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The role of polyunsaturated fatty acid (PUFA) biosynthesis in acute myeloid leukemia (AML) remains largely undefined. A comparative expression analysis of 35 genes encoding fatty acid biosynthesis enzymes showed that fatty acid desaturase 1 (FADS1) was highly expressed across multiple AML subtypes relative to healthy controls and that elevated FADS1 expression correlates with worse overall AML patient survival. Functionally, shRNA-mediated inhibition of FADS1 reduced AML cell growth in vitro and significantly delayed leukemia onset in an AML mouse model. AML cell lines depleted of FADS1 arrested in the G1/S-phase of the cell cycle, acquired characteristics of myeloid maturation and subsequently died. To understand the molecular consequences of FADS1 inhibition, a combination of mass spectrometry-based analysis of complex lipids and gene expression analysis (RNA-seq) was performed. FADS1 inhibition caused AML cells to exhibit significant lipidomic remodeling, including depletion of PUFAs from the phospholipids, phosphatidylserine, and phosphatidylethanolamine. These lipidomic alterations were accompanied by an increase induction of inflammatory and stimulator of interferon genes (STING)-mediated type-1 interferon signaling. Remarkably, genetic deletion of STING largely prevented the AML cell maturation and death phenotypes mediated by FADS1 inhibition. Highlighting the therapeutic implications of these findings, pharmacological blockade of PUFA biosynthesis reduced patient-derived AML cell numbers ex vivo but not that of healthy donor cells. Similarly, STING agonism attenuated patient-derived-AML survival; however, STING activation also reduced healthy granulocyte numbers. Collectively, these data unveil a previously unrecognized importance of PUFA biosynthesis in leukemogenesis and that imbalances in PUFA metabolism can drive STING-mediated AML maturation and death.
Subject(s)
Delta-5 Fatty Acid Desaturase , Fatty Acid Desaturases , Fatty Acids, Unsaturated , Leukemia, Myeloid, Acute , Membrane Proteins , Leukemia, Myeloid, Acute/metabolism , Leukemia, Myeloid, Acute/pathology , Leukemia, Myeloid, Acute/genetics , Animals , Humans , Mice , Fatty Acids, Unsaturated/metabolism , Fatty Acids, Unsaturated/biosynthesis , Fatty Acid Desaturases/metabolism , Fatty Acid Desaturases/genetics , Membrane Proteins/metabolism , Membrane Proteins/genetics , Cell Line, Tumor , Cell Death , Signal TransductionABSTRACT
BACKGROUND: Non-AIDS defining malignancies present a growing challenge for persons with HIV (PWH), yet tailored interventions for timely cancer diagnosis are lacking. The Spanish IMPAC-Neo protocol was designed to compare two comprehensive cancer screening strategies integrated into routine HIV care. This study reports baseline data on the prevalence and types of precancerous lesions and early-stage cancer among participants at enrolment. Acceptability of the procedure was additionally assessed. METHODS: Cross-sectional analysis of a comprehensive screening protocol to detect precancer and cancer. The readiness of healthcare providers to implement the protocol was evaluated using a validated 4-item survey. RESULTS: Among the 1430 enrolled PWH, 1172 underwent 3181 screening tests, with positive findings in 29.4% of cases, leading to further investigation in 20.7%. Adherence to the protocol was 84%, with HIV providers expressing high acceptability (97.1%), appropriateness (91.4%), and feasibility (77.1%). A total of 145 lesions were identified in 109 participants, including 60 precancerous lesions in 35 patients (3.0%), 9 early-stage cancers in 9 patients (0.8%), and 76 low-risk lesions in 65 subjects (5.5%). Adverse events related to screening occurred in 0.8% of participants, all mild. The overall prevalence of cancer precursors or early-stage cancer was 3.8% (95% CI, 2.74%-5.01%), with highest rates observed in individuals screened for anal and colorectal cancers. CONCLUSIONS: The baseline comprehensive cancer screening protocol of the IMPAC-Neo study successfully identified a significant proportion of PWH with precancerous lesions and early-stage cancer. High adherence rates and positive feedback from providers suggest effective implementation potential in real-world healthcare settings.
