Identifying Putative Biomarkers of Foodborne Pathogens Using a Metabolomic Approach.

Metabolomics is the study of low molecular weight biochemical molecules (typically <1500 Da) in a defined biological organism or system. In case of food systems, the term "food metabolomics" is often used. Food metabolomics has been widely explored and applied in various fields including food analysis, food intake, food traceability, and food safety. Food safety applications focusing on the identification of pathogen-specific biomarkers have been promising. This chapter describes a nontargeted metabolite profiling workflow using gas chromatography coupled with mass spectrometry (GC-MS) for characterizing three globally important foodborne pathogens, Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica, from selective enrichment liquid culture media. The workflow involves a detailed description of food spiking experiments followed by procedures for the extraction of polar metabolites from media, the analysis of the extracts using GC-MS, and finally chemometric data analysis using univariate and multivariate statistical tools to identify potential pathogen-specific biomarkers.

OsRopGEF10 Attenuates Cytokinin Signaling to Regulate Panicle Development and Grain Yield in Rice.

Cytokinins, which play crucial roles in shoot development, substantially affect grain yield. In rice, the OsRopGEF10-OsRAC3 module is associated with cytokinin signaling and crown root development. However, the effects of RopGEF-mediated cytokinin signaling on rice shoot development and grain yield remain unclear. In this study, we investigated the role of OsRopGEF10 in SAM development and the underlying mechanism. We showed that overexpression of OsRopGEF10 inhibited SAM and panicle development, leading to decreased grain yield. Intriguingly, the overexpression of a specific amino acid mutant of OsRopGEF10, designated gef10-W260S, was found to promote panicle development and grain yield. Further analysis using the BiFC assay revealed that the gef10-W260S mutation disrupted the recruitment of rice histidine phosphotransfer proteins (OsAHP1/2) to the plasma membrane (PM), thereby promoting cytokinin signaling. This effect was corroborated by a dark-induced leaf senescence assay, which revealed an increased cytokinin response in the gef10-W260S ectopic expression lines, whereas the overexpression lines presented a suppressed cytokinin response. Moreover, we revealed that the enhanced panicle development in the gef10-W260S lines was attributable to the upregulated expression of several type-B response regulators (RRs) that are crucial for panicle development. Collectively, these findings revealed the negative regulatory function of OsRopGEF10 in the development of the shoot apical meristem (SAM) via interference with cytokinin signaling. Our study highlights the promising role of OsRopGEF10 as a potential target for regulating SAM and panicle development in rice, revealing a valuable breeding strategy for increasing crop yield.

Trapping the substrate radical of heme synthase AhbD.

The heme synthase AhbD catalyzes the last step of the siroheme-dependent heme biosynthesis pathway, which is operative in archaea and sulfate-reducing bacteria. The AhbD-catalyzed reaction consists of the oxidative decarboxylation of two propionate side chains of iron-coproporphyrin III to the corresponding vinyl groups of heme b. AhbD is a Radical SAM enzyme employing radical chemistry to achieve the decarboxylation reaction. Previously, it was proposed that the central iron ion of the substrate iron-coproporphyrin III participates in the reaction by enabling electron transfer from the initially formed substrate radical to an iron-sulfur cluster in AhbD. In this study, we investigated the substrate radical that is formed during AhbD catalysis. While the iron-coproporphyrinyl radical was not detected by electron paramagnetic resonance (EPR) spectroscopy, trapping and visualization of the substrate radical was successful by employing substrate analogs such as coproporphyrin III and zinc-coproporphyrin III. The radical signals detected by EPR were analyzed by simulations based on density functional theory (DFT) calculations. The observed radical species on the substrate analogs indicate that hydrogen atom abstraction takes place at the ß-position of the propionate side chain and that an electron donating ligand is located in proximity to the central metal ion of the porphyrin.

Age-related Changes in Past-Month Alcohol, Cannabis, and Simultaneous Use in a Statewide Sample of Young Adults in Washington State.

