Development, assessment and educational impact of a blended e-learning training program on pharmacovigilance implemented in four African countries.

Introduction: Efforts to improve medication access in low-and middle-income countries, particularly in Sub-Saharan Africa, have made progress, especially in the fight against infectious diseases such as tuberculosis. However, challenges exist in establishing effective pharmacovigilance systems. The PhArmacoVIgilance Africa (PAVIA) project was committed to enhancing pharmacovigilance in Tanzania, Eswatini, Nigeria, and Ethiopia, with an emphasis on anti-tuberculosis drugs, utilizing various methods, including training. This study evaluates the PAVIA training program's effectiveness and its adaptation during the COVID-19 pandemic. Methods: A blended e-learning program, incorporating two courses and a platform for educational materials, was developed. This program, designed to train healthcare professionals in pharmacovigilance, was incorporated into a Training of Trainers model. To evaluate the program effectiveness, we used multiple measures such as assessing knowledge gain through pre-and post-test scores, assessing learners' satisfaction and attitudes via questionnaires, and analyzing Individual Case Safety Reports (ICSRs) in VigiBase to determine the impact on spontaneous reporting systems in the PAVIA countries. Results: 121 learners enrolled in the pilot trainings, including 36 from Tanzania, 34 from Eswatini, 25 from Nigeria, and 26 from Ethiopia. Notably, post-test scores were significantly higher than pre-test scores in all four countries. Following the pilot trainings, multiple step-down training sessions were held in Tanzania, Eswatini, and Nigeria, with a total of 827 learners registering and 421 successfully completing the program. Learners' scores on the post-tests were significantly higher than on the pre-tests for both courses in all three countries. Learners' feedback on the training was overwhelmingly positive. Additionally, a qualitative analysis of ICSRs revealed a substantial increase in reports after the training in Tanzania, Eswatini, and Nigeria. Discussion: An innovative e-learning program trained healthcare professionals in pharmacovigilance and anti-tuberculosis drug safety over 3 years in four PAVIA countries. The program effectively improved participants' knowledge, received positive feedback, and likely had an impact on reporting rates in Tanzania, Eswatini, and Nigeria, although a direct causal link could not be definitively established due to data limitations and other factors, such as the heightened reporting rates associated with COVID-19 vaccines, that could have contributed to the notable increase in ICSRs.

COVID-19 Acute Respiratory Distress Syndrome: Treatment with Helmet CPAP in Respiratory Intermediate Care Unit by Pulmonologists in the Three Italian Pandemic Waves.

COVID-19 Acute Respiratory Distress Syndrome (CARDS) is the most serious complication of COVID-19. The SARS-CoV-2 outbreaks rapidly saturated intensive care unit (ICU), forcing the application of non-invasive respiratory support (NIRS) in respiratory intermediate care unit (RICU). The primary aim of this study is to compare the patients' clinical characteristics and outcomes (Helmet-Continuous Positive Airway Pressure (H-CPAP) success/failure and survival/death). The secondary aim is to evaluate and detect the main predictors of H-CPAP success and survival/death. A total of 515 patients were enrolled in our observational prospective study based on CARDS developed in RICU during the three Italian pandemic waves. All selected patients were treated with H-CPAP. The worst ratio of arterial partial pressure of oxygen (PaO2) and fraction of inspired oxygen (FiO2) PaO2/FiO2 during H-CPAP stratified the subjects into mild, moderate and severe CARDS. H-CPAP success has increased during the three waves (62%, 69% and 77%, respectively) and the mortality rate has decreased (28%, 21% and 13%). H-CPAP success/failure and survival/death were related to the PaO2/FiO2 (worst score) ratio in H-CPAP and to steroids' administration. D-dimer at admission, FiO2 and positive end expiratory pressure (PEEP) were also associated with H-CPAP success. Our study suggests good outcomes with H-CPAP in CARDS in RICU. A widespread use of steroids could play a role.

Drug-Related Hypersensitivity Reactions Leading to Emergency Department: Original Data and Systematic Review.

