Biomolecular Tools Research Articles

(Invited) Engineering Polypeptides for Controlled Assembly of Ionomer Thin Films

Increasing evidence suggests that control of ionomer thin film structures on metal surfaces is pivotal for efficient performance in electrochemical devices such as fuel cells and electrolyzers. Unfortunately, the assembly of these thin film structures is difficult to control using conventional methods and ideal arrangements remain unknown. Engineered polypeptides have emerged as powerful biomolecular tools in electrode assembly because binding sites and polypeptide structures can be easily modulated by changing the amino acid sequence. However, no studies have been conducted showing polypeptides can be engineered to interact with ionomers, attach them to metal surfaces, and control their arrangement. Our lab has recently developed this technology, using an elastin-like polypeptide to bind to metals, and bind to acidic and basic ionomer via ionic interactions. We use a quartz crystal microbalance with dissipation to provide detailed information about the loading, thickness, and binding behavior of the polypeptide and ionomer layers. We also use atomic force microscopy and grazing-incidence small-angle X-ray scattering to understand the impact of the biomolecules on ionomer phase separation. Finally, we have begun to analyze the performance (ionic conductivity) of the assembled films using interdigitated electrodes and electrochemical impedance spectroscopy. Through these techniques, we show that 1) our biomolecular system is highly flexible, easily adapting to different materials, 2) the polypeptide sequence can dictate ionomer phase separated structures, and 3) this system can be used to improve the performance of ionomer thin films and gain structure-function understanding. Generally, our results demonstrate that engineered polypeptides are promising tools for ionomer control in electrode engineering.

New salmonid hosts for Tenacibaculum species: Expansion of tenacibaculosis in Chilean aquaculture.

The success and sustainability of Chilean aquaculture largely depends on the control of endemic and emerging pathogens, including several species of the genus Tenacibaculum. Tenacibaculum dicentrarchi and "Tenacibaculum finnmarkense" have been detected and confirmed in Chilean Atlantic salmon (Salmo salar). However, no outbreaks of tenacibaculosis in rainbow trout (Oncorhynchus mykiss) or coho salmon (Oncorhynchus kisutch) have been reported, either in Chile or globally. The aims of this study were to determine whether the mortalities recorded for rainbow trout and coho salmon from five marine fish farms located in the Los Lagos, Aysén, and Magallanes Regions could be caused by Tenacibaculum spp. The diseased fish exhibited cutaneous haemorrhages, tail and peduncle rots, and damage on the mouth and tongue. Microbiological analysis of infected external tissues yielded 13 bacterial isolates. The isolates were identified as members of the genus Tenacibaculum through biochemical analysis (e.g. Gram-stain negative, straight rods, filamentous cells and motile by gliding), but differences existed in biochemical results, making species-level identification through biomolecular tools essential. The 16S rRNA analysis found that the majority of isolates were more closely related to "T. finnmarkense" than T. dicentrarchi, while the phylogenetic trees resulting from multilocus sequence data recovered the four main clades (clades I to IV) identified by Olsen et al. (2017, Veterinary Microbiology, 205, 39). This is the first documented occurrence of clinical tenacibaculosis in farmed rainbow trout and coho salmon globally, and it extends the known host distribution of this pathogen in Chile. Moreover, we confirm the presence of Tenacibaculum species in the Chilean Patagonia. These findings highlight the importance of establishing preventative measures to minimize the spread of this disease within the Chilean marine aquaculture industry, as well as the need for monitoring initiatives worldwide in these farmed fish species.

Development of a Monoclonal Antibody Specific to the IgM Heavy Chain of Bighead Catfish (Clarias macrocephalus): A Biomolecular Tool for the Detection and Quantification of IgM Molecules and IgM+ Cells in Clarias Catfish.

Catfish is a commonly-cultivated freshwater fish in Thailand and many Southeast Asian countries. The molecular data obtained for the IgM heavy chain (IgMH) of catfish have been useful for distinguishing monoclonal antibodies (mAbs). A mAb specific to Cμ1 of the IgMH of catfish (IgMHCμ1 mAb) was developed in a rabbit model using sequence information from bighead catfish (Clarias macrocephalus). The IgMHCμ1 mAb strongly recognized the IgM heavy chain of the tested catfish, namely, bighead catfish, African catfish (Clarias gariepinus) and their hybrid (C. macrocephalus × C. gariepinus), in immunological Western blot analysis and competitive ELISAs. Additionally, the IgMHCμ1 mAb successfully recognized IgM+ cells by detecting IgM molecules in both secreted and membrane-bound forms in peripheral blood leukocytes (PBLs). The IgMHCμ1 mAb was further used to quantify the percentage of IgM+ cells among PBLs through flow cytophotometry. The IgM+ cell percentages of healthy bighead catfish, African catfish and their hybrid were 38.0–39.9%, 45.6–53.2%, and 58.7–60.0%, respectively. Furthermore, the IgMHCμ1 mAb showed no cross-reactivity with the IgM of zebrafish. These findings suggest that this mAb can be used as an immunological tool for monitoring the health, immune status, and immune development of cultivated Clarias catfish.

