Surface Chirality of Gly‐Pro Dipeptide Adsorbed on a Cu(110) Surface

The adsorption of chiral Gly‐Pro dipeptide on Cu(110) has been characterized by combining in situ polarization modulation infrared reflection absorption spectroscopy (PM‐RAIRS) and X‐ray photoelectron spectroscopy (XPS). The chemical state of the dipeptide, and its anchoring points and adsorption geometry, were determined at various coverage values. Gly‐Pro molecules are present on Cu(110) in their anionic form (NH₂/COO⁻) and adsorb under a 3‐point binding via both oxygen atoms of the carboxylate group and via the nitrogen atom of the amine group. Low‐energy electron diffraction (LEED) and scanning tunneling microscopy (STM) have shown the presence of an extended 2D chiral array, sustained via intermolecular H‐bonds interactions. Furthermore, due to the particular shape of the molecule, only one homochiral domain is formed, creating thus a truly chiral surface. Chirality 27:411–416, 2015. © 2015 Wiley Periodicals, Inc.     

Site-saturation mutagenesis of proline 176 in Cyclodextrin Glucosyltransferase from Bacillus sp. Y112 effects product specificity and enzymatic properties

Based on the analysis of amino acid sequence and simulated structure, saturation mutagenesis was performed to explore the role of the site p176 of cyclodextrin glucosytransferase (CGTase) from Bacillus sp. Y112. Compared to the wild-type, mutant P176G showed 10.4 % improvement in conversion from starch to cyclodextrins (CDs), whose β-CD yield increased by 6% and α-CD yield decreased by 8%. Mutants P176L and P176I were increased by 7.9 % and 9.4 % on CDs production, indicating replacement of hydrophobic amino acids significantly improved in cyclization activity. Kinetics studies indicated the substrate affinity of P176G and P176K were increase by 13 % and 14 %, and the catalytic efficiency of P176K was increase by 14 %. In addition, the optimal temperature of mutants transformed from 50℃ to 40℃ and the optimal pH shifted from 10.0 to 8.0. These results indicate that the site P176 plays a critical role in catalytic activity, product specificity and enzymatic properties of CGTase.     

Molecular & biochemical analysis of Pro12Ala variant of PPAR-γ2 gene in type 2 diabetes mellitus

Diabetes has emerged as a major threat to human life globally. Genomic studies have found a significant link between the Pro12Ala polymorphism of the PPAR-γ2 gene with incidence as well as occurrence of the risk of metabolic syndrome. The present study was aimed at assessing the PPAR-γ2 variant in an Asian Indian cohort of type 2 diabetes patients and its correlation with metabolic parameters. The present case-control study involved 100 type 2 diabetic patients and 100 asymptomatic healthy volunteers enrolled in random. Assessment of demographic factors and biochemical parameters were done for all enrolled. In addition, genotyping for the Pro12Ala (CCA to GCA) polymorphism was done by polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP) technology. The genotyping study detected the frequency of the CC genotype (Pro12Pro) to be higher in frequency in comparison to the heterozygous CG genotype in both, cases and controls. The homozygous GG genotype (Ala12Ala) was not detected in any of the cases or controls assessed. Biochemical analysis of the levels of malondialdehyde (MDA) detected a significant increase (p < 0.0001). Additionally, increase in levels of fasting and postprandial glucose, total cholesterol, triglycerides, and parameters of the liver and renal function tests were detected. This study detected the PPAR-γ2 to be a significant biomarker for type 2 diabetes mellitus.     

In Vitro Selection of Single‐Stranded DNA Aptamers that Bind Human Pro‐Urokinase

Single‐chain pro‐urokinase is an inactive proenzyme form of human urokinase (urinary plasminogen activator) with a Mr of 50,000 which is converted to the active two‐chain form by catalytic amounts of plasmin. It is used for thrombolytic therapy of acute myocardial infarction and acute ischemic stroke. We have isolated single‐stranded DNA molecules with significantly increased binding affinity for human pro‐urokinase by SELEX (systematic evolution of ligands by exponential enrichment) procedure from a pool of 10¹⁵ molecules containing 24 randomized positions which are flanked by defined regions. ssDNA from this library was hybridized with helper «fixture», thus allowing the central random chain to fold into complex three‐dimentional shapes. Sequencing data from pro‐urokinase aptamers obtained after 12 selection cycles displayed a highly conserved 12–14 base region.     