The aim of the present study is to describe pharmacological characteristics of drug-related allergies and anaphylaxis leading to the emergency department (ED). An 8-year post hoc analysis on the MEREAFaPS Study database was performed (2012−2019). Subjects who experienced drug-related hypersensitivity leading to an ED visit were selected. Logistic regression analyses were used to estimate the reporting odds ratios (RORs) of drug-related allergies and anaphylaxis adjusting for sex, age classes, and ethnicity. In addition, a systematic review of observational studies evaluating drug-related hypersensitivity reactions leading to ED visits in outpatients was performed. Out of 94,073 ED visits, 14.4% cases were drug-related allergies and 0.6% were anaphylaxis. Females accounted for 56%. Multivariate logistic regression showed a higher risk of drug-related allergy among males and all age classes < 65 years, while a higher risk of anaphylaxis was observed for females (ROR 1.20 [1.01−1.42]) and adults (ROR 2.63 [2.21−3.14]). The systematic review included 37 studies. ED visits related to allergy and anaphylaxis ranged from 0.004% to 88%, and drug-related allergies and anaphylaxis ranged from 0.007% to 88%. Both in our analysis and in primary studies, antibacterials, analgesics, and radiocontrast agents were identified as the most common triggers of hypersensitivity.

Mobilization of sulfane sulfur from cysteine desulfurases to the Azotobacter vinelandii sulfurtransferase RhdA.

Mobilization of the L-cysteine sulfur for the persulfuration of the rhodanese of Azotobacter vinelandii, RhdA, can be mediated by the A. vinelandii cysteine desulfurases, IscS and NifS. The amount of cysteine was higher in mutant strains lacking rhdA (MV474) than in wild type. The diazotrophic growth of MV474 was impaired. Taking into account the functional results about rhodanese-like proteins and RhdA itself, it is suggested that RhdA-dependent modulation of L-cysteine levels must deal with a redox-related process.

Analysis of fatal adverse drug events recorded in several Italian emergency departments (the MEREAFaPS study).

Fatal Adverse Events (FADEs) are a major public health problem, and some FADEs could be preventable. The aim of the present study is to describe the frequency, the drugs involved and the preventability in the FADEs collected through the MEREAFaPS Study between 2012 and 2018. All cases including the outcome "death" have been examined. We excluded cases with vaccine-related ADEs, overdose or suicide, and ADEs occurred during the hospitalisation. Two trained assessors evaluated all cases fulfilling the inclusion criteria. ADEs' preventability was evaluated applying the Schumock and Thornton algorithm. During the study period, we observed 429 cases of death, 92 of which were excluded. The remaining 337 cases involved 187 women and 150 men, with a mean age of 79 and of 77 years, respectively. For each report, the suspected drugs and concomitant ones were 1.26 and 4.20, respectively. Anticoagulants and antiplatelet agents account for more than 40% of FADE cases and the most frequent reactions are haemorrhages (37.5%). The 25% of the FADEs were preventable. This study confirms that FADEs are still a relevant clinical occurrence, and are often caused by widely used old drugs associated with adverse events. The death of one in four patients was preventable. Further efforts should be done to improve the appropriateness of the therapy, especially in older patients who are treated with anticoagulants.

Risk of Hospitalization for Adverse Drug Events in Women and Men: A Post Hoc Analysis of an Active Pharmacovigilance Study in Italian Emergency Departments.

This post hoc analysis of an Italian active pharmacovigilance study describes pharmacological differences of ADEs leading to emergency department (ED) visits and hospitalization in women and men. During the study period (January 2007-December 2018), 61,855 reports of ADEs leading to ED visits were collected. Overall, 30.6% of ADEs resulted in hospitalization (30% in women and 31% in men). Multivariate logistic regression showed that, among women, drug classes significantly associated with an increased risk of hospitalization were heparins (ROR 1.41, CI 1.13-176), antidepressants (ROR 1.12, CI 1.03-1.23) and antidiabetics (ROR 1.13, CI 1.02-1.24). Among men, only vitamin K antagonists (ROR 1.28, CI 1.09-1.50), opioids (ROR 1.30, CI 1.06-1.60) and digitalis glycosides (ROR 1.32, CI 1.09-1.59) were associated with a higher risk of hospitalization. Overall, older age, multiple suspected drugs and the presence of comorbidities were significantly associated with a higher risk of hospitalization. A significantly reduced risk of hospitalization was observed in both women and men experiencing an adverse event following immunization (ROR 0.36, CI 0.27-0.48 and 0.83, 0.42-0.74, respectively) compared to drugs. Results obtained from this real-world analysis highlight important aspects of drug safety between sexes.

The rhodanese RhdA helps Azotobacter vinelandii in maintaining cellular redox balance.