Facultative methanotrophs are abundant at terrestrial natural gas seeps

BackgroundNatural gas contains methane and the gaseous alkanes ethane, propane and butane, which collectively influence atmospheric chemistry and cause global warming. Methane-oxidising bacteria, methanotrophs, are crucial in mitigating emissions of methane as they oxidise most of the methane produced in soils and the subsurface before it reaches the atmosphere. Methanotrophs are usually obligate, i.e. grow only on methane and not on longer chain alkanes. Bacteria that grow on the other gaseous alkanes in natural gas such as propane have also been characterised, but they do not grow on methane. Recently, it was shown that the facultative methanotroph Methylocella silvestris grew on ethane and propane, other components of natural gas, in addition to methane. Therefore, we hypothesised that Methylocella may be prevalent at natural gas seeps and might play a major role in consuming all components of this potent greenhouse gas mixture before it is released to the atmosphere.ResultsEnvironments known to be exposed to biogenic methane emissions or thermogenic natural gas seeps were surveyed for methanotrophs. 16S rRNA gene amplicon sequencing revealed that Methylocella were the most abundant methanotrophs in natural gas seep environments. New Methylocella-specific molecular tools targeting mmoX (encoding the soluble methane monooxygenase) by PCR and Illumina amplicon sequencing were designed and used to investigate various sites. Functional gene-based assays confirmed that Methylocella were present in all of the natural gas seep sites tested here. This might be due to its ability to use methane and other short chain alkane components of natural gas. We also observed the abundance of Methylocella in other environments exposed to biogenic methane, suggesting that Methylocella has been overlooked in the past as previous ecological studies of methanotrophs often used pmoA (encoding the alpha subunit of particulate methane monooxygenase) as a marker gene.ConclusionNew biomolecular tools designed in this study have expanded our ability to detect, and our knowledge of the environmental distribution of Methylocella, a unique facultative methanotroph. This study has revealed that Methylocella are particularly abundant at natural gas seeps and may play a significant role in biogeochemical cycling of gaseous hydrocarbons.

Biomolecular Ultrasound and Sonogenetics.

Visualizing and modulating molecular and cellular processes occurring deep within living organisms is fundamental to our study of basic biology and disease. Currently, the most sophisticated tools available to dynamically monitor and control cellular events rely on light-responsive proteins, which are difficult to use outside of optically transparent model systems, cultured cells, or surgically accessed regions owing to strong scattering of light by biological tissue. In contrast, ultrasound is a widely used medical imaging and therapeutic modality that enables the observation and perturbation of internal anatomy and physiology but has historically had limited ability to monitor and control specific cellular processes. Recent advances are beginning to address this limitation through the development of biomolecular tools that allow ultrasound to connect directly to cellular functions such as gene expression. Driven by the discovery and engineering of new contrast agents, reporter genes, and bioswitches, the nascent field of biomolecular ultrasound carries a wave of exciting opportunities.

New biomolecular tools for aerobiological monitoring: Identification of major allergenic Poaceae species through fast real-time PCR.

Grasses (Poaceae) are very common plants, which are widespread in all environments and urban areas. Despite their economical importance, they can represent a problem to humans due to their abundant production of allergenic pollen. Detailed information about the pollen season for these species is needed in order to plan adequate therapies and to warn allergic people about the risks they take in certain areas at certain moments. Moreover, precise identification of the causative species and their allergens is necessary when the patient is treated with allergen‐specific immunotherapy. The intrafamily morphological similarity of grass pollen grains makes it impossible to distinguish which particular species is present in the atmosphere at a given moment. This study aimed at developing new biomolecular tools to analyze aerobiological samples and identifying major allergenic Poaceae taxa at subfamily or species level, exploiting fast real‐time PCR. Protocols were tested for DNA extraction from pollen sampled with volumetric and gravimetric methods. A fragment of the matK plastidial gene was amplified and sequenced in Poaceae species known to have high allergological impact. Species‐ and subfamily‐specific primer–probe systems were designed and tested in fast real‐time PCRs to evaluate the presence of these taxa in aerobiological pollen samples. Species‐specific systems were obtained for four of five studied species. A primer–probe set was also proposed for the detection of Pooideae (a grass subfamily that includes also major cereal grains) in aerobiological samples, as this subfamily includes species carrying both grass allergens from groups 1 and 5. These, among the 11 groups in which grass pollen allergens are classified, are considered responsible for the most frequent and severe symptoms.