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INTRODUCTION: The DOLAM trial revealed that switching from triple antiretroviral therapy (three-drug regimen; 3DR) to dolutegravir plus lamivudine (two-drug regimen; 2DR) was virologically non-inferior to continuing 3DR after 48â weeks of follow-up. Weight increased with 2DR relative to 3DR but it did not impact on metabolic parameters. METHODS: Multiomics plasma profile was performed to gain further insight into whether this therapy switch might affect specific biological pathways. DOLAM (EudraCT 201500027435) is a Phase 4, randomized, open-label, non-inferiority trial in which virologically suppressed persons with HIV treated with 3DR were assigned (1:1) to switch to 2DR or to continue 3DR for 48â weeks. Untargeted proteomics, metabolomics and lipidomics analyses were performed at baseline and at 48â weeks. Univariate and multivariate analyses were performed to identify changes in key molecules between both therapy arms. RESULTS: Switching from 3DR to 2DR showed a multiomic impact on circulating plasma concentration of N-acetylmuramoyl-L-alanine amidase (Q96PD5), insulin-like growth factor-binding protein 3 (A6XND0), alanine and triglyceride (TG) (48:0). Correlation analyses identified an association among the up-regulation of these four molecules in persons treated with 2DR. CONCLUSIONS: Untargeted multiomics profiling studies identified molecular changes potentially associated with inflammation immune pathways, and with lipid and glucose metabolism. Although these changes could be associated with potential metabolic or cardiovascular consequences, their clinical significance remains uncertain. Further work is needed to confirm these findings and to assess their long-term clinical consequences.
Subject(s)
HIV Infections , Heterocyclic Compounds, 3-Ring , Lamivudine , Oxazines , Piperazines , Pyridones , Humans , Heterocyclic Compounds, 3-Ring/therapeutic use , Heterocyclic Compounds, 3-Ring/administration & dosage , HIV Infections/drug therapy , Lamivudine/therapeutic use , Lamivudine/administration & dosage , Male , Oxazines/therapeutic use , Female , Adult , Middle Aged , Metabolomics , Lipidomics , Anti-HIV Agents/therapeutic use , Anti-HIV Agents/administration & dosage , Plasma/chemistry , Proteomics , Antiretroviral Therapy, Highly Active , Drug Substitution , Triglycerides/blood , Alanine/blood , MultiomicsABSTRACT
BACKGROUND: The use of bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) is based on the results of robust clinical trials. OBJECTIVES: To assess the effectiveness and safety of BIC/FTC/TAF in treatment-naïve (TN) and treatment-experienced (TE) people with HIV using available real-world cohort studies. METHODS: Systematic review and meta-analysis of publications and communications identified via Boolean search in Medline, PubMed and Embase, and conference abstracts reporting retrospective real-world use of BIC/FTC/TAF, published until 31 January 2024. The primary endpoint was the proportion of TN and TE people with HIV with viral load (VL)â<â50â copies/mL at 48â weeks while on treatment. RESULTS: Of the 38 identified publications and conference abstracts, for the present analysis we included 12 publications (comprising 792 TN and 6732 TE individuals). For the three publications including 507 TN participants reporting the primary outcome, VL suppression was 97% [95% confidence intervals (CI): 89-100]. For the nine publications including 4946 TE participants reporting the primary outcome, VL suppression was 95% (95% CI: 94-96), with suppression >93% in all studies. Total discontinuations at 48â weeks in TE individuals were 3% (95% CI: 2-5), 1% (95% CI: 0-2) due to side effects. A total of four publications with 151 TE individuals with previous presence of M184V substitution were identified, reporting a suppression rate at 48â weeks of 95% (95% CI: 88-100). CONCLUSIONS: Real-world studies demonstrate low discontinuation rates and high rates of virologic suppression in individuals treated with BIC/FTC/TAF, both TN and TE with and without previous detection of M184V substitution.