OBJECTIVE: It is unknown whether age-related decreases in substance use (maturing out) are observed in the legalized cannabis context. This study evaluated age-related changes in past-month alcohol use frequency, cannabis use frequency, and any simultaneous alcohol and marijuana/cannabis (SAM) use among young adults who engaged in the respective substance use behavior. METHOD: Young adults, residing in Washington State at enrollment (N=6,509; 68.3% female; ages 18-25), provided 3-5 years of annual data in a longitudinal, cohort-sequential design from 2015 to 2019, a period after nonmedical cannabis was legalized and implemented. Multilevel growth models were conducted; post-stratification weights were applied to make the sample more similar to the Washington young adult general population in demographic characteristics. RESULTS: Among those who reported alcohol use at 1+ timepoints, days of alcohol use increased from age 18 to approximately age 25 and then decreased until age 30. Among those who reported cannabis use at 1+ timepoints, days of cannabis use increased from age 18 until approximately age 23 and then decreased until age 30. Among those who reported SAM use at 1+ timepoints, the probability of SAM use increased from age 18 until approximately age 24 and then decreased until age 30. Age-related changes in SAM use were largely explained by concurrent changes in alcohol and cannabis use frequency. CONCLUSIONS: Maturing out was observed for alcohol, cannabis, and SAM use among those who used each respective substance, with evidence that age-related changes in SAM use were tied to alcohol and cannabis use frequency.

Organophosphorus S-adenosyl-L-methionine mimetics: synthesis, stability, and substrate properties.

S-Adenosyl-l-methionine (SAM)-mediated methylation of biomolecules controls their function and regulates numerous vital intracellular processes. Analogs of SAM with a reporter group in place of the S-methyl group are widely used to study these processes. However, many of these analogs are chemically unstable that largely limits their practical application. We have developed a new compound, SAM-P H , which contains an H-phosphinic group (-P(O)(H)OH) instead of the SAM carboxylic group. SAM-P H is significantly more stable than SAM, retains functional activity in catechol-O-methyltransferase and methyltransferase WBSCR27 reactions. The last is associated with Williams-Beuren syndrome. Rac-SAM-P H was synthesized chemically, while (R,S)-SAM-P H and its analogs were prepared enzymatically either from H-phosphinic analogs of methionine (Met-PH) or H-phosphinic analog of S-adenosyl-l-homocysteine (SAH-P H ) using methionine adenosyltransferase 2A or halide methyltransferases, respectively. SAH-P H undergoes glycoside bond cleavage in the presence of methylthioadenosine nucleosidase like natural SAH. Thus, SAM-P H and its analogs are promising new tools for investigating methyltransferases and incorporating reporter groups into their substrates.

Time to recovery and its predictors among children aged 6-59 months having uncomplicated severe acute malnutrition attending an outpatient therapeutic program in Northeast Ethiopia: prospective cohort study.

Introduction: There are insufficient data regarding the variables influencing recovery times, despite the accessible outpatient therapy program (OTP) bringing services for treating severe acute malnutrition (SAM) closer to the community. Therefore, this study aimed to identify the factors influencing the recovery duration in children with uncomplicated SAM between the ages of 6 and 59 months who were attending an OTP in North Wollo, northern Ethiopia. Methods: From February 2021 to July 2021, 356 children, ages 6-59 months, enrolled in a facility-based prospective cohort study. An interviewer administered a semi-structured questionnaire once a week to acquire anthropometric measures. The data were imported into Stata version 14.2 for analysis from EPI data entry version 4.6.06. The time to recovery for each attribute was determined using a log-rank test, a survival curve, and a Kaplan-Meier estimate of the median time to recovery. The Cox Proportional-Hazards Model was used to identify independent predictors of recovery time; statistical significance was indicated at 95% CI and a p-value of 0.05. Results: With a recovery rate of 74.7%, the median recovery period was 56 days. Frequency of growth monitoring and promotion (GMP) service utilization [AHR = 1.622 (95% CI: 1.052-2.130)], cough [AHR = 0.385 (95% CI: 0.176-0.843)], maternal delivery at health center [AHR = 1.448 (95% CI: 1.023-2.050)], and maternal literacy [AHR = 1.445 (95% CI: 1.019-2.058)] were determinants of time to recovery. Conclusion: The median recovery period was 56 days with a recovery rate of 74.7%. Regular utilization of GMP services, maternal delivery at the health center, and cough at admission were independent predictors for this study. As a result, there should be a greater emphasis on the importance of girls' (future mothers') education and nutrition counseling, particularly the integration of GMP service components into institutional delivery/for girls/women who have received little education on how to improve time to recovery and the success of the OTP.

Novel Water Probe for High-Frequency Focused Transducer Applied to Scanning Acoustic Microscopy System: Simulation and Experimental Investigation.