Fabrication of Protein Microparticles and Microcapsules with Biomolecular Tools

Abstract Microparticles have attracted much attention for medical, analytical and biological applications. Calcium carbonate (CaCO3) templating method with the advantages of having narrow size distribution, controlled morphology and good biocompatibility that has been widely used for the synthesis of various protein-based microparticles. Despite CaCO3 template is biocompatible, most of the conventional methods to create stable protein microparticles are mainly driven by chemical crosslink reagents which may induce potential harmful effect and remains undesirable especially for biomedical or clinical applications. In this article, we demonstrate the fabrication of protein microparticles and microcapsules with an innovative method using biomolecular tools such as enzymes and affinity molecules to trigger the assembling of protein molecules within a porous CaCO3 template followed by a template removal step. We demonstrated the enzyme-assisted fabrication of collagen microparticles triggered by transglutaminase, as well as the affinity-assisted fabrication of BSA-biotin avidin microcapsules triggered by biotin-avidin affinity interaction, respectively. Based on the different protein assemble mechanisms, the collagen microparticles appeared as a solid-structured particles, while the BSA-biotin avidin microcapsules appeared as hollow-structured morphology. The fabrication procedures are simple and robust that allows producing protein microparticles or microcapsules under mild conditions at physiological pH and temperature. In addition, the microparticle morphologies, protein compositions and the assemble mechanisms were studied. Our technology provides a facile approach to design and fabricate protein microparticles and microcapsules that are useful in the area of biomaterials, pharmaceuticals and analytical chemistry.

A Brief Review on the Experimental Aspects of Bojungikki-Tang in Cancer

Bojungikki-tang (BJIKT, Hochuekkito in Japanese, Bu-zhong-yi-qi-tang in Chinese) has been widely used as a traditional herbal formula in Korea, Japan, and China to improve the function of digestive systems, the quality of life and nutritional status. Currently there are numerous basic and clinical studies to find anticancer drugs from herbal medicine. Modern biomolecular tools and approaches have contributed to understand the role and mechanism of action of herbal medicine that exhibited anticancer activity. BJIKT have also gained much attention in recent years as adjuvant treatment for cancer. This review will introduce the experimental approaches to understand the pharmacological actions of BJIKT and overview the potential for cancer treatment.

Streamlined purification of fluorescently labeled Escherichia coli phosphate-binding protein (PhoS) suitable for rapid-kinetics applications

Fluorescently labeled phosphate-binding proteins can be used as biomolecular tools to measure the release of inorganic phosphate (Pi) from enzymes in real time, enabling the detailed kinetic analysis of dephosphorylating enzymes using rapid-kinetics approaches. Previously reported methods to purify fluorescently labeled phosphate-binding proteins (PhoS) from Escherichia coli are laborious, and a simplified approach is needed. Here, we report the characterization of a cytosol-localized variant (A197C) of PhoS that allows a streamlined purification for subsequent covalent conjugation with a fluorescent dye. We show that export of PhoS into the periplasmic space is not required for the fluorescence-based detection of Pi binding. Furthermore, we report the addition of a C-terminal His-tag, simplifying the purification of PhoS from the cytosol via Ni2+-affinity chromatography, yielding a fully functional fusion protein (HC PhoS A197C).We demonstrate the utility of fluorescently labeled HC PhoS A197C for rapid-kinetics applications by measuring, using stopped-flow, the Pi release kinetics from LepA/EF4 following 70S ribosome-stimulated GTP hydrolysis. Altogether, the approach developed here allows for the high-yield and simplified in-house production of a Pi detection system suitable for rapid-kinetics approaches with comparable sensitivity to the commercially available Phosphate Sensor.

Going Deeper: Biomolecular Tools for Acoustic and Magnetic Imaging and Control of Cellular Function.

