Molecular and allergenic characterization of recombinant tropomyosin from mud crab Scylla olivacea

Molecular Biology Reports - Tropomyosin is a major allergen in crustaceans, including mud crab species, but its molecular and allergenic properties in Scylla olivacea are not well known. Thus, this...     

Theoretical descriptions of novel triplet germylenes M<Subscript>1</Subscript>-Ge-M<Subscript>2</Subscript>-M<Subscript>3</Subscript> (M<Subscript>1</Subscript> = H,Li, Na,K; M<Subscript>2</Subscript> = Be,Mg, Ca; M<Subscript>3</Subscript> = H,F, Cl,Br)

In a quest to identify new ground-state triplet germylenes, the stabilities (singlet–triplet energy differences, ΔE_S–T) of 96 singlet (s) and triplet (t) M₁-Ge-M₂-M₃ species were compared and contrasted at the B3LYP/6–311++G**, QCISD(T)/6–311++G**, and CCSD(T)/6–311++G** levels of theory (M₁?=?H, Li, Na, K; M₂?=?Be, Mg, Ca; M₃?=?H, F, Cl, Br). Interestingly, F-substituent triplet germylenes (M₃?=?F) appear to be more stable and linear than the corresponding Cl- or Br-substituent triplet germylenes (M₃?=?Cl or Br). Triplets with M₁?=?K (i.e., the K-Ge-M₂-M₃ series) seem to be more stable than the corresponding triplets with M₁?=?H, Li, or Na. This can be attributed to the higher electropositivity of potassium. Triplet species with M₃?=?Cl behave similarly to those with M₃?=?Br. Conversely, triplets with M₃?=?H show similar stabilities and linearities to those with M₃?=?F. Singlet species of formulae K-Ge-Ca-Cl and K-Ge-Ca-Br form unexpected cyclic structures. Finally, the triplet germylenes M₁-Ge-M₂-M₃ become more stable as the electropositivities of the α-substituents (M₁ and M₂) and the electronegativity of the β-substituent (M₃) increase.     

Interactive association between RhoA transcriptional signaling inhibitor,CCG1423 and human serum albumin: Biophysical and in silico studies

Multiple spectroscopic techniques, such as fluorescence, absorption, and circular dichroism along with in silico studies were used to characterize the binding of a potent inhibitor molecule, CCG1423 to the major transport protein, human serum albumin (HSA). Fluorescence and absorption spectroscopic results confirmed CCG1423–HSA complex formation. A strong binding affinity stabilized the CCG1423–HSA complex, as evident from the values of the binding constant (K_a = 1.35 × 10⁶–5.43 × 10⁵ M^?1). The K_SV values for CCG1423–HSA system were inversely correlated with temperature, suggesting the involvement of static quenching mechanism. Thermodynamic data anticipated that CCG1423–HSA complexation was mainly driven by hydrophobic and van der Waals forces as well as hydrogen bonds. In silico analysis also supported these results. Three-dimensional fluorescence and circular dichroism spectral analysis suggested microenvironmental perturbations around protein fluorophores and structural (secondary and tertiary) changes in the protein upon CCG1423 binding. CCG1423 binding to HSA also showed some protection against thermal denaturation. Site-specific marker-induced displacement results revealed CCG1423 binding to Sudlow’s site I of HSA, which was also confirmed by the computational results. A few common ions were also found to interfere with the CCG1423–HSA interaction.     

