Chemo-biological upcycling of poly(ethylene terephthalate) (PET) developed in this study includes the following key steps: chemo-enzymatic PET depolymerization, biotransformation of terephthalic acid (TPA) into catechol, and its application as a coating agent. Monomeric units were first produced through PET glycolysis into bis(2-hydroxyethyl) terephthalate (BHET), mono(2-hydroxyethyl) terephthalate (MHET), and PET oligomers and enzymatic hydrolysis of these glycolyzed products using Bacillus subtilis esterase (Bs2Est). Bs2Est efficiently hydrolyzed glycolyzed products into TPA as a key enzyme for chemo-enzymatic depolymerization. Furthermore, catechol solution produced from TPA via a whole-cell biotransformation (Escherichia coli) could be directly used for functional coating on various substrates just after simple cell removal from the culture medium without further purification and water-evaporation. This work demonstrates a proof-of-concept of a PET upcycling strategy via a combination of chemo-biological conversion of PET waste into multifunctional coating materials.
Monoamine oxidase-B (MAO-B) has recently emerged as a potential therapeutic target for Alzheimer's disease (AD) because of its association with aberrant gamma-aminobutyric acid (GABA) production in reactive astrocytes. Although short-term treatment with irreversible MAO-B inhibitors, such as selegiline, improves cognitive deficits in AD patients, long-term treatments have shown disappointing results. We show that prolonged treatment with selegiline fails to reduce aberrant astrocytic GABA levels and rescue memory impairment in APP/PS1 mice, an animal model of AD, because of increased activity in compensatory genes for a GABA-synthesizing enzyme, diamine oxidase (DAO). We have developed a potent, highly selective, and reversible MAO-B inhibitor, KDS2010 (IC(50) = 7.6 nM; 12,500-fold selectivity over MAO-A), which overcomes the disadvantages of the irreversible MAO-B inhibitor. Long-term treatment with KDS2010 does not induce compensatory mechanisms, thereby significantly attenuating increased astrocytic GABA levels and astrogliosis, enhancing synaptic transmission, and rescuing learning and memory impairments in APP/PS1 mice.
Activity-based protein profiling (ABPP) has revolutionized the discovery and optimization of active-site ligands across distinct enzyme families, providing a robust platform for in-class selectivity profiling. Nonetheless, this approach is less straightforward for profiling reversible inhibitors and does not access proteins outside the ABPP probe's target profile. While the active-site competitive acyl protein thioesterase 2 inhibitor ML349 (Ki = 120 nM) is highly selective within the serine hydrolase enzyme family, it could still interact with other cellular targets. Here we present a chemoproteomic workflow to enrich and profile candidate ML349-binding proteins. In human cell lysates, biotinylated-ML349 enriches a recurring set of proteins, including metabolite kinases and flavin-dependent oxidoreductases that are potentially enhanced by avidity-driven multimeric interactions. Confirmatory assays by native mass spectrometry and fluorescence polarization quickly rank-ordered these weak off-targets, providing justification to explore ligand interactions and stoichiometry beyond ABPP.
Post-translational S-palmitoylation directs the trafficking and membrane localization of hundreds of cellular proteins, often involving a coordinated palmitoylation cycle that requires both protein acyl transferases (PATs) and acyl protein thioesterases (APTs) to actively redistribute S-palmitoylated proteins toward different cellular membrane compartments. This process is necessary for the trafficking and oncogenic signaling of S-palmitoylated Ras isoforms, and potentially many peripheral membrane proteins. The depalmitoylating enzymes APT1 and APT2 are separately conserved in all vertebrates, suggesting unique functional roles for each enzyme. The recent discovery of the APT isoform-selective inhibitors ML348 and ML349 has opened new possibilities to probe the function of each enzyme, yet it remains unclear how each inhibitor achieves orthogonal inhibition. Herein, we report the high-resolution structure of human APT2 in complex with ML349 (1.64 A), as well as the complementary structure of human APT1 bound to ML348 (1.55 A). Although the overall peptide backbone structures are nearly identical, each inhibitor adopts a distinct conformation within each active site. In APT1, the trifluoromethyl group of ML348 is positioned above the catalytic triad, but in APT2, the sulfonyl group of ML349 forms hydrogen bonds with active site resident waters to indirectly engage the catalytic triad and oxyanion hole. Reciprocal mutagenesis and activity profiling revealed several differing residues surrounding the active site that serve as critical gatekeepers for isoform accessibility and dynamics. Structural and biochemical analysis suggests the inhibitors occupy a putative acyl-binding region, establishing the mechanism for isoform-specific inhibition, hydrolysis of acyl substrates, and structural orthogonality important for future probe development.