Most cellular phenomena of interest to mammalian biology occur within the context of living tissues and organisms. However, today's most advanced tools for observing and manipulating cellular function, based on fluorescent or light-controlled proteins, work best in cultured cells, transparent model species, or small, surgically accessed anatomical regions. Their reach into deep tissues and larger animals is limited by photon scattering. To overcome this limitation, we must design biochemical tools that interface with more penetrant forms of energy. For example, sound waves and magnetic fields easily permeate most biological tissues, allowing the formation of images and delivery of energy for actuation. These capabilities are widely used in clinical techniques such as diagnostic ultrasound, magnetic resonance imaging, focused ultrasound ablation, and magnetic particle hyperthermia. Each of these modalities offers spatial and temporal precision that could be used to study a multitude of cellular processes in vivo. However, connecting these techniques to cellular functions such as gene expression, proliferation, migration, and signaling requires the development of new biochemical tools that can interact with sound waves and magnetic fields as optogenetic tools interact with photons. Here, we discuss the exciting challenges this poses for biomolecular engineering and provide examples of recent advances pointing the way to greater depth in in vivo cell biology.

Neuronal P2X7 Receptor: Involvement in Neuronal Physiology and Pathology.

The proposed presence of P2X7 receptor (P2X7R) in neurons has been the source of some contention. Initial studies suggested an absence of P2X7R mRNA in neurons, and the apparent nonspecificity of the antibodies used to identify P2X7R raised further doubts. However, subsequent studies using new pharmacological and biomolecular tools provided conclusive evidence supporting the existence of functional P2X7Rs in neurons. The P2X7 receptor has since been shown to play a leading role in multiple aspects of neuronal physiology, including axonal elongation and branching and neurotransmitter release. P2X7R has also been implicated in neuronal pathologies, in which it may influence neuronal survival. Together, this body of research suggests that P2X7R may constitute an important therapeutic target for a variety of neurological disorders.

Stratification of chlorinated ethenes natural attenuation in an alluvial aquifer assessed by hydrochemical and biomolecular tools

Biomolecular and hydrochemical tools were used to evaluate natural attenuation of chlorinated ethenes in a Quaternary alluvial aquifer located close to a historical source of large-scale tetrachloroethylene (PCE) contamination. Distinct stratification of redox zones was observed, despite the aquifer's small thickness (2.8 m). The uppermost zone of the target aquifer was characterised by oxygen- and nitrate-reducing conditions, with mixed iron- to sulphate-reducing conditions dominant in the lower zone, along with indications of methanogenesis. Natural attenuation of PCE was strongly influenced by redox heterogeneity, while higher levels of PCE degradation coincided with iron- to sulphate reducing conditions. Next generation sequencing of the middle and/or lower zones identified anaerobic bacteria (Firmicutes, Chloroflexi, Actinobacteria and Bacteroidetes) associated with reductive dechlorination. The relative abundance of dechlorinators (Dehalococcoides mccartyi, Dehalobacter sp.) identified by real-time PCR in soil from the lower levels supports the hypothesis that there is a significant potential for reductive dechlorination of PCE. Local conditions were insufficiently reducing for rapid complete dechlorination of PCE to harmless ethene. For reliable assessment of natural attenuation, or when designing monitoring or remedial systems, vertical stratification of key biological and hydrochemical markers should be analysed as standard, even in shallow aquifers.

Phenological analysis of grasses (Poaceae) as a support for the dissection of their pollen season in Perugia (Central Italy)

Grasses (Poaceae) pollen is a major cause for allergic diseases worldwide. Pollen monitoring in the atmosphere is of primary importance for symptoms interpretation and therapy planning. Microscopic pollen identification and counts do not allow the detection at species or genus level because of the stenopalynous nature of the family. Nevertheless, the assessment of the flowering phenology of different species would be important, because not all grass allergens are cross-reacting and allergic patients could be differentially sensitized. In this work, a phenological survey was carried out in five stations located on the urban territory of Perugia (Central Italy), from April to September 2015, recording the alternation between flowering phenophases of 19 grass species and estimating their contribution to the airborne pollen load of the area through the calculation of a Phenological Index. Moreover, pollen grains of the different species were collected and observed, confirming the impossibility to make a discrimination during microscope pollen counts. The prevailing grasses in terms of contribution to the pollen detection in the studied area resulted to be Dactylis glomerata and Lolium perenne during spring and early summer, and Cynodon dactylon during late summer. Data should be validated repeating the survey in successive years and possibly using biomolecular tools, but the obtained information could be relevant for diagnosis and treatment of grass pollen allergies.