The tandem domain rhodanese-homology protein RhdA of Azotobacter vinelandii shows an active-site loop structure that confers structural peculiarity in the environment of its catalytic cysteine residue. The in vivo effects of the lack of RhdA were investigated using an A. vinelandii mutant strain (MV474) in which the rhdA gene was disrupted by deletion. Here, by combining analytical measurements and transcript profiles, we show that deletion of the rhdA gene generates an oxidative stress condition to which A. vinelandii responds by activating defensive mechanisms. In conditions of growth in the presence of the superoxide generator phenazine methosulfate, a stressor-dependent induction of rhdA gene expression was observed, thus highlighting that RhdA is important for A. vinelandii to sustain oxidative stress. The potential of RhdA to buffer general levels of oxidants in A. vinelandii cells via redox reactions involving its cysteine thiol is discussed.

The lack of rhodanese RhdA affects the sensitivity of Azotobacter vinelandii to oxidative events.

The rhdA gene of Azotobacter vinelandii codes for RhdA, a rhodanese-domain protein with an active-site loop structure which has not currently been found in proteins of the rhodanese-homology superfamily. Considering the lack of information on the functional role of the ubiquitous rhodaneses, in the present study we examined the in vivo functions of RhdA by using an A. vinelandii mutant strain (MV474), in which the rhdA gene was disrupted by deletion. Preliminary phenotypic characterization of the rhdA mutant suggested that RhdA could exert protection over Fe-S enzymes, which are easy targets for oxidative damage. To highlight the role of RhdA in preserving sensitive Fe-S clusters, in the present study we analysed the defects of the rhdA-null strain by exploiting growth conditions which resulted in enhancing the catalytic deficiency of enzymes with vulnerable Fe-S clusters. We found that a lack of RhdA impaired A. vinelandii growth in the presence of gluconate, a carbon source that activates the Entner-Doudoroff pathway in which the first enzyme, 6-phosphogluconate dehydratase, employs a 4Fe-4S cluster as an active-site catalyst. By combining proteomics, enzymatic profiles and model systems to generate oxidative stress, evidence is provided that to rescue the effects of a lack of RhdA, A. vinelandii needed to activate defensive activities against oxidative damage. The possible functionality of RhdA as a redox switch which helps A. vinelandii in maintaining the cellular redox balance was investigated by using an in vitro model system that demonstrated reversible chemical modifications in the highly reactive RhdA Cys(230) thiol.

Risk of Hospitalization Associated with Cardiovascular Medications in the Elderly Italian Population: A Nationwide Multicenter Study in Emergency Departments.

Background: There is a significant gap in knowledge addressing cardiovascular (CV) medications safety in elderly. In this context, our purposes were to define clinical and pharmacological characteristics of outpatients' adverse drug events (ADEs) related to CV medications leading to emergency department (ED) visits in the elderly Italian patients according to different age groups, and to evaluate the risk of hospitalization associated to ADEs in this population. Methods: A multicentre, retrospective study was performed on reports of suspected ADEs collected between 2007-2018 in 94 EDs involved in the MEREAFaPS Study. Elderly patients who experienced one or more CV medications-related ADEs leading to ED visit were selected. Patients' characteristics, suspected (ATC classes B and C) and concomitant drugs, and ADE description were collected. Elderly patients were stratified into three age groups (65-74, 75-84, and ≥85 years) and compared to adults (18-64 years). Logistic regression analyses were used to estimate the reporting odds ratios (RORs) with 95% confidence intervals (CIs) of ADE-related hospitalization adjusting for sex, presence of two or more suspected drugs, concomitant drugs, and one or more comorbidities. Results: Among elderly, 16,926 reports of suspected ADE related to CV medications were collected, and 6,694 (39.5%) resulted in hospitalization. Patients were mostly female, Caucasians, and middle-old (75-84). 78.9% of patients were treated with only one suspected drug, and 71.9% and 47.1% reported concomitant medications and comorbidities, respectively. Compared to adults, risk of hospitalization was significantly higher for middle-old and oldest-old patients exposed to vitamin K antagonists (1.29 [1.09-1.52] and 1.56 [1.30-187]), direct thrombin inhibitors (3.41 [1.44-8.08] and 4.12 [1.67-10.17]), antiplatelets (1.51 [1.26-1.81] and 2.09 [1.71-2.57]), and beta-blockers (1.89 [1.38-2.59 and 2.31 [1.60-3.35]). Overall, a higher risk of hospitalization was observed for renin-angiotensin system inhibitors (1.32 [1.04-1.68], 1.65 [1.32-2.06], and 2.20 [1.70-2.85]), presence of two or more concomitant drugs, and concomitant conditions. Conclusion: Our real-world findings underline relevant safety aspects of CV medications in the elderly Italian population. ED clinicians must always consider the higher risk of hospitalization related to the use of CV drugs in elderly, particularly in oldest-old ones, for antiarrhythmics, beta-blocking agents, renin-angiotensin system inhibitors, antiplatelets, and anticoagulants.