Evolutionary patterns of the mitochondrial genome in the Moorish gecko, Tarentola mauritanica

A previous study on the evolutionary patterns of Tarentola mauritanica demonstrated that low levels of mitochondrial diversity observed in the European populations relative to nuclear markers were consistent with a selective sweep hypothesis. In order to unravel the mitochondrial evolutionary history in this European population and two other lineages of T. mauritanica (Iberian and North African clades), variation within 22 nearly complete mitogenomes was analyzed. Surprisingly, each clade seems to have a distinct evolutionary history; with both the European and Iberian clades presenting a decrease of polymorphism, which in the former is consistent with departure from neutrality of the mtDNA (positive or background selection), but in the latter seems to be the result of a bottleneck after a population expansion. The pattern exhibited by the North African clade seems to be a consequence of adaptation to certain mtDNA variants by positive selection.     

Increased expression of (pro)renin receptor in aldosterone-producing adenomas

(Pro)renin receptor ((P)RR) is a specific receptor for renin and prorenin. The aim of the present study is to clarify expression and possible pathophysiological roles of (P)RR in aldosterone-producing adenomas (APAs) and other adrenal tumors. Expression of (P)RR was studied by immunocytochemistry, western blot analysis and real-time RT-PCR in adrenal tumor tissues obtained at surgery. Immunocytochemistry showed that (P)RR was expressed in normal adrenal glands and tumor tissues of adrenocortical tumors including APAs. In the normal adrenal glands, positive (P)RR immunostaining was observed in both adrenal cortex and medulla, with higher (P)RR immunostaining observed in zona glomerulosa and zona reticularis. Positive (P)RR immunostaining was also observed in the adrenocortical tumors, with elevated (P)RR immunostaining found in APAs, particularly in compact cells. By contrast, no apparent (P)RR immunostaining was observed in pheochromocytomas. Western blot analysis showed a band of (P)RR protein in normal adrenal glands and adrenocortical tumors at the position of 35 kDa. The relative expression levels of (P)RR protein were higher in tumor tissues of APAs than in attached non-neoplastic adrenal tissues of APAs. Real-time RT-PCR showed that expression levels of (P)RR mRNA were significantly increased in tumor tissues of APAs compared with other adrenal tumor tissues and attached non-neoplastic adrenal tissues of APAs. The present study has shown for the first time that expression of (P)RR is elevated in tumor tissues of APAs, raising the possibility that (P)RR may play pathophysiological roles in APAs, such as aldosterone secretion and cell proliferation.     

Cyanobacterial bioactive metabolites—A review of their chemistry and biology

Cyanobacterial blooms occur when algal densities exceed baseline population concentrations. Cyanobacteria can produce a large number of secondary metabolites. Odorous metabolites affect the smell and flavor of aquatic animals, whereas bioactive metabolites cause a range of lethal and sub-lethal effects in plants, invertebrates, and vertebrates, including humans. Herein, the bioactivity, chemistry, origin, and biosynthesis of these cyanobacterial secondary metabolites were reviewed. With recent revision of cyanobacterial taxonomy by Anagnostidis and Komárek as part of the Süβwasserflora von Mitteleuropa volumes 19(1–3), names of many cyanobacteria that produce bioactive compounds have changed, thereby confusing readers. The original and new nomenclature are included in this review to clarify the origins of cyanobacterial bioactive compounds.Due to structural similarity, the 157 known bioactive classes produced by cyanobacteria have been condensed to 55 classes. This review will provide a basis for more formal procedures to adopt a logical naming system. This review is needed for efficient management of water resources to understand, identify, and manage cyanobacterial harmful algal bloom impacts.     