Title: The difference in C-reactive protein value between initial and 24 hours follow-up (D-CRP) data as a predictor of mortality in organophosphate poisoned patients Lee JH, Lee YH, Park YH, Kim YH, Hong CK, Cho KW, Hwang SY Ref: Clinical Toxicology (Phila), 51:29, 2013 : PubMed
Background. Organophosphate poisoning is a worldwide concern and there have been many reports about factors involved in the severity and prognosis of toxicity. The aim of this study was to evaluate the relationship between the serum C-reactive protein activity and clinical outcome in acute organophosphate-poisoned patients. Methods. This was a retrospective cohort study conducted from January 2007 to February 2012. Using a multivariate logistic analysis, data on the total population was retrospectively analyzed for association with mortality. The difference in C-reactive protein value between initial and follow-up after 24 hours (D-CRP) was compared in survivors and non-survivors. The D-CRP, APACHE (Acute Physiology and Chronic Health Evaluation) II scoring system and SOFA (Sequential Organ Failure Assessment) score were compared by analyzing receiver operating characteristic (ROC) curves. Results. Among the 96 subjects, 74 survived and 22 died. In the total population, age, BUN, creatinine, APACHE II and SOFA score, MAP, GCS, hematocrit, respiratory rate, albumin, cholinesterase, and the difference in C-reactive protein value between initial and follow-up after 24 hours (D-CRP) were found to be associated with mortality. The fatality rate of organophosphate poisoning was 22.9% and the D-CRP was found to be associated with a significantly higher risk of death in a multiple logistic regression (Odds ratio = 1.178, 95% CI = 1.049-1.322, p = 0.006). Conclusion. The initial serum C-reactive protein and acetylcholinesterase were not found to be associated with the severity of acute organophosphate poisoning. However, the difference in C-reactive protein value between initial and follow-up after 24 hours (D-CRP) was associated with mortality in the total population of patients with acute organophosphate poisoning.
Title: Proteomics-based identification and characterization of biotype-specific carboxylesterase 2 putatively associated with insecticide resistance in Bemisia tabaci Kang S, Lee HJ, Kim YH, Kwon DH, Oh JH, Kim BJ, Lim KJ, Lee S, Hwang SY, Lee SH Ref: Journal of Asia-Pacific Entomology, 15:389, 2012 : PubMed
Proteomic differences between Bemisia tabaci biotypes (B and Q) were investigated by two-dimensional gel electrophoresis in conjunction with mass spectroscopic analysis. Among several protein spots specific to biotype B, carboxylesterase 2 (Coe2) was significantly more expressed in biotype B. Phylogenetic analysis demonstrated the close relationship of Coe2 with Myzus persicae esterase E4. Comparison of full-length cDNA sequences of Coe2 revealed no amino acid differences in functionally important conserved regions between biotypes B and Q. The transcription level of the Coe2 gene (coe2) was 5.8-fold higher in biotype B than in biotype Q, but the coe2 copy number was not different between biotypes, suggesting that the overexpression of Coe2 was due to transcriptional up-regulation. Native isoelectric focusing followed by mass spectrophotometric analysis confirmed that the overexpressed pI 5.7 esterase in biotype B was Coe2. In-gel inhibition of Coe2 by three insecticides indicated the interaction of Coe2 with chlorpyrifos-methyl oxon and permethrin, but not with imidacloprid. These findings suggest that overexpression of Coe2 in biotype B can confer chemical defense against pyrethroid and organophosphate insecticides, perhaps by sequestration and hydrolysis, as seen in M. persicae E4. Finally, utility of Coe2 as a potential biotype-specific protein marker is discussed.