Effects of the deficiency of the rhodanese-like protein RhdA in Azotobacter vinelandii.

In Azotobacter vinelandii the rhdA gene codes for a protein (RhdA) of the rhodanese-homology superfamily. By combining proteomics, enzymic profiles and ultrastructural observations, the phenotype of an A. vinelandii rhdA mutant was analyzed. We found that the A. vinelandii rhdA mutant, and not the wild-type strain, accumulated polyhydroxybutyrate. RhdA deficiency enhanced the expression of enzymes of the polyhydroxybutyrate biosynthetic operon, and affected the activity of specific tricarboxylic acid cycle enzymes. The effect was dramatic on aconitase, in spite of comparable expression of aconitase polypeptides in both strains. By using a model system, we found that RhdA triggered protection from oxidants.

The cysteine-desulfurase IscS promotes the production of the rhodanese RhdA in the persulfurated form.

After heterologous expression in Escherichia coli, the Azotobacter vinelandii rhodanese RhdA is purified in a persulfurated form (RhdA-SSH). We identified l-cysteine as the most effective sulfur source in producing RhdA-SSH. An E. coli soluble extract was required for in vitro persulfuration of RhdA, and the addition of pyridoxal-5'-phosphate increased RhdA-SSH production, indicating a likely involvement of a cysteine desulfurase. We were able to show the formation of a covalent complex between IscS and RhdA. By combining a time-course fluorescence assay and mass spectrometry analysis, we demonstrated the transfer of sulfur from E. coli IscS to RhdA.

The "rhodanese" fold and catalytic mechanism of 3-mercaptopyruvate sulfurtransferases: crystal structure of SseA from Escherichia coli.

3-Mercaptopyruvate sulfurtransferases (MSTs) catalyze, in vitro, the transfer of a sulfur atom from substrate to cyanide, yielding pyruvate and thiocyanate as products. They display clear structural homology with the protein fold observed in the rhodanese sulfurtransferase family, composed of two structurally related domains. The role of MSTs in vivo, as well as their detailed molecular mechanisms of action have been little investigated. Here, we report the crystal structure of SseA, a MST from Escherichia coli, which is the first MST three-dimensional structure disclosed to date. SseA displays specific structural differences relative to eukaryotic and prokaryotic rhodaneses. In particular, conformational variation of the rhodanese active site loop, hosting the family invariant catalytic Cys residue, may support a new sulfur transfer mechanism involving Cys237 as the nucleophilic species and His66, Arg102 and Asp262 as residues assisting catalysis.

Social hierarchies and emotions: cortical prefrontal activity, facial feedback (EMG), and cognitive performance in a dynamic interaction.

In the present research, we manipulated the perceived superior/inferior status during a competitive cognitive task. In two experiments, we created an explicit and strongly reinforced social hierarchy based on incidental rating on an attentional task. Based on our hypotheses, social rank may influence nonverbal cues (such as facial mimic related to emotional response), cortical lateralized activity in frontal areas (brain oscillations), and cognitive outcomes in response to rank modulation. Thus, the facial mimic (corrugators vs. zygomatic muscle activity), frequency bands (delta, theta, alpha, beta), and real cognitive performance [(error rate (ER); response times (RTs)] were considered. Specifically, a peer-group comparison was enrolled and an improved (experiment 1, N = 29) or decreased (experiment 2, N = 31) performance was artificially manipulated by the experimenter. Results showed a significant improved cognitive performance (decreased ER and RTs), an increased zygomatic activity (positive emotions), and a more prefrontal left-lateralized cortical response in the case of a perceived increased social ranking. On the contrary, a significant decreased cognitive performance (increased ER and RTs), an increased corrugators activity (negative emotions), and a less left-lateralized cortical response were observed as a consequence of a perceived decreased social ranking. Moreover, the correlational values revealed a consistent trend between behavioral (RTs) and EMG and EEG measures for both experiments. The present results suggest that social status not only guides social behavior, but it also influences cognitive processes and subjects' performance.

The N-terminal rhodanese domain from Azotobacter vinelandii has a stable and folded structure independently of the C-terminal domain.