Emerging applications of label-free optical biosensors

AbstractInnovative technical solutions to realize optical biosensors with improved performance are continuously proposed. Progress in material fabrication enables developing novel substrates with enhanced optical responses. At the same time, the increased spectrum of available biomolecular tools, ranging from highly specific receptors to engineered bioconjugated polymers, facilitates the preparation of sensing surfaces with controlled functionality. What remains often unclear is to which extent this continuous innovation provides effective breakthroughs for specific applications. In this review, we address this challenging question for the class of label-free optical biosensors, which can provide a direct signal upon molecular binding without using secondary probes. Label-free biosensors have become a consolidated approach for the characterization and screening of molecular interactions in research laboratories. However, in the last decade, several examples of other applications with high potential impact have been proposed. We review the recent advances in label-free optical biosensing technology by focusing on the potential competitive advantage provided in selected emerging applications, grouped on the basis of the target type. In particular, direct and real-time detection allows the development of simpler, compact, and rapid analytical methods for different kinds of targets, from proteins to DNA and viruses. The lack of secondary interactions facilitates the binding of small-molecule targets and minimizes the perturbation in single-molecule detection. Moreover, the intrinsic versatility of label-free sensing makes it an ideal platform to be integrated with biomolecular machinery with innovative functionality, as in case of the molecular tools provided by DNA nanotechnology.

Multivalent Aptamers: Versatile Tools for Diagnostic and Therapeutic Applications.

Nucleic acid aptamers generated through an in vitro selection are currently extensively applied as very valuable biomolecular tools thanks to their prominent advantages. Diversity of spatial structures, ease of production through chemical synthesis and a large variety of chemical modifications make aptamers convenient building blocks for the generation of multifunctional constructs. An opportunity to combine different aptamer functionalities with other molecules of interest such as reporter groups, nanoparticles, chemotherapeutic agents, siRNA or antisense oligonucleotides provides a widest range of applications of multivalent aptamers. The present review summarizes approaches to the design of multivalent aptamers, various examples of multifunctional constructs and the prospects of employing them as components of biosensors, probes for affinity capture, tools for cell research and potential therapeutic candidates.

Biotechnology and Bioengineering: Volume 113, Number 5, May, 2016

Biotechnology and BioengineeringVolume 113, Issue 5 p. 907-911 Issue Information - TOCFree Access Biotechnology and Bioengineering: Volume 113, Number 5, May, 2016 First published: 30 March 2016 https://doi.org/10.1002/bit.25759AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract Cover Legend CRISPR-Cas systems have proven to be powerful biomolecular tools in applications ranging from genome editing to targeted antimicrobials. In this issue, Luo and coworkers review the current state of these tools in bacteria and highlight opportunities for further advances. The image represents the diverse toolbox of CRISPR-based tools that can be applied to understand and engineer the bacterial world. Image credit: Amy Beisel. The cover image, by Chase Beisel et al., is based on the Review Current and future prospects for CRISPR-based tools in bacteria, DOI: 10.1002/bit.25851. Volume113, Issue5May 2016Pages 907-911 RelatedInformation

Modulation of the gut microbiota composition by rifaximin in non-constipated irritable bowel syndrome patients: a molecular approach

Rifaximin, with its low systemic absorption, may represent a treatment of choice for irritable bowel syndrome (IBS), mainly due to its ability to act on IBS pathogenesis, through the influence on gut microbiota. The aim of the present study was to assess, by biomolecular tools, the rifaximin active modulation exerted on gut microbiota of non-constipated IBS patients. Fifteen non-constipated IBS subjects were treated with 550 mg rifaximin three times a day for 14 days. Stool samples were collected before starting the treatment, at the end of it, and after a 6-week washout period. Real-time polymerase chain reaction, denaturing gradient gel electrophoresis, and next-generation sequencing were applied to all the samples to verify and quantify possible microbial fluctuations. Rifaximin treatment did not affect the overall composition of the microbiota of the treated subjects, inducing fluctuations in few bacterial groups, balanced by the replacement of homologs or complementary bacterial groups. Rifaximin appeared to influence mainly potentially detrimental bacteria, such as Clostridium, but increasing the presence of some species, such as Faecalibacterium prausnitzii. A decrease in the Firmicutes/Bacteroidetes ratio after 14 days of treatment and bacterial profiles with higher biodiversity were observed during the follow-up compared to baseline. Rifaximin treatment, although effective on IBS symptom relief and normalization of lactulose breath test, did not induce dramatic shifts in the microbiota composition of the subjects, stimulating microbial reorganization in some populations toward a more diverse composition. It was not possible to speculate on differences of fecal microbiota modification between responders vs nonresponders and to correlate the quali-/quantitative modification of upper gastrointestinal microbiota and clinical response.