Title: Development of a low-density DNA microarray for diagnosis of target-site mutations of pyrethroid and organophosphate resistance mutations in the whitefly Bemisia tabaci Chung IH, Kang S, Kim YR, Kim JH, Jung JW, Lee S, Lee SH, Hwang SY Ref: Pest Manag Sci, 67:1541, 2011 : PubMed
BACKGROUND: Rapid and accurate detection of mutations related to insecticide resistance is essential for development of resistance management strategies to support sustainable agriculture. The M918V, L925I and T929V mutations of the voltage-gated sodium channel gene (vgsc) and the F392W mutation of the acetylcholinesterase I gene (ace1) are reportedly associated with resistance to pyrethroids and organophosphates, respectively, in Bemisia tabaci. In order to detect known base substitutions in the ace1 and vgsc genes, a low-density microarray with an allele-specific probe was developed. RESULTS: Specific regions of the ace1 and vgsc gene mutations were amplified by multiplex asymmetrical PCR using Cy3-labelled primers, and then the PCR products were hybridised on the microarray. After analysing the probe signal data, the microarray containing 12 allele-specific probes produced a unique pattern of probe signals for field DNA samples of B. tabaci. To determine the optimal cut-off value of each probe, receiver operating characteristic (ROC) curve analysis was conducted using SPSS. Among 60 individual samples, microarray data for 57 samples were consistent with direct sequencing data. CONCLUSION: Although many molecular detection methods have been employed to monitor insecticide resistance, the present microarray provides rapid and accurate identification of target mutations in B. tabaci for resistance management.
Cocolonization of human mucosal surfaces causes frequent encounters between various staphylococcal species, creating opportunities for the horizontal acquisition of mobile genetic elements. The majority of Staphylococcus aureus toxins and virulence factors are encoded on S. aureus pathogenicity islands (SaPIs). Horizontal movement of SaPIs between S. aureus strains plays a role in the evolution of virulent clinical isolates. Although there have been reports of the production of toxic shock syndrome toxin 1 (TSST-1), enterotoxin, and other superantigens by coagulase-negative staphylococci, no associated pathogenicity islands have been found in the genome of Staphylococcus epidermidis, a generally less virulent relative of S. aureus. We show here the first evidence of a composite S. epidermidis pathogenicity island (SePI), the product of multiple insertions in the genome of a clinical isolate. The taxonomic placement of S. epidermidis strain FRI909 was confirmed by a number of biochemical tests and multilocus sequence typing. The genome sequence of this strain was analyzed for other unique gene clusters and their locations. This pathogenicity island encodes and expresses staphylococcal enterotoxin C3 (SEC3) and staphylococcal enterotoxin-like toxin L (SElL), as confirmed by quantitative reverse transcription-PCR (qRT-PCR) and immunoblotting. We present here an initial characterization of this novel pathogenicity island, and we establish that it is stable, expresses enterotoxins, and is not obviously transmissible by phage transduction. We also describe the genome sequence, excision, replication, and packaging of a novel bacteriophage in S. epidermidis FRI909, as well as attempts to mobilize the SePI element by this phage.