A scanning acoustic microscopy (SAM) system is a common non-destructive instrument which is used to evaluate the material quality in scientific and industrial applications. Technically, the tested sample is immersed in water during the scanning process. Therefore, a robot arm is incorporated into the SAM system to transfer the sample for in-line inspection, which makes the system complex and increases time consumption. The main aim of this study is to develop a novel water probe for the SAM system, that is, a waterstream. During the scanning process, water was supplied using a waterstream instead of immersing the sample in the water, which leads to a simple design of an automotive SAM system and a reduction in time consumption. In addition, using a waterstream in the SAM system can avoid contamination of the sample due to immersion in water for long-time scanning. Waterstream was designed based on the measured focal length calculation of the transducer and simulated to investigate the internal flow characteristics. To validate the simulation results, the waterstream was prototyped and applied to the TSAM-400 and W-FSAM traditional and fast SAM systems to successfully image some samples such as carbon fiber-reinforced polymers, a printed circuit board, and a 6-inch wafer. These results demonstrate the design method of the water probe applied to the SAM system.

Prevalence of Acute Bacterial Infections and Their Antibiotic Sensitivity Pattern in Children With Severe Acute Malnutrition From a Tertiary Care Hospital of Odisha.

Background and objective Malnutrition remains a significant cause of childhood morbidity and mortality worldwide. Severe acute malnutrition (SAM) profoundly affects immune development, physiological functions, and metabolic processes, increasing susceptibility to infections. This study aimed to investigate the prevalence of acute bacterial infections and their antibiotic sensitivity patterns among SAM children admitted to a tertiary care hospital. Methodology This prospective observational study was conducted at the pediatric department of Kalinga Institute of Medical Sciences (KIMS), Bhubaneswar, Odisha, from November 2020 to October 2023. The study included 95 children aged 6-59 months meeting WHO criteria for SAM. Participants underwent comprehensive demographic assessments, clinical evaluations, and relevant laboratory tests, including blood and urine cultures with sensitivity testing. Results The study found that 82.1% of children had weight-for-height below -3 standard deviations, and 84.21% had mid-upper arm circumference below 115 mm, confirming SAM diagnosis. The most prevalent infections were acute gastroenteritis (47.3%), respiratory tract infections (46.3%), bacteremia (27.4%), and urinary tract infections (26.3%). Positive urine cultures were observed in 25 cases (26.3%), predominantly among females (68%). Escherichia coli (40%) and Klebsiella pneumoniae (24%) were the most common organisms isolated from urine, with high sensitivity to gentamicin (76%) and meropenem (72%). Blood cultures were positive in 26 cases (27.36%), with Staphylococcus aureus ​​​​​​(30.76%) and Klebsiella pneumoniae (23%) being predominant. Blood isolates showed significant sensitivity to vancomycin (73%), meropenem (69.2%), and linezolid (65.3%).  Conclusion Acute gastroenteritis, respiratory tract infections, bacteremia, and urinary tract infections are prevalent among SAM children. Staphylococcus aureus was frequently isolated from blood cultures, while Escherichia coli were predominant in urine cultures. High sensitivity of urinary isolates to gentamicin and meropenem, and of blood isolates to vancomycin, meropenem, and linezolid, highlights effective antibiotic choices. These findings emphasize the importance of tailored antimicrobial therapy based on local sensitivity patterns to improve clinical outcomes in SAM children.

A Retinal Vessel Segmentation Method Based on the Sharpness-Aware Minimization Model.

Retinal vessel segmentation is crucial for diagnosing and monitoring various eye diseases such as diabetic retinopathy, glaucoma, and hypertension. In this study, we examine how sharpness-aware minimization (SAM) can improve RF-UNet's generalization performance. RF-UNet is a novel model for retinal vessel segmentation. We focused our experiments on the digital retinal images for vessel extraction (DRIVE) dataset, which is a benchmark for retinal vessel segmentation, and our test results show that adding SAM to the training procedure leads to notable improvements. Compared to the non-SAM model (training loss of 0.45709 and validation loss of 0.40266), the SAM-trained RF-UNet model achieved a significant reduction in both training loss (0.094225) and validation loss (0.08053). Furthermore, compared to the non-SAM model (training accuracy of 0.90169 and validation accuracy of 0.93999), the SAM-trained model demonstrated higher training accuracy (0.96225) and validation accuracy (0.96821). Additionally, the model performed better in terms of sensitivity, specificity, AUC, and F1 score, indicating improved generalization to unseen data. Our results corroborate the notion that SAM facilitates the learning of flatter minima, thereby improving generalization, and are consistent with other research highlighting the advantages of advanced optimization methods. With wider implications for other medical imaging tasks, these results imply that SAM can successfully reduce overfitting and enhance the robustness of retinal vessel segmentation models. Prospective research avenues encompass verifying the model on vaster and more diverse datasets and investigating its practical implementation in real-world clinical situations.

