Elucidation of procoagulant mechanism and pathophysiological significance of a new prothrombin activating metalloprotease purified from Daboia russelii russelii venom

A comparison of two different analytical workflows to determine the venom proteome composition of Naja kaouthia from North-East India and immunological profiling of venom against commercial antivenoms

The Indian monocled cobra (Naja kaouthia) is one of the most prevalent venomous snakes in northeast India (NEI) and is the cause of many fatalities. The composition of NEI N. kaouthia venom (NkV) was deciphered using two different proteomic approaches: (i) 1D SDS-PAGE coupled to label-free quantification of protein bands using stringent identification criteria and (ii) reversed-phase high-performance liquid chromatography (RP-HPLC) followed by quantification based on area under the RP-HPLC peaks. The proteomic data from both strategies were compared. Proteomic analyses from both workflows identified 32 proteins (toxins) distributed over 10-14 snake venom protein families in NEI NkV. The relative abundances of the venom proteins determined from the analytical workflows coincided with the densitometry band intensities of the NEI NkV. Phospholipase A₂ (13.1-16.0%) and three-finger toxins (58.5-64.2%) represented the most abundant enzymatic and non-enzymatic proteins in NEI NkV, respectively. Immuno-cross-reactivity studies by enzyme-linked immunoassay and immunoblot analyses pointed to the poor efficacy of commercial PAVs in recognizing the low molecular mass (<15 kDa) toxins of NEI NkV. Spectrofluorometric titration determined the presence of NEI NkV-specific antibodies in commercial PAV, at a level that was higher than that previously reported for eastern India NkV-specific antibodies in commercial antivenom.

A comparative cross-reactivity and paraspecific neutralization study on Hypnale hypnale, Echis carinatus, and Daboia russelii monovalent and therapeutic polyvalent anti-venoms

Envenoming by the hump-nosed pit viper (Hypnale hypnale) raises concern as it inflicts significant debilitation and death in the Western Ghats of India and in the adjacent island nation of Sri Lanka. In India, its medical significance was realized only during 2007 due to its misidentification as Echis carinatus and sometimes as Daboia russelii. Of late, several case reports have underlined the ineptness of the existing polyvalent anti-venom therapy against H. hypnale envenoming. Currently, H. hypnale bite has remained dreadful in India due to the lack of neutralizing anti-venom therapy. Hence, this study was undertaken to establish a systematic comparative, biochemical, pathological, and immunological properties of Sri Lankan H. hypnale venom alongside Indian E. carinatus, and D. russelii venoms. All three venoms differed markedly in the extent of biochemical activities including proteolytic, deoxyribonuclease, L-amino acid oxidase, 5'-nucleotidase, hyaluronidase, and indirect hemolytic activities. The venoms also differed markedly in their pathological properties such as edema, hemorrhage, myotoxic, cardiotoxic, and coagulant activities. The venoms showed stark differences in their protein banding pattern. Strikingly, the affinity-purified rabbit monovalent anti-venoms prepared against H. hypnale, E. carinatus, and D. russelii venoms readily reacted and neutralized the biochemical and pathological properties of their respective venoms, but they insignificantly cross-reacted with, and thus failed to show paraspecific neutralization of any of the effects of the other two venoms, demonstrating the large degree of variations between these venoms. Further, the Indian therapeutic polyvalent anti-venoms from VINS Bioproducts, and Bharath Serums and Vaccines failed to protect H. hypnale venom-induced lethal effects in mice.

A Genus-Wide Bioactivity Analysis of Daboia (Viperinae: Viperidae) Viper Venoms Reveals Widespread Variation in Haemotoxic Properties

The snake genus Daboia (Viperidae: Viperinae; Oppel, 1811) contains five species: D. deserti, D. mauritanica, and D. palaestinae, found in Afro-Arabia, and the Russell's vipers D. russelii and D. siamensis, found in Asia. Russell's vipers are responsible for a major proportion of the medically important snakebites that occur in the regions they inhabit, and their venoms are notorious for their coagulopathic effects. While widely documented, the extent of venom variation within the Russell's vipers is poorly characterised, as is the venom activity of other species within the genus. In this study we investigated variation in the haemotoxic activity of Daboia using twelve venoms from all five species, including multiple variants of D. russelii, D. siamensis, and D. palaestinae. We tested the venoms on human plasma using thromboelastography, dose-response coagulometry analyses, and calibrated automated thrombography, and on human fibrinogen by thromboelastography and fibrinogen gels. We assessed activation of blood factors X and prothrombin by the venoms using fluorometry. Variation in venom activity was evident in all experiments. The Asian species D. russelii and D. siamensis and the African species D. mauritanica possessed procoagulant venom, while D. deserti and D. palaestinae were net-anticoagulant. Of the Russell's vipers, the venom of D. siamensis from Myanmar was most toxic and D. russelli of Sri Lanka the least. Activation of both factor X and prothrombin was evident by all venoms, though at differential levels. Fibrinogenolytic activity varied extensively throughout the genus and followed no phylogenetic trends. This venom variability underpins one of the many challenges facing treatment of Daboia snakebite envenoming. Comprehensive analyses of available antivenoms in neutralising these variable venom activities are therefore of utmost importance.