Large-scale de novo transcriptome analysis reveals specific gene expression and novel simple sequence repeats markers in salinized roots of the euhalophyte <Emphasis Type="Italic">Salicornia europaea</Emphasis>

Glycophytic plants suffer from severe stress and injury when roots are exposed to high salinity in the rhizosphere. In contrast, the euhalophyte Salicornia europaea grows well at 200 mM NaCl and can withstand up to 1000 mM NaCl in the root zone. Analysis of gene expression profiles and the underlying molecular mechanisms responsible for this tolerance have been largely overlooked. Using the Illumina sequencing platform and the short-reads assembly programme Trinity, we generated a total of 40 and 39 million clean reads and further 140,086 and 122,728 unigenes from the 200 mM NaCl and 0 mM NaCl treated tissues of S. europaea roots, respectively. All unigenes in this study were functionally annotated within context of the COG, GO and KEGG pathways. Unigene functional annotation analysis allowed us to identify hundreds of ion transporters related to homeostasis and osmotic adaptation as well as a variety of proteins related to cation, amino acid, lipid and sugar transport. We found significant enrichment in response to stress including the functional categories of “antioxidant activity”, “catalytic activity” and “response to stimuli”. These findings represent for a useful resource for the scientific community working on salt tolerance mechanisms. Conversely, a total of 8639 EST-SSRs from 131,594 unigenes were identified and 4539 non-redundant SSRs primers pairs were developed. These data provide a good foundation for future studies on molecular adaptation mechanisms of euhalophytes roots under saline environments and will likely facilitate the identification of critical salt tolerance traits to be transferred in economically important crops.     

Effects of irradiance and spectral quality on seedling development of two Southeast Asian Hopea species

 Seedling developmental responses to understory shade combine the effects of reductions in irradiance and changes in spectral quality. We studied the seedling development of two Southeast Asian dipterocarp trees in response to differences in irradiance (photosynthetic photon flux density, PPFD) and spectral quality (red to far-red ratio, R:FR). The two species, Hopea helferei and H. odorata, are taxonomically closely related but differ in their ecological requirements; H. helferei is more drought-tolerant and typically grows in more open habitats. Seedlings were grown in six different replicated shadehouse treatments varying in percentage of solar PPFD and R:FR. The two species differed in the influence of light variables on most seedling characters, particularly for final height, internode distance, branch/trunk internodes, stem length/mass, leaf area/stem length, petiole length, and growth/mol of photons received. Most of the characters in both taxa were primarily influenced by PPFD, but spectral quality also influenced some characters – more so for H. odorata. The latter species grew more rapidly, particularly in the low PPFD treatments, and its leaves were capable of higher photosynthesis rates. However, growth in H. helferei was not reduced in direct sunlight. The growth of this taxon may be constrained by adaptations, particularly in leaves, for drought tolerance. Received: 14 April 1996 / Accepted: 8 October 1996     

Biochemical studies of membrane bound Plasmodium falciparum mitochondrial L-malate:quinone oxidoreductase,a potential drug target

Plasmodium falciparum is an apicomplexan parasite that causes the most severe malaria in humans. Due to a lack of effective vaccines and emerging of drug resistance parasites, development of drugs with novel mechanisms of action and few side effects are imperative. To this end, ideal drug targets are those essential to parasite viability as well as absent in their mammalian hosts. The mitochondrial electron transport chain (ETC) of P. falciparum is one source of such potential targets because enzymes, such as L-malate:quinone oxidoreductase (PfMQO), in this pathway are absent humans. PfMQO catalyzes the oxidation of L-malate to oxaloacetate and the simultaneous reduction of ubiquinone to ubiquinol. It is a membrane protein, involved in three pathways (ETC, the tricarboxylic acid cycle and the fumarate cycle) and has been shown to be essential for parasite survival, at least, in the intra-erythrocytic asexual stage. These findings indicate that PfMQO would be a valuable drug target for development of antimalarial with novel mechanism of action. Up to this point in time, difficulty in producing active recombinant mitochondrial MQO has hampered biochemical characterization and targeted drug discovery with MQO. Here we report for the first time recombinant PfMQO overexpressed in bacterial membrane and the first biochemical study. Furthermore, about 113 compounds, consisting of ubiquinone binding site inhibitors and antiparasitic agents, were screened resulting in the discovery of ferulenol as a potent PfMQO inhibitor. Finally, ferulenol was shown to inhibit parasite growth and showed strong synergism in combination with atovaquone, a well-described anti-malarial and bc₁ complex inhibitor.