Methyltransferases from RiPP pathways: shaping the landscape of natural product chemistry.

This review article aims to highlight the role of methyltransferases within the context of ribosomally synthesised and post-translationally modified peptide (RiPP) natural products. Methyltransferases play a pivotal role in the biosynthesis of diverse natural products with unique chemical structures and bioactivities. They are highly chemo-, regio-, and stereoselective allowing methylation at various positions. The different possible acceptor regions in ribosomally synthesised peptides are described in this article. Furthermore, we will discuss the potential application of these methyltransferases as powerful biocatalytic tools in the synthesis of modified peptides and other bioactive compounds. By providing an overview of the various methylation options available, this review is intended to emphasise the biocatalytic potential of RiPP methyltransferases and their impact on the field of natural product chemistry.

Heightened SAM- and HPA-axis activity during acute stress impairs decision-making: A systematic review on underlying neuropharmacological mechanisms.

Individuals might be exposed to intense acute stress while having to make decisions with far-reaching consequences. Acute stress impairs processes required for decision-making by activating different biological stress cascades that in turn affect the brain. By knowing which stress system, brain areas, and receptors are responsible for compromised decision-making processes, we can effectively find potential pharmaceutics that can prevent the deteriorating effects of acute stress. We used a systematic review procedure and found 44 articles providing information on this topic. Decision-making processes could be subdivided into 4 domains (cognitive, motivational, affective, and predictability) and could be referenced to specific brain areas, while mostly being impaired by molecules associated with the sympathetic-adrenal-medullar and hypothalamic-pituitary-adrenal axes. Potential drugs to alleviate these effects included α1 and ß adrenoceptor antagonists, α2 adrenoceptor agonists, and corticotropin releasing factor receptor1/2 antagonists, while consistent stress-like effects were found with yohimbine, an α2 adrenoceptor antagonist. We suggest possible avenues for future research.

A New Approach for Super Resolution Object Detection Using an Image Slicing Algorithm and the Segment Anything Model.

Object detection in high resolution enables the identification and localization of objects for monitoring critical areas with precision. Although there have been improvements in object detection at high resolution, the variety of object scales, as well as the diversity of backgrounds and textures in high-resolution images, make it challenging for detectors to generalize successfully. This study introduces a new method for object detection in high-resolution images. The pre-processing stage of the method includes ISA and SAM to slice the input image and segment the objects in bounding boxes, respectively. In order to improve the resolution in the slices, the first layer of YOLO is designed as SRGAN. Thus, before applying YOLO detection, the resolution of the sliced images is increased to improve features. The proposed system is evaluated on xView and VisDrone datasets for object detection algorithms in satellite and aerial imagery contexts. The success of the algorithm is presented in four different YOLO architectures integrated with SRGAN. According to comparative evaluations, the proposed system with Yolov5 and Yolov8 produces the best results on xView and VisDrone datasets, respectively. Based on the comparisons with the literature, our proposed system produces better results.

On the need to integrate interannual natural variability into coastal multihazard assessments.

The co-occurrence of multiple hazards can either exacerbate or mitigate risks. The interrelationships between multiple hazards greatly depend on the spatiotemporal scale and can be difficult to detect from large to local scales. In this paper, we identified coastal regions worldwide where the leading tropical (El Niño-Southern Oscillation, ENSO) and polar (Arctic Oscillation, AO; Southern Annular Mode, SAM) modes of climate variability simultaneously modify the seasonal conditions of multiple hazards, including the near-surface wind speed and swell and wind-sea wave powers. We classified the results at the national and municipal levels, with a focus on multiple hazards simultaneously occurring in space and time. The results revealed that the ENSO modulates multiple hazards, affecting approximately 40% of coastal countries, while the polar annular modes affect approximately 30% of coastal countries. The ENSO induced a greater diversity of multiple hazards, with Asian countries (e.g., Indonesia experienced increases of + 2% in wind and + 7% in swell) and countries in the Americas (e.g., Peru exhibited increases of + 1.5% in wind and + 6% in wind-sea) the most notably affected. The SAM imposed a greater influence on swells in the eastern countries of ocean basins (+ 2.5% in Chile) than in other countries, while the influence of the AO was greater in Norway and the UK (+ 12% for wind-sea and 8% for swell). Low-lying islands exhibited notable variations in pairwise hazards between phases and seasons. Our results could facilitate the interpretation of multihazard interactions and pave the way for a wide range of potential implementations of different coastal industries.