Steric and electronic interactions controlling the cis/trans isomer equilibrium at X‐pro tertiary amide motifs in solution

A systematic understanding of the noncovalent interactions that influence the structures of the cis conformers and the equilibrium between the cis and the trans conformers, of the X‐Pro tertiary amide motifs, is presented based on analyses of ¹H‐, ¹³C‐NMR and FTIR absorption spectra of two sets of homologous peptides, X‐Pro‐Aib‐OMe and X‐Pro‐NH‐Me (where X is acetyl, propionyl, isobutyryl and pivaloyl), in solvents of varying polarities. First, this work shows that the cis conformers of any X‐Pro tertiary amide motif, including Piv‐Pro, are accessible in the new motifs X‐Pro‐Aib‐OMe, in solution. These conformers are uniquely observable by FTIR spectroscopy at ambient temperatures and by NMR spectroscopy from temperatures as high as 273 K. This is made possible by the persistent presence of n_i‐1→π_i* interactions at Aib, which also influence the disappearance of steric effects at these cis X‐Pro rotamers. Second, contrary to conventional understanding, the energy contribution of steric effects to the cis/trans equilibrium at the X‐Pro motifs is found to be nonvariant (0.54 ± 0.02 kcal/mol) with increase in steric bulk on the X group. Third, the current studies provide direct evidence for the weak intramolecular interactions namely the n_i‐1→π_i*, the N_Pro???H_i+1 (C₅a), and the C₇ hydrogen bond that operate and influence the structures, stabilities, and dynamics between different conformational states of X‐Pro tertiary amide motifs. NMR and IR spectral data suggest that the cis conformers of X‐Pro motifs are ensembles of short‐lived rotamers about the C′_X–N_Pro bond. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 66–77, 2014.     

Who Is the King? The α‐Hydroxy‐β‐oxo‐α,β‐enone Moiety or the Catechol B Ring: Relationship between the Structure of Quercetin Derivatives and Their Pro‐Oxidative Abilities

Quercetin and other flavonoids have been reported to exhibit both antioxidant and pro‐oxidant properties. Most studies about the pro‐oxidative ability were conducted in the presence of metal ions, and the essential functional moiety of quercetin responsible for the pro‐oxidative effect is still unclear. In this study, we evaluated the pro‐oxidative abilities in the absence of metal ions of two quercetin derivatives, i.e., quercetin‐3′‐O‐β‐D ‐glucoside ( 1 ) and quercetin‐3‐O‐β‐D ‐glucoside ( 2 ), by assessing DNA cleavage and HO^.‐radical production. The binding mode between these compounds and DNA was studied by fluorescence and viscometric titrations. The results showed that 1 can efficiently induce oxidative damage to plasmid DNA, while 2 shows poor activity. Both 1 and 2 bind to DNA via groove‐binding. These results proved that the α‐hydroxy‐β‐oxo‐α,β‐enone moiety contributes to the pro‐oxidative activity of quercetin.     

A New Quinolone and Other Constituents from the Fruits of Tetradium ruticarpum: Effects on Neutrophil Pro‐Inflammatory Responses

The fruit of Tetradium ruticarpum is widely used in healthcare products for the improvement of blood circulation, headache, abdominal pain, amenorrhea, chill limbs, migraine, and nausea. A new quinolone, 2‐[(6Z,9Z)‐pentadeca‐6,9‐dienyl]quinolin‐4(1H)‐one ( 1 ), has been isolated from the fruits of T. ruticarpum, together with eleven known compounds. The structure of the new compound was determined by NMR and MS analyses. Rutaecarpine ( 4 ), evodiamine ( 5 ), and skimmianine ( 7 ) exhibited inhibition (IC₅₀≤20.9 μM ) of O$\rm{{_{2}^{{^\cdot} -}}}$ generation by human neutrophils in response to N‐formyl‐L ‐methionyl‐L ‐leucyl‐L ‐phenylalanine/cytochalasin B (fMLP/CB). In addition, 1 , evocarpine ( 2 ), 4, 7 , and evodol ( 8 ) inhibited fMLP/CB‐induced elastase release with IC₅₀ values ≤14.4 μM .