Assessment of quality and pre-clinical efficacy of a newly developed polyvalent antivenom against the medically important snakes of Sri Lanka

Snake envenomation is a severe problem in Sri Lanka (SL) and Indian polyvalent antivenom (PAV) is mostly used for treating snakebite albeit due to geographical variation in venom composition, Indian PAV shows poor efficacy in neutralizing the lethality and toxicity of venom from the same species of snakes in SL. Therefore, the quality and in vivo venom neutralization potency of a country-specific PAV produced against the venom of the five most medically important snakes of SL (Daboia russelii, Echis carinatus, Hypnale hypnale, Naja naja, Bungarus caeruleus) was assessed. LC-MS/MS analysis of two batches of PAV showed the presence of 88.7-97.2% IgG and traces of other plasma proteins. The tested PAVs contained minor amounts of undigested IgG and F(ab')2 aggregates, showed complement activation, were devoid of IgE, endotoxin, and content of preservative was below the threshold level. Immunological cross-reactivity and in vitro neutralization of enzymatic activities, pharmacological properties demonstrated superior efficacy of SL PAV compared to Indian PAV against SL snake venoms. The in vivo neutralization study showed that the tested PAVs are potent to neutralize the lethality and venom-induced toxicity of SL snake venoms. Therefore, our study suggests that introduction of SL-specific PAV will improve snakebite management in SL.

Proteomics, toxicity and antivenom neutralization of Sri Lankan and Indian Russell's viper (Daboia russelii) venoms

BACKGROUND

The western Russell's viper (Daboia russelii) is widely distributed in South Asia, and geographical venom variation is anticipated among distant populations. Antivenoms used for Russell's viper envenomation are, however, raised typically against snakes from Southern India. The present study investigated and compared the venom proteomes of D. russelii from Sri Lanka (DrSL) and India (DrI), the immunorecognition of Indian VINS Polyvalent Antivenom (VPAV) and its efficacy in neutralizing the venom toxicity.

METHODS

The venoms of DrSL and DrI were decomplexed with C18 high-performance liquid chromatography and SDS-polyacrylamide gel electrophoresis under reducing conditions. The proteins fractionated were identified through nano-ESI-liquid chromatography-tandem mass spectrometry (LCMS/MS). The immunological studies were conducted with enzyme-linked immunosorbent assay. The neutralization of the venom procoagulant effect was evaluated in citrated human plasma. The neutralization of the venom lethality was assessed in vivo in mice adopting the WHO protocol.

RESULTS

DrSL and DrI venom proteomes showed comparable major protein families, with phospholipases A2 (PLA2) being the most abundant (> 60% of total venom proteins) and diverse (six protein forms identified). Both venoms were highly procoagulant and lethal (intravenous median lethal dose in mice, LD50 = 0.24 and 0.32 µg/g, for DrSL and DrI, respectively), while lacking hemorrhagic and anticoagulant activities. VPAV was immunoreactive toward DrSL and DrI venoms, indicating conserved protein antigenicity in the venoms. The high molecular weight venom proteins were, however, more effectively immunorecognized than small ones. VPAV was able to neutralize the coagulopathic and lethal effects of the venoms moderately.

CONCLUSION

Considering that a large amount of venom can be injected by Russell's viper during envenomation, the potency of antivenom can be further improved for optimal neutralization and effective treatment. Region-specific venoms and key toxins may be incorporated into the immunization procedure during antivenom production.

Increased Mucosal Thrombin is Associated with Crohn's Disease and Causes Inflammatory Damage through Protease-activated Receptors Activation

BACKGROUND AND AIMS

Thrombin levels in the colon of Crohn's disease patients have recently been found to be elevated 100-fold compared with healthy controls. Our aim was to determine whether and how dysregulated thrombin activity could contribute to local tissue malfunctions associated with Crohn's disease.

METHODS

Thrombin activity was studied in tissues from Crohn's disease patients and healthy controls. Intracolonic administration of thrombin to wild-type or protease-activated receptor-deficient mice was used to assess the effects and mechanisms of local thrombin upregulation. Colitis was induced in rats and mice by the intracolonic administration of trinitrobenzene sulphonic acid.