Sulfurtransferase are enzymes involved in the formation, conversion and transport of compounds containing sulfane-sulfur atoms. Although the three-dimensional structure of the rhodanese from the nitrogen-fixing bacterium Azotobacter vinelandii is known, the role of its two domains in the protein conformational stability is still obscure. We have evaluated the susceptibility to proteolytic degradation of the two domains of the enzyme. The two domains show different resistance to the endoproteinases and, in particular, the N-terminal domain shows to be more stable to digestion during time than the C-terminal one. Cloning and overexpression of the N-terminal domain of the protein was performed to better understand its functional and structural role. The recombinant N-terminal domain of rhodanese A. vinelandii is soluble in water solution and the spectroscopic studies by circular dichroism and heteronuclear NMR spectroscopy indicate a stable fold of the protein with the expected alpha/beta topology. The results indicate that this N-terminal domain has already got all the elements necessary for an C-terminal domain independent folding. Its solution structure by NMR, actually under course, will be a valid contribution to understand the role of this domain in the folding process of the sulfurtransferase.

Structural rearrangements of the two domains of Azotobacter vinelandii rhodanese upon sulfane sulfur release: essential molecular dynamics, 15N NMR relaxation and deuterium exchange on the uniformly labeled protein.

The Azotobacter vinelandii rhodanese is a 31kDa sulfurtransferase protein that catalyzes the transfer of sulfur atom from thiosulfate to cyanide in the detoxification process from cyanide and is able to insert sulfur atom in the iron-sulfur cluster. A study of the uniformly 15N isotopic labeling by high resolution NMR, before obtaining the backbone sequential assignment, has been carried out. The sulfur loaded and the sulfur discharged forms of the enzyme show very similar HSQC spectra with a good spectral dispersion. Few resonances show changes in chemical shift between the two forms. Relaxation parameters T(1), T(2) and 1H-15N NOE of all amide nitrogen atoms, as well as isotope exchange kinetics, show that the two forms exhibit the same global correlation time and hydrodynamic properties. In parallel, essential dynamics studies show that formation and discharging of catalytic cysteine persulfide group has no significant impact on the overall conformation of the protein. These results, taken together, give a clearcut answer to the question if the catalytic mechanism of the enzyme involves a change in the conformation and/or in the mutual orientation of the two domains. On the contrary these results clearly indicate that upon the catalytic mechanism the two domains of the protein behave as a unique fold.

Personality correlates (BAS-BIS), self-perception of social ranking, and cortical (alpha frequency band) modulation in peer-group comparison.

The perception and interpretation of social hierarchies are a key part of our social life. In the present research we considered the activation of cortical areas, mainly the prefrontal cortex, related to social ranking perception in conjunction with some personality components (BAS - Behavioral Activation System - and BIS - Behavioral Inhibition System). In two experiments we manipulated the perceived superior/inferior status during a competitive cognitive task. Indeed, we created an explicit and strongly reinforced social hierarchy based on incidental rating in an attentional task. Specifically, a peer group comparison was undertaken and improved (Experiment 1) or decreased (Experiment 2) performance was artificially manipulated by the experimenter. For each experiment two groups were compared, based on a BAS and BIS dichotomy. Alpha band modulation in prefrontal cortex, behavioral measures (performance: error rate, ER; response times, RTs), and self-perceived ranking were considered. Repeated measures ANOVAs and regression analyses showed in Experiment 1 a significant improved cognitive performance (decreased ER and RTs) and higher self-perceived ranking in high-BAS participants. Moreover, their prefrontal activity was increased within the left side (alpha band decreasing). Conversely, in Experiment 2 a significant decreased cognitive performance (increased ER and RTs) and lower self-perceived ranking was observed in higher-BIS participants. Their prefrontal right activity was increased in comparison with higher BAS. The regression analyses confirmed the significant predictive role of alpha band modulation with respect of subjects' performance and self-perception of social ranking, differently for BAS/BIS components. The present results suggest that social status perception is directly modulated by cortical activity and personality correlates.

Involvement of the Azotobacter vinelandii rhodanese-like protein RhdA in the glutathione regeneration pathway.