Subject(s)
Alanine , Anti-HIV Agents , Emtricitabine , HIV Infections , Heterocyclic Compounds, 3-Ring , Heterocyclic Compounds, 4 or More Rings , Tenofovir , Viral Load , Humans , HIV Infections/drug therapy , Tenofovir/therapeutic use , Tenofovir/administration & dosage , Tenofovir/analogs & derivatives , Anti-HIV Agents/therapeutic use , Anti-HIV Agents/administration & dosage , Anti-HIV Agents/adverse effects , Emtricitabine/therapeutic use , Emtricitabine/administration & dosage , Heterocyclic Compounds, 4 or More Rings/therapeutic use , Heterocyclic Compounds, 4 or More Rings/administration & dosage , Heterocyclic Compounds, 4 or More Rings/adverse effects , Alanine/therapeutic use , Viral Load/drug effects , Heterocyclic Compounds, 3-Ring/therapeutic use , Heterocyclic Compounds, 3-Ring/adverse effects , Heterocyclic Compounds, 3-Ring/administration & dosage , Drug Combinations , Amides/therapeutic use , Piperazines , Pyridones , Adenine/analogs & derivatives , Adenine/therapeutic use , Adenine/adverse effects , Adenine/administration & dosage , Treatment Outcome , HIV-1/drug effects , HIV-1/genetics , Retrospective StudiesABSTRACT
INTRODUCTION: Rapid initiation of ART after HIV diagnosis is recommended for individual and public health benefits. However, certain clinical and ART-related considerations hinder immediate initiation of therapy. METHODS: An open-label, single-arm, single-centre 48-week prospective clinical trial involving ART-naïve HIV-diagnosed adults who started bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) within a week from the first hospital visit, before the availability of baseline laboratory and genotype results. The primary aim was to determine the proportion of people with at least one condition that would hinder immediate initiation of any recommended ART regimen other than BIC/FTC/TAF. Clinicaltrials.gov: NCT04416906. RESULTS: We included 100 participants: 79% men, 64% from Latin America, median age 32 years. According to European AIDS Clinical Society (EACS) and US Department of Health and Human Services 2023 guidelines, 11% (95%CI 6; 19) of participants had at least one condition that made any ART different from BIC/FTC/TAF less appropriate for a rapid ART strategy. Seventy-nine percent of the people started BIC/FTC/TAF within the first 48 hours of their first hospital visit. There were 16 early discontinuations (11 lost to follow-up). By week 48, 92% (95%CI 86; 98) of the participants of the ITT population with observed data achieved viral suppression. Eight grade 3-4 adverse events (AEs), five serious AEs and six ART-related AEs were identified. Adherence remained high. CONCLUSIONS: BIC/FTC/TAF is an optimal treatment for rapid initiation of ART. However, additional strategies to improve retention in care must be implemented.
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OBJECTIVES: To develop consensus data statements and clinical recommendations to provide guidance for improving cardiometabolic health outcomes in people with HIV based on the knowledge and experience of an international panel of experts. METHODS: A targeted literature review including 281 conference presentations, peer-reviewed articles, and background references on cardiometabolic health in adults with HIV published between January 2016 and April 2022 was conducted and used to develop draft consensus data statements. Using a modified Delphi method, an international panel of 16 experts convened in workshops and completed surveys to refine consensus data statements and generate clinical recommendations. RESULTS: Overall, 10 data statements, five data gaps and 14 clinical recommendations achieved consensus. In the data statements, the panel describes increased risk of cardiometabolic health concerns in people with HIV compared with the general population, known risk factors, and the potential impact of antiretroviral therapy. The panel also identified data gaps to inform future research in people with HIV. Finally, in the clinical recommendations, the panel emphasizes the need for a holistic approach to comprehensive care that includes regular assessment of cardiometabolic health, access to cardiometabolic health services, counselling on potential changes in weight after initiating or switching antiretroviral therapy and encouraging a healthy lifestyle to lower cardiometabolic health risk. CONCLUSIONS: On the basis of available data and expert consensus, an international panel developed clinical recommendations to address the increased risk of cardiometabolic disorders in people with HIV to ensure appropriate cardiometabolic health management for this population.
Subject(s)
Cardiovascular Diseases , Consensus , HIV Infections , Humans , HIV Infections/complications , HIV Infections/drug therapy , Delphi Technique , Risk Factors , Cardiometabolic Risk FactorsABSTRACT
The use of computer simulation for binding affinity prediction is growing in drug discovery. However, its wider use is constrained by the accuracy of the free energy calculations. The key sources of error are the force fields used to depict molecular interactions and insufficient sampling of the configurational space. To improve the quality of the force field, we developed a Python-based computational workflow. The workflow described here uses the minimal basis iterative stockholder (MBIS) method to determine atomic charges and Lennard-Jones parameters from the polarized molecular density. This is done by performing electronic structure calculations on various configurations of the ligand when it is both bound and unbound. In addition, we validated a simulation procedure that accounts for the protein and ligand degrees of freedom to precisely calculate binding free energies. This was achieved by comparing the self-adjusted mixture sampling and nonequilibrium thermodynamic integration methods using various protein and ligand conformations. The accuracy of predicting binding affinity is improved by using MBIS-derived force field parameters and a validated simulation procedure. This improvement surpasses the chemical precision for the eight aromatic ligands, reaching a root-mean-square error of 0.7 kcal/mol.