Simultaneous use of alcohol and cannabis and attenuated age-related declines in alcohol and cannabis use disorder symptoms across young adulthood.

Most young adults naturally mature out of high-risk substance use patterns, but it is important to identify factors that may impede normative declines. Use of alcohol and cannabis simultaneously (i.e., simultaneous alcohol and marijuana/cannabis [SAM]) is cross-sectionally associated with alcohol and cannabis concerns, and SAM use increases acute risks at the daily level. However, less is known about long-term risks of SAM use and, specifically, how SAM use relates to maturing out of alcohol and cannabis use. Using four consecutive years of survey data from young adults who reported SAM use (N=409; 1636 responses; aged 18-25 at baseline), we first estimated age-related changes in symptoms of alcohol and cannabis use disorder (AUD/CUD) using multilevel growth modeling. Findings supported a maturing out process, as both AUD and CUD symptom severity significantly declined across young adulthood, on average (4 % and 5 % per year respectively, with significant acceleration). Cross-level interactions tested whether participants' mean SAM use frequency across all four timepoints moderated age-related trajectories in AUD/CUD symptom severity. Significant interactions indicated that, relative to less-frequent SAM use, participants with more frequent SAM use showed less steep declines in AUD (1 % decrease per year vs. 6 % per year) and CUD symptoms (0 % decrease per year vs. 7 % per year); thus, SAM frequency was associated with slower/delayed maturing out of hazardous alcohol and cannabis use. Findings highlight that SAM use may be a correlate or risk-factor for prolonged high-risk substance use during young adulthood that relates to deviations from maturing out processes.

Dietary methionine functions in proliferative zone maintenance and production of eggs via sams-1 in Caenorhabditis elegans.

The maintenance of germ cells is critical for the prosperity of offspring. The amount of food consumption is known to be closely related to reproduction, i.e., the number of eggs decreases under calorie-restricted conditions in various organisms. Previous studies in Caenorhabditis elegans have reported that calorie restriction reduces the number of eggs and the reduction can be rescued by methionine. However, the effect of methionine on the reproductive process has not been fully understood. In this study, to assess the gonadal function of methionine metabolism, we firstly demonstrated that a depletion in dietary methionine resulted in reduced levels of S-adenosyl-l-methionine (SAM) and S-adenosyl homocysteine (SAH) in wild-type N2, but not in glp-1 mutants, which possess only a few germ cells. Second, we found no recovery in egg numbers upon methionine administration in SAM synthase (sams)-1 mutants. Furthermore, a reduced number of proliferative zone nuclei exhibited in the sams-1 mutants was not rescued via methionine. Thus, our results have shown that dietary methionine is required for the normal establishment of both the germline progenitor pool and fecundity, mediated by sams-1.

Large Foundation Model for Cancer Segmentation.

Recently, large language models such as ChatGPT have made huge strides in understanding and generating human-like text and have demonstrated considerable success in natural language processing. These foundation models also perform well in computer vision. However, there is a growing need to use these technologies for specific medical tasks, especially for identifying cancer in images. This paper looks at how these foundation models, such as the segment anything model, could be used for cancer segmentation, discussing the potential benefits and challenges of applying large foundation models to help with cancer diagnoses.

Are Colpodella Species Pathogenic? Nutrient Uptake and Approaches to Diagnose Infections.

Colpodella species are free-living protists phylogenetically related to apicomplexans. Colpodella sp. have been detected in human and animal tissues, as well as in ticks and biting flies. The trophozoite and cyst stages of Colpodella species can be distinguished from stages of the prey Parabodo caudatus using Sam-Yellowe's trichrome staining. Colpodella species obtain nutrients by attaching to their prey, aspirating the prey's cytoplasmic contents into a posterior food vacuole and encysting. It is unclear whether both trophozoite and cyst stages are present in human and animal tissues. Molecular techniques have detected Colpodella species in human blood, cerebrospinal fluid, and in ticks and flies. However, no morphological information was reported to aid life-cycle stage identification of Colpodella species. This review discusses the increased reports of Colpodella species detection in animals and in arthropods and the need to identify stages present in human and animal tissues. We previously used Sam-Yellowe's trichrome staining to identify life-cycle stages of Colpodella sp. In this review, we examine the reports of Colpodella species detection in human and animal tissues to determine whether the identification of Colpodella species represents true infections or contaminations of samples collected during routine surveillance of piroplasm infections in animals and arthropods. This review also aims to provide insights regarding Colpodella, nutrient uptake, and the survival of Colpodella sp. within humans, animals, and arthropods, as well as whether the attachment of trophozoites to cells occurs in tissues leading to myzocytosis and endocytosis.