Current and future prospects for CRISPR-based tools in bacteria.

CRISPR-Cas systems have rapidly transitioned from intriguing prokaryotic defense systems to powerful and versatile biomolecular tools. This article reviews how these systems have been translated into technologies to manipulate bacterial genetics, physiology, and communities. Recent applications in bacteria have centered on multiplexed genome editing, programmable gene regulation, and sequence-specific antimicrobials, while future applications can build on advances in eukaryotes, the rich natural diversity of CRISPR-Cas systems, and the untapped potential of CRISPR-based DNA acquisition. Overall, these systems have formed the basis of an ever-expanding genetic toolbox and hold tremendous potential for our future understanding and engineering of the bacterial world.

Abstract 1978: Relationship between transcription factor TWIST1 and microRNA34a in metastatic cancer cells

Abstract Background: Micro RNAs (miRNAs) are the important tools in RNA-interference (RNAi) technology, which is comparatively recent but one of the most promising bio-molecular tools for gene regulation. MiRNAs can interfere with certain genes in target specific manner, and they are being extensively investigated for cancer therapeutics. This study investigated the role of miR-34a on the expression of transcription factor TWIST1, which is involved in metastatic carcinomas. Methods: The expression of miR34a and TWIST1 was measured by quantitative polymerase chain reaction (qPCR) analysis in different cancer cell lines and breast cancer tissues. Then we have transfected the precursor and inhibitor of miR-34a into another TWIST1 rich 4T1 cancer cell, and isolated the total RNA and miRNAs for the analysis of TWIST1 expression, as well as miR-34a. Results: Initially, we have observed that miR34a is highly expressed in lower invasive MCF7 and T47D cancer cells, whereas its expression in higher invasive MDA-MB-231, MDA-MB-435 and BT-549 cancer cells is low. Oppositely, TWIST1 expression is relatively lower in MCF7 and T47D cells, but higher in MDA-MB-231, MDA-MB-435 and BT-549 cells. This inverse relationship indicated that TWIST1 might be a target of miR-34a. Interestingly transfection of miR34a precursor inhibited TWIST1 expression in 4T1 cancer cells. Conclusions: This study reports that miR-34a has reverse correlation with the high TWIST1 expression in metastatic breast cancer. Regulation of TWIST1 by miR-34a might be a potential tool in cancer diagnostics and therapeutics, especially for the treatment of metastatic cancers. Funding support: This work was supported in part by the NSFC (81172049), the Science and Technology Innovation Team of Colleges and Universities of Sichuan Province (13TD0032), the Applied Basic Research Program of Science and Technology Department of Sichuan Province (14JC0797,)and Luzhou City Special Foundation (2013LZLY-J10).Corresponding author email:fujunjiang@hotmail.com Citation Format: Md. Asaduzzaman Khan, Mousumi Tania, Chunli Wei, Junjiang Fu. Relationship between transcription factor TWIST1 and microRNA34a in metastatic cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1978. doi:10.1158/1538-7445.AM2015-1978

Parameters influencing the photo-induced electron transfer from tryptophan-containing peptides to a Ru(II) complex: a systematic study.

Ruthenium(II) polyazaaromatic complexes have gained interest in recent decades as biomolecular tools, especially in the development of new phototherapeutic agents. These light emissive Ru complexes based on π-deficient ligands were first designed to allow a photo-induced electron transfer (PET) with the guanine base in DNA since their (3)MLCT state is highly photo-oxidizing. Later the field of research was extended to proteins with the highlighting of a PET process with the tryptophan residue. This paper reports the kinetics of the luminescence quenching of [Ru(TAP)2phen](2+) by several selected peptide sequences containing at least one tryptophan residue. By using a peptide library we highlight the important parameters influencing the kinetics of the photo-electron transfer process, such as the net electrostatic charge and the number of tryptophan residues. The best peptide candidates were selected to study the formation of photo-products by MALDI-ToF mass spectrometry. A high photoreactivity of the [Ru(TAP)2phen](2+) complex was observed and multiple photoadducts were characterized, among them inter-peptidic adducts as well as intra-peptidic adducts.