Subject(s)
Muramidase , Protein Binding , Thermodynamics , Muramidase/chemistry , Muramidase/metabolism , Ligands , Electrons , Bacteriophage T4/enzymology , Mutation , Protein Conformation , Molecular Dynamics Simulation , Models, MolecularABSTRACT
HORTON is a free and open-source electronic-structure package written primarily in Python 3 with some underlying C++ components. While HORTON's development has been mainly directed by the research interests of its leading contributing groups, it is designed to be easily modified, extended, and used by other developers of quantum chemistry methods or post-processing techniques. Most importantly, HORTON adheres to modern principles of software development, including modularity, readability, flexibility, comprehensive documentation, automatic testing, version control, and quality-assurance protocols. This article explains how the principles and structure of HORTON have evolved since we started developing it more than a decade ago. We review the features and functionality of the latest HORTON release (version 2.3) and discuss how HORTON is evolving to support electronic structure theory research for the next decade.
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Grid is a free and open-source Python library for constructing numerical grids to integrate, interpolate, and differentiate functions (e.g., molecular properties), with a strong emphasis on facilitating these operations in computational chemistry and conceptual density functional theory. Although designed, maintained, and released as a stand-alone Python library, Grid was originally developed for molecular integration, interpolation, and solving the Poisson equation in the HORTON and ChemTools packages. Grid is designed to be easy to use, extend, and maintain; this is why we use Python and adopt many principles of modern software development, including comprehensive documentation, extensive testing, continuous integration/delivery protocols, and package management. We leverage popular scientific packages, such as NumPy and SciPy, to ensure high efficiency and optimized performance in grid development. This article is the official release note of the Grid library showcasing its unique functionality and scope.
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GBasis is a free and open-source Python library for molecular property computations based on Gaussian basis functions in quantum chemistry. Specifically, GBasis allows one to evaluate functions expanded in Gaussian basis functions (including molecular orbitals, electron density, and reduced density matrices) and to compute functionals of Gaussian basis functions (overlap integrals, one-electron integrals, and two-electron integrals). Unique features of GBasis include supporting evaluation and analytical integration of arbitrary-order derivatives of the density (matrices), computation of a broad range of (screened) Coulomb interactions, and evaluation of overlap integrals of arbitrary numbers of Gaussians in arbitrarily high dimensions. For circumstances where the flexibility of GBasis is less important than high performance, a seamless Python interface to the Libcint C package is provided. GBasis is designed to be easy to use, maintain, and extend following many standards of sustainable software development, including code-quality assurance through continuous integration protocols, extensive testing, comprehensive documentation, up-to-date package management, and continuous delivery. This article marks the official release of the GBasis library, outlining its features, examples, and development.
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This research aims to examine the influence of human skull bone thickness and density on light penetration in PBM therapy across different wavelengths, focusing on how these bone characteristics affect the absorption of therapeutic light. Analyses explored the effect of skull bone density and thickness on light penetration in PBM, specifically using Low-Level Laser Therapy (LLLT) for efficacy prediction. Measurements of bone thickness and density were taken using precise tools. This approach emphasizes LLLT's significance in enhancing PBM outcomes by assessing how bone characteristics influence light penetration. The study revealed no significant correlation between skull bone density and thickness and light penetration capability in photobiomodulation (PBM) therapy, challenging initial expectations. Wavelengths of 405 nm and 665 nm showed stronger correlations with bone density, suggesting a significant yet weak impact. Conversely, wavelengths of 532 nm, 785 nm, 810 nm, 830 nm, 980 nm, and 1064 nm showed low correlations, indicating minimal impact from bone density variations. However, data variability (R2 < 0.4) suggests that neither density nor thickness robustly predicts light power traversing the bone, indicating penetration capability might be more influenced by bone thickness at certain wavelengths. The study finds that the effectiveness of photobiomodulation (PBM) therapy with bone isn't just based on bone density and thickness but involves a complex interplay of factors. These include the bone's chemical and mineral composition, light's wavelength and energy dose, treatment duration and frequency, and the precise location where light is applied on the skull.
