the TPS domains of other meningococcal systems. However, TpsB1 did secrete the TPS2b domain of N. lactamica, which is related to the meningococcal TPS2 domains. Apparently, the secretion depends on specific sequences within the TPS domain rather than the overall TPS domain structure. 相似文献
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Female choice can impose persistent directional selection on male sexually selected traits, yet such traits often exhibit high levels of phenotypic variation. One explanation for this paradox is that if sexually selected traits are costly, only the fittest males are able to acquire and allocate the resources required for their expression. Furthermore, because male condition is dependent on resource allocation, condition dependence in sexual traits is expected to underlie trade‐offs between reproduction and other life‐history functions. In this study we test these ideas by experimentally manipulating diet quality (carotenoid levels) and quantity in the guppy (Poecilia reticulata), a livebearing freshwater fish that is an important model for understanding relationships between pre‐ and post‐copulatory sexually selected traits. Specifically, we test for condition dependence in the expression of pre‐ and postcopulatory sexual traits (behavior, ornamentation, sperm traits) and determine whether diet manipulation mediates relationships among these traits. Consistent with prior work we found a significant effect of diet quantity on the expression of both pre‐ and postcopulatory male traits; diet‐restricted males performed fewer sexual behaviors and exhibited significant reductions in color ornamentation, sperm quality, sperm number, and sperm length than those fed ad libitum. However, contrary to our expectations, we found no significant effect of carotenoid manipulation on the expression of any of these traits, and no evidence for a trade‐off in resource allocation between pre‐ and postcopulatory episodes of sexual selection. Our results further underscore the sensitivity of behavioral, ornamental, and ejaculate traits to dietary stress, and highlight the important role of condition dependence in maintaining the high variability in male sexual traits. 相似文献