Monoamine Neurotransmitters as Substrates for Novel Tick Sulfotransferases, Homology Modeling, Molecular Docking, and Enzyme Kinetics

Blacklegged ticks (Ixodes scapularis) transmit the causative agent of Lyme disease in the Northeastern United States. Current research focuses on elucidating biochemical pathways that may be disrupted to prevent pathogen transmission, thereby preventing disease. Genome screening reported transcripts coding for two putative sulfotransferases in whole tick extracts of the nymphal and larval stages. Sulfotransferases are known to sulfonate phenolic and alcoholic receptor agonists such as 17β-estradiol, thereby inactivating the receptor ligands. We used bioinformatic approaches to predict substrates for Ixosc Sult 1 and Ixosc Sult 2 and tested the predictions with biochemical assays. Homology models of 3D protein structure were prepared, and visualization of the electrostatic surface of the ligand binding cavities showed regions of negative electrostatic charge. Molecular docking identified potential substrates including dopamine, R-octopamine and S-octopamine, which docked into Ixosc Sult 1 with favorable binding affinity and correct conformation for sulfonation. Dopamine, but not R- or S-octopamine, also docked into Ixosc Sult 2 in catalytic binding mode. The predictions were confirmed using cytosolic fractions of whole tick extracts. Dopamine was a good substrate (Km = 0.1−0.4 μM) for the native Ixodes scapularis sulfotransferases from larval and nymphal stages regardless of their fed/unfed status. Octopamine sulfonation was detected only after feeding when gene expression data suggests that Ixosc Sult 1 is present. Because dopamine is known to stimulate salivation in ticks through receptor stimulation, these results imply that the function(s) of Ixosc Sult 1 or 2 may include inactivation of the salivation signal via sulfonation of dopamine and/or octopamine

The information society of the 90's: convention for top international DP user management ; 6th Informatics Convention, Munich, October 18 - 20, 1989

SIGLEAvailable from Bibliothek des Instituts fuer Weltwirtschaft, ZBW, Duesternbrook Weg 120, D-24105 Kiel C 168372 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Evaluation of the efficiency of odor removal from recycled HDPE using a modified recycling process

A series of recent global and local policymaking processes is promoting or demanding developments in the recycling of post-consumer plastic packaging waste. After successfully clearing most hurdles in the PET bottle sector to promote a successful market launch of the recycled PET products, it is now important to take measures to meet the challenges associated with the recycling of polyolefins such as HDPE. In this respect, the need to further improve recycling technologies is currently prevalent because the quality parameters of the recycled materials do not yet meet the strict industrial requirements. In this context, apart from optical or mechanical properties, there is increasing awareness of odorous contaminants in the recycled products. Therefore, in this study, a modified HDPE recycling method was evaluated for its ability to reduce odors. For the aim of mapping and understanding the odor of recycled HDPE pellets with different residence times in a special decontamination reactor a combinatory sensory and instrumental-olfactometric approach was applied. Furthermore, based on the characterization of the causative odorants by gas chromatography-olfactometry and two-dimensional gas chromatography-mass spectrometry/olfactometry, quantitative determination of selected odorants was carried out over time using stable isotope dilution analysis. With regard to the decontamination efficacy of the evaluated decontamination process, we observed that the decrease in the concentration profiles of the monitored odorants went along with a sensorially relevant overall odor minimization of the recycled HDPE. The results of the study are aiding the adaptation of technological procedures for smell reduction or complete decontamination

Characterization of odorous contaminants in post-consumer plastic packaging waste using multidimensional gas chromatographic separation coupled with olfactometric resolution

The increasing world population with their growing consumption of goods escalates the issue of sustainability concepts with increasing demands in recycling technologies. Recovery of post-consumer packaging waste is a major topic in this respect. However, contamination with odorous constituents currently curtails the production of recycling products that meet the high expectations of both consumers and industry. To guarantee odor-free recyclates, the main prerequisite is to characterize the molecular composition of the causative odorants in post-consumer plastic packaging waste. However, targeted characterization of odorous trace contaminants among an abundance of volatiles is a major challenge and requires specialized and high-resolution analytical approaches. For this aim, post-consumer packaging waste was characterized by sensory analysis and two-dimensional high resolution gas chromatography coupled with mass spectrometry and olfactometry. The 33 identified odorants represent various structural classes as well as a great diversity of smell impressions with some of the compounds being identified in plastics for the first time. Substances unraveled within this study provide insights into sources of odorous contamination that will require specific attention in the future in terms of screening and prevention in recycling products

Odorant composition of post-consumer LDPE bags originating from different collection systems

The establishment of recycling systems aiming at high-quality recyclates from post-consumer plastic waste are essential to avoid the waste of resources. One main impediment for introducing recyclates into the market is their unwanted odor. For this reason, this study aimed at determining if the collection strategy affects the odor profile of post-consumer LDPE bags. Furthermore, the effect of hot water washing, inspired by the conventional mechanical recycling procedure, on the odor of post-consumer LDPE bags was screened. More than 60 odorants were detected in LDPE bags collected in a separate plastic fraction as well as in LDPE bags from the non-separated collection by means of gas chromatography-olfactometry, and 37 of them were unequivocally identified using two-dimensional gas chromatography-mass spectrometry/olfactometry. The sensory results revealed that the type of collection affects the overall odor intensity, the hedonic tone of the odor and the odor profile. Namely, cheesy and fecal smelling odorants were predominant in the waste that had not been separated at source, whereas odorants with earthy and moldy smells showed mostly higher intensity ratings in the waste separated at source. Short chain carboxylic acids, likely originating from microbial spoilage of organic waste, were found with higher dilution factors in the mixed fraction, and could, accordingly, contribute to the observed differences. Additionally, we could show that the hot washing procedure, applied to the LDPE sample from the separate collection system, significantly reduced the overall odor intensity from 8 to 6.3 (0–10 scale). However, the washed waste still showed high smell intensity ratings.Miriam Strangl has been supported by a PhD scholarship provided by the Studienstiftung des Deutschen Volkes. Andrea Cabanes has been supported by a PhD scholarship provided by the University of Alicante and Cadel Deinking as part of the InnoUA Transfer of Knowledge program (Industrial Doctorate)