Subject(s)
Low-Level Light Therapy , Humans , Bone Density , Skull , Head , RadiometryABSTRACT
This study aimed to comprehensively assess the metabolic, mitochondrial, and inflammatory effects of first-line efavirenz, emtricitabine, and tenofovir disoproxil fumarate (EFV/FTC/TDF) single-tablet regimen (STR) relative to untreated asymptomatic HIV infection. To this end, we analyzed 29 people with HIV (PWH) treated for at least one year with this regimen vs. 33 antiretroviral-naïve PWH. Excellent therapeutic activity was accompanied by significant alterations in metabolic parameters. The treatment group showed increased plasmatic levels of glucose, total cholesterol and its fractions (LDL and HDL), triglycerides, and hepatic enzymes (GGT, ALP); conversely, bilirubin levels (total and indirect fraction) decreased in the treated cohort. Mitochondrial performance was preserved overall and treatment administration even promoted the recovery of mitochondrial DNA (mtDNA) content depleted by the virus, although this was not accompanied by the recovery in some of their encoded proteins (since cytochrome c oxidase II was significantly decreased). Inflammatory profile (TNFα, IL-6), ameliorated after treatment in accordance with viral reduction and the recovery of TNFα levels correlated to mtDNA cell restoration. Thus, although this regimen causes subclinical metabolic alterations, its antiviral and anti-inflammatory properties may be associated with partial improvement in mitochondrial function.
Subject(s)
Alkynes , Anti-HIV Agents , Benzoxazines , Cyclopropanes , DNA, Mitochondrial , Emtricitabine , HIV Infections , Mitochondria , Tenofovir , Humans , HIV Infections/drug therapy , HIV Infections/metabolism , Male , Female , Adult , Mitochondria/metabolism , Mitochondria/drug effects , Benzoxazines/therapeutic use , Benzoxazines/pharmacology , Anti-HIV Agents/therapeutic use , Anti-HIV Agents/adverse effects , Cyclopropanes/therapeutic use , Tenofovir/therapeutic use , Middle Aged , Emtricitabine/therapeutic use , DNA, Mitochondrial/metabolism , InflammationABSTRACT
Hepatocellular carcinoma (HCC) is one of the most common causes of gastrointestinal and hepatobiliary cancer worldwide. Chronic liver disease and cirrhosis persist as the most common risk factors, typically linked to instances of alcohol abuse or viral infections, notably hepatitis B and hepatitis C infection. Diagnosis can be made using patient history and image studies as there is no need for pathological confirmation. The only curative treatment is surgical resection, and in cases where the tumor is unresectable, as the one presented in this case, and when there are no contraindications, the only option is an orthotopic liver transplantation. This malignancy is not only associated with high mortality but also high morbidity associated with severe complications, such as hemorrhage, necrosis, and infection of the tumor. The significant relevance of this case lies in its capacity to illustrate that despite remaining in non-surgical management for months when an acute complication presented, it was timely identified and surgically treated. The emergence of complications, such as necrosis accompanied by abscess formation and intratumoral hemorrhage, represents an indication for prompt surgical management.
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Carboxy-biotin serves as a coenzyme in certain carboxylases, exhibiting the remarkable capability to transfer a carboxy group to specific substrates. This process is made possible by the presence of biotin, a unique molecule that consists of a sulfur-containing tetrahydrothiophene ring fused to a ureido group. It is covalently attached to the enzyme via a flexible linker, allowing for its functionality. Biotin-dependent carboxylases consist of two distinct domains. The first domain (BC) facilitates biotin carboxylation by utilizing ATP, while the second domain (CT) transfers CO2 to the substrate. The process of ATP-dependent carboxylation using bicarbonate in the biotin carboxylase domain (BC) is well-known. However, the precise mechanism by which CO2 is released in the carboxyltransferase domain (CT) is still not fully understood. We employed advanced computational chemistry methods to investigate the decarboxylation process of carboxy-biotin in various molecular environments and different protonation states. Regardless of the polarity of the molecular surroundings, decarboxylation only occurs spontaneously in the protonated form. To determine the protonation state of biotin in different environments, we established an accurate computational chemistry method for calculating the pKa value of carboxy-biotin, reaching sub-kcal/mol accuracy. Based on our findings, nonpolar environments, such as the active site of the carboxyltransferase domain, have the ability to cause the spontaneous release of CO2 from carboxy-biotin. The CO2 release takes place spontaneously from protonated carboxy-biotin, promoting the carboxylation of substrates.