The prophylactic efficacy of a combinational patch system containing physostigmine and procyclidine against soman intoxication was evaluated using dogs. Female beagle dogs (body weights 9-10 kg) were shaved on the abdominal side, attached with a matrix-type patch (7x7 cm) containing 1.5% of physostigmine plus 6% procyclidine for 2 days, and challenged with subcutaneous injection of serial doses (2-10 LD50) of soman. Separately, in combination with the patch attachment, atropine (2 mg/dog) plus 2-pralidoxime (600 mg/dog) or atropine plus 1-[([4-(aminocarbonyl)pyridinio]methoxy)methyl]-2-[(hydroxyimino)methyl]pyridiniu m (HI-6, 500 mg/dog) were injected intramuscularly 1 min after soman poisoning. The LD50 value of soman was determined to be 9.1 microg/kg, and high doses (> or = 1.4 LD50) of soman induced salivation, emesis, defecation and diarrhea, tremors and seizures, and recumbency of dogs, leading to 100% mortality in 24 h. The prophylactic patch, which led to mean 18.5-18.8% inhibition of blood cholinesterase activity by physostigmine and mean 7.9-8.3 ng/ml of blood concentration of procyclidine, exerted a high protection ratio (4.7 LD50), in comparison with relatively-low effects of traditional antidotes, atropine plus 2-pralidoxime (2.5 LD50) and atropine plus HI-6 (2.7 LD50). Noteworthy, a synergistic increase in the protection ratio was achieved by the combination of the patch with atropine plus HI-6 (9 LD50), but not with atropine plus 2-pralidoxime (5 LD50). In addition, the patch system markedly attenuated the cholinergic signs and seizures induced by soman, especially when combined with atropine plus HI-6, leading to elimination of brain injuries and physical incapacitation up to 6 LD50 of soman poisoning. Taken together, it is suggested that the patch system containing physostigmine and procyclidine, especially in combination with atropine and HI-6, could be a choice for the quality survival from nerve-agent poisoning.
The efficacy of a combinational prophylactic regimen on the lethality, convulsions, and loss of morphological and functional integrities of the brain induced by an organophosphate soman was investigated in rats. The rats were implanted subcutaneously with osmotic minipumps containing the combinational prophylactic regimen composed of physostigmine, a reversible cholinesterase inhibitor, and procyclidine, an N-methyl-D-aspartate antagonist possessing anticholinergic action, for 3 days, and intoxicated subcutaneously with soman (160 microg/kg, 1.3 LD50). The doses of combinational regimen in minipumps were optimized to achieve 30-35% inhibition of blood cholinesterase activity by physostigmine and 50-100 ng/ml of blood concentrations of procyclidine as clinically available doses, respectively. In comparison, 1-[([4-(aminocarbonyl)pyridinio]methoxy)methyl]-2-[(hydroxyimino)methyl]pyridiniu m (HI-6, 125 mg/kg) was administered intraperitoneally 30 min prior to the soman challenge in control groups to reduce mortality of rats without affecting convulsions. Soman induced profound limbic convulsions and 30% mortality, leading to increased blood-brain barrier permeability, neural injuries, learning and memory impairments, and physical incapacitation of survived rats pretreated with HI-6. The combinational regimen, at optimal doses without adverse effects on passive avoidance performances (72 microg/kg/h of physostigmine plus 432 microg/kg/h of procyclidine), exerted full protective effects against lethality, convulsions, blood-brain barrier opening, brain injuries, learning and memory impairments, and physical incapacitation induced by soman. Taken together, it is suggested that the combination of physostigmine and procyclidine, at adequate doses, could be a choice to provide the victims of organophosphate poisoning with chance of intensive care for survival and neuroprotection.
While screening extracts of natural products in search of anticholinesterase activity, we found that a total methanolic extract of the tuber of Corydalis ternata (Papaveraceae) showed significant inhibitory effects on acetylcholinesterase. Further fractionation of this extract using acetylcholinesterase inhibition as the parameter screened resulted in the isolation and purification of an alkaloid, protopine. Protopine inhibited acetylcholinesterase activity in a dose-dependent manner. The concentration required for 50% inhibition was 50 microM. The anti-acetylcholinesterase activity of protopine was specific reversible and competitive in manner. Furthermore, when mice were pretreated with protopine, the alkaloid significantly alleviated scopolamine-induced memory impairment. In fact, protopine had an efficacy almost identical to that of velnacrine, a tacrine derivative developed by a major drug manufacturer to treat Alzheimer's disease, at an identical therapeutic concentration. We suggest, therefore, that protopine has both anti-acetylcholinesterase and antiamnesic properties that may ultimately hold significant therapeutic value in alleviating certain memory impairments observed in dementia.