Bifidobacterium bifidum SAM-VI Riboswitch Conformation Change Requires Peripheral Helix Formation.

The Bifidobacterium bifidum SAM-VI riboswitch undergoes dynamic conformational changes that modulate downstream gene expression. Traditional structural methods such as crystallography capture the bound conformation at high resolution, and additional efforts would reveal details from the dynamic transition. Here, we revealed a transcription-dependent conformation model for Bifidobacterium bifidum SAM-VI riboswitch. In this study, we combine small-angle X-ray scattering, chemical probing, and isothermal titration calorimetry to unveil the ligand-binding properties and conformational changes of the Bifidobacterium bifidum SAM-VI riboswitch and its variants. Our results suggest that the SAM-VI riboswitch contains a pre-organized ligand-binding pocket and stabilizes into the bound conformation upon binding to SAM. Whether the P1 stem formed and variations in length critically influence the conformational dynamics of the SAM-VI riboswitch. Our study provides the basis for artificially engineering the riboswitch by manipulating its peripheral sequences without modifying the SAM-binding core.

Synergy of Rapamycin and Methioninase on Colorectal Cancer Cells Requires Simultaneous and Not Sequential Administration: Implications for mTOR Inhibition.

Background/Aim: Rapamycin inhibits the mTOR protein kinase. Methioninase (rMETase), by degrading methionine, targets the methionine addiction of cancer cells and has been shown to improve the efficacy of chemotherapy drugs, reducing their effective doses. Our previous study demonstrated that rapamycin and rMETase work synergistically against colorectal-cancer cells, but not on normal cells, when administered simultaneously in vitro. In the present study, we aimed to further our previous findings by exploring whether  synergy exists between rapamycin and rMETase when used sequentially against HCT-116 colorectal-carcinoma cells, compared to simultaneous administration, in vitro. Materials and Methods: The half-maximal inhibitory concentrations (IC50) of rapamycin alone and rMETase alone against the HCT-116 human colorectal-cancer cell line were previously determined using the CCK-8 cell viability assay (11). We then examined the efficacy of rapamycin and rMETase, both at their IC50, administered simultaneously or sequentially on the HCT-116 cell line, with rapamycin administered before rMETase and vice versa. Results: The IC50 for rapamycin and rMETase, determined from previous experiments (11), was 1.38 nM and 0.39 U/ml, respectively, of HCT-116 cells. When rMETase was administered four days before rapamycin, both at the IC50, there was a 30.46% inhibition of HCT-116 cells. When rapamycin was administered four days before rMETase, both at the IC50, there was an inhibition of 41.13%. When both rapamycin and rMETase were simultaneously administered, both at the IC50, there was a 71.03% inhibition. Conclusion: Rapamycin and rMETase have synergistic efficacy against colorectal-cancer cells in vitro when administered simultaneously, but not sequentially.

Mechanistic Insights from the Crystal Structure and Computational Analysis of the Radical SAM Deaminase DesII.

Radical S-adenosyl-L-methionine (SAM) enzymes couple the reductive cleavage of SAM to radical-mediated transformations that have proven to be quite broad in scope. DesII is one such enzyme from the biosynthetic pathway of TDP-desosamine where it catalyzes a radical-mediated deamination. Previous studies have suggested that this reaction proceeds via direct elimination of ammonia from an α-hydroxyalkyl radical or its conjugate base (i.e., a ketyl radical) rather than 1,2-migration of the amino group to form a carbinolamine radical intermediate. However, without a crystal structure, the active site features responsible for this chemistry have remained largely unknown. The crystallographic studies described herein help to fill this gap by providing a structural description of the DesII active site. Computational analyses based on the solved crystal structure are consistent with direct elimination and indicate that an active site glutamate residue likely serves as a general base to promote deprotonation of the α-hydroxyalkyl radical intermediate and elimination of the ammonia group.