Subject(s)
Biotin , Carbon Dioxide , Biotin/chemistry , Biotin/metabolism , Carbon Dioxide/chemistry , Carbon Dioxide/metabolismABSTRACT
Gastrojejunal anastomosis or gastrojejunostomy (GJ) is a surgical procedure used for allowing gastric emptying, especially in cases where complex reconstructions are needed. One of the less common complications but one of the most relevant in morbidity is the intussusception of the GJ. It requires a high index of suspicion, preoperative optimization of the patient, diagnostic corroboration, and identification of associated complications with the use of contrasted imaging. It was described for the first time by Bozzi in 1914; currently, multiple cases have been described in the literature, being more frequent in bariatric surgeries and reconstructions after distal gastrectomy. In hepatopancreaticobiliary surgery, it is an even uncommon complication. We present the case of a 60-year-old man with intussusception of the efferent loop of the GJ after a pylorus-preserving pancreatoduodenectomy with a Billroth II reconstruction in the setting of malignancy of the extrahepatic bile duct along with our emergency surgical treatment.
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A retroperitoneal ganglioneuroma is an exceptionally rare surgical entity, even more so in pancreaticoduodenal tumors. These well-differentiated neuroepithelial tumors originate in the neural crest, emerge in the sympathetic nervous system, and consist of ganglion cells and stromal Schwann cells. Generally, these tumors, despite being mostly benign, may be associated with venous or arterial vascular involvement. The symptomatology presented will depend on the mass effect due to tumor growth, and surgical excision is the only therapeutic option offered today to these patients. However, encapsulation of the main vessels represents a great surgical complexity. Various surgical approaches have been employed throughout history; however, the current preferred method is an open midline laparotomy, involving an extensive Kocher maneuver and an artery-first approach, aiming for an R0 resection of the tumor with total vascular preservation to the greatest extent possible. We present a case of an R2 resection involving a 95 mm x 85 mm retroperitoneal peripancreatic ganglioneuroma with double vascular involvement (celiac trunk and superior mesenteric artery). The procedure utilized an artery-first approach with total vascular preservation in a 17-year-old woman who had long-standing gastrointestinal symptoms due to the mass effect.
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Giant abdominopelvic tumors continue to present a diagnostic and therapeutic challenge for all surgeons despite all the advances in the world of imaging. Particularly, one of the most important challenges is to determine its probable origin for adequate surgical planning. Even though mostly all of these tumors are benign ovarian tumors, extraordinarily, malignant mural nodules may develop from the wall of these benign tumors, carrying an invariable unfavorable prognosis for the patient. This case highlights the importance of a correct diagnostic approach using ultrasound and abdominal computed tomography scans and confirming the diagnosis through a histopathologic examination. The treatment for these cases is surgical resection and posterior oncological treatment if needed. This case shows how timely treatment is one of the principal determinators of morbidity and mortality.
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The conversion of CO2 by enzymes such as carbonic anhydrase or carboxylases plays a crucial role in many biological processes. However, in situ methods following the microscopic details of CO2 conversion at the active site are limited. Here, we used infrared spectroscopy to study the interaction of CO2, water, bicarbonate, and other reactants with ß-carbonic anhydrase from Escherichia coli (EcCA) and crotonyl-CoA carboxylase/reductase from Kitasatospora setae (KsCcr), two of the fastest CO2-converting enzymes in nature. Our data reveal that KsCcr possesses a so far unknown metal-independent CA-like activity. Site-directed mutagenesis of conserved active site residues combined with molecular dynamics simulations tracing CO2 distributions in the active site of KsCCr identify an 'activated' water molecule forming the hydroxyl anion that attacks CO2 and yields bicarbonate (HCO3-). Computer simulations also explain why substrate binding inhibits the anhydrase activity. Altogether, we demonstrate how in situ infrared spectroscopy combined with molecular dynamics simulations provides a simple yet powerful new approach to investigate the atomistic reaction mechanisms of different enzymes with CO2.