The phenotypic features of the Azotobacter vinelandii RhdA mutant MV474 (in which the rhdA gene was deleted) indicated that defects in antioxidant systems in this organism were related to the expression of the tandem-domain rhodanese RhdA. In this work, further insights on the effects of the oxidative imbalance generated by the absence of RhdA (e.g. increased levels of lipid hydroperoxides) are provided. Starting from the evidence that glutathione was depleted in MV474, and using both in silico and in vitro approaches, here we studied the interaction of wild-type RhdA and Cys(230)Ala site-directed RhdA mutant with glutathione species. We found that RhdA was able to bind in vitro reduced glutathione (GSH) and that RhdA-Cys(230) residue was mandatory for the complex formation. RhdA catalyzed glutathione-disulfide formation in the presence of a system generating the glutathione thiyl radical (GS, an oxidized form of GSH), thereby facilitating GSH regeneration. This reaction was negligible when the Cys(230)Ala RhdA mutant was used. The efficiency of RhdA as catalyst in GS-scavenging activity is discussed on the basis of the measured parameters of both interaction with glutathione species and kinetic studies.

Conformational studies on Arabidopsis sulfurtransferase AtStr1 with spectroscopic methods.

Sulfurtransferases/rhodaneses (Str) are enzymes widely distributed in archaea, prokaryota and eukaryota, and catalyze the transfer of sulfur from a donor molecule to a thiophilic acceptor substrate. In this reaction, Str cycles between the sulfur-free and the sulfur-substituted form. Two-domain Str consist of two globular domains of nearly identical size and conformation connected by a short linker sequence, which is elongated in plant two-domain Str proteins compared to Str in other organisms. The two-domain Arabidopsis thaliana Str1 protein (At1g79230) was expressed in Escherichia coli as a mature protein, as a variant without the elongated linker sequence, and as AtStr1C332S and AtStr1C339V. The persulfuration state of the purified recombinant proteins was investigated in the presence and absence of sulfur donors by fluorescence spectroscopy. The secondary structure was analyzed by circular dichroism (CD) in the far-UV range, while overall changes in tertiary structure were determined by CD in the near-UV range. Finally, protein stability was analyzed by tryptic digestion. The elongated linker sequence is essential for correct conformation and stability, and thereby affects the catalytic activity of AtStr1. Replacement of the catalytic cysteine residue C332 leads to higher rigidity of the molecule, whereas replacement of C339 does not lead to any conformational changes, providing evidence of the direct involvement of C339 in catalysis.

Enzymatic and genetic profiles in environmental strains grown on polycyclic aromatic hydrocarbons.

The possible generation of oxidative stress induced by aromatic hydrocarbon degradation suggests that ancillary enzyme activities could facilitate the utilization of polycyclic aromatic hydrocarbons as sole carbon source. To investigate the metabolic profiles of low molecular weight polycyclic aromatic hydrocarbon-degrading strains of Sphingobium chlorophenolicum, Rhodococcus aetherovorans, Rhodococcus opacus and Mycobacterium smegmatis, the determination of the activity of putative detoxifying enzymes (rhodanese-like and glutathione S-transferase proteins) was combined with genetic analyses. All the studied strains were able to utilize phenanthrene or naphthalene. Glutathione S-transferase activity was found in S. chlorophenolicum strains grown on phenanthrene and it was related to the presence of the bphK gene, since modulation of glutathione S-transferase activity by phenanthrene paralleled the induction of glutathione S-transferase transcript in the S. chlorophenolicum strains. No glutathione S-transferase activity was detectable in R. aetherovorans, R. opacus and in M. smegmatis strains. All strains showed 3-mercaptopyruvate:cyanide sulfurtransferase activity. A rhodanese-like SseA protein was immunodetected in R. aetherovorans, R. opacus and in M. smegmatis strains, where increase of 3-mercaptopyruvate:cyanide sulfurtransferase activity was significantly induced by growth on phenanthrene.

Azotobacter vinelandii rhodanese: selenium loading and ion interaction studies.

Rhodanese is a sulfurtransferase which in vitro catalyzes the transfer of a sulfane sulfur from thiosulfate to cyanide. Ionic interactions of the prokaryotic rhodanese-like protein from Azotobacter vinelandii were studied by fluorescence and NMR spectroscopy. The catalytic Cys230 residue of the enzyme was selectively labelled using [15N]Cys, and changes in 1H and 15N NMR resonances on addition of different ions were monitored. The results clearly indicate that the sulfur transfer is due to a specific reaction of the persulfurated Cys residue with a sulfur acceptor such as cyanide and not to the presence of the anions. Moreover, the 1H-NMR spectrum of a defined spectral region is indicative of the status of the enzyme and can be used to directly monitor sulfur loading even at low concentrations. Selenium loading by the addition of selenodiglutathione was monitored by fluorescence and NMR spectroscopy. It was found to involve a specific interaction between the selenodiglutathione and the catalytic cysteine residue of the enzyme. These results indicate that rhodanese-like proteins may function in the delivery of reactive selenium in vivo.