RESULTS

Active forms of thrombin were increased in Crohn's disease patient tissues. Elevated thrombin expression and activity were associated with intestinal epithelial cells. Increased thrombin activity and expression were also a feature of experimental colitis in rats. Colonic exposure to doses of active thrombin comparable to what is found in inflammatory bowel disease tissues caused mucosal damage and tissue dysfunctions in mice, through a mechanism involving both protease-activated receptors -1 and -4. Intracolonic administration of the thrombin inhibitor dabigatran, as well as inhibition of protease-activated receptor-1, prevented trinitrobenzene sulphonic acid-induced colitis in rodent models.

CONCLUSIONS

Our data demonstrated that increased local thrombin activity, as it occurs in the colon of patients with inflammatory bowel disease, causes mucosal damage and inflammation. Colonic thrombin and protease-activated receptor-1 appear as possible mechanisms involved in mucosal damage and loss of function and therefore represent potential therapeutic targets for treating inflammatory bowel disease.

High throughput screening and identification of coagulopathic snake venom proteins and peptides using nanofractionation and proteomics approaches

Snakebite is a neglected tropical disease that results in a variety of systemic and local pathologies in envenomed victims and is responsible for around 138,000 deaths every year. Many snake venoms cause severe coagulopathy that makes victims vulnerable to suffering life-threating haemorrhage. The mechanisms of action of coagulopathic snake venom toxins are diverse and can result in both anticoagulant and procoagulant effects. However, because snake venoms consist of a mixture of numerous protein and peptide components, high throughput characterizations of specific target bioactives is challenging. In this study, we applied a combination of analytical and pharmacological methods to identify snake venom toxins from a wide diversity of snake species that perturb coagulation. To do so, we used a high-throughput screening approach consisting of a miniaturised plasma coagulation assay in combination with a venom nanofractionation approach. Twenty snake venoms were first separated using reversed-phase liquid chromatography, and a post-column split allowed a small fraction to be analyzed with mass spectrometry, while the larger fraction was collected and dispensed onto 384-well plates. After fraction collection, any solvent present in the wells was removed by means of freeze-drying, after which it was possible to perform a plasma coagulation assay in order to detect coagulopathic activity. Our results demonstrate that many snake venoms simultaneously contain both procoagulant and anticoagulant bioactives that contribute to coagulopathy. In-depth identification analysis from seven medically-important venoms, via mass spectrometry and nanoLC-MS/MS, revealed that phospholipase A2 toxins are frequently identified in anticoagulant venom fractions, while serine protease and metalloproteinase toxins are often associated with procoagulant bioactivities. The nanofractionation and proteomics approach applied herein seems likely to be a valuable tool for the rational development of next-generation snakebite treatments by facilitating the rapid identification and fractionation of coagulopathic toxins, thereby enabling specific targeting of these toxins by new therapeutics such as monoclonal antibodies and small molecule inhibitors.

Protease Activity Profiling of Snake Venoms Using High-Throughput Peptide Screening

Snake venom metalloproteinases (SVMPs) and snake venom serine proteinases (SVSPs) are among the most abundant enzymes in many snake venoms, particularly among viperids. These proteinases are responsible for some of the clinical manifestations classically seen in viperid envenomings, including hemorrhage, necrosis, and coagulopathies. The objective of this study was to investigate the enzymatic activities of these proteins using a high-throughput peptide library to screen for the proteinase targets of the venoms of five viperid (Echis carinatus, Bothrops asper, Daboia russelii, Bitis arietans, Bitis gabonica) and one elapid (Naja nigricollis) species of high medical importance. The proteinase activities of these venoms were each tested against 360 peptide substrates, yielding 2160 activity profiles. A nonlinear regression model that accurately described the observed enzymatic activities was fitted to the experimental data, allowing for the comparison of cleavage rates across species. In this study, previously unknown protein targets of snake venom proteinases were identified, potentially implicating novel human and animal proteins that may be involved in the pathophysiology of viper envenomings. The functional relevance of these targets was further evaluated and discussed. These new findings may contribute to our understanding of the clinical manifestations and underlying biochemical mechanisms of snakebite envenoming by viperid species.

Quantitative proteomic analysis and antivenom study revealing that neurotoxic phospholipase A2 enzymes, the major toxin class of Russell's viper venom from southern India, shows the least immuno-recognition and neutralization by commercial polyvalent antivenom

The proteome composition of Russell's viper venom (RVV) from southern India (SI) was investigated by 1D-SDS-PAGE of venom followed by tandem mass spectrometry analysis of protein bands. A total of 66 proteins belonging to 14 snake venom protein families were identified by LC-MS/MS analysis against Viperidae (taxid 8689) protein entries from the non-redundant NCBI database. Phospholipase A2 (43.25%) and snaclec (14.57%) represented the most abundant enzymatic and non-enzymatic proteins, respectively. SI RVV was characterized as containing a higher quantity of PLA2 and a lower amount of Kunitz-type serine protease inhibitors, in comparison to RVV from other regions of the Indian subcontinent. The enzymatic activities, pharmacological properties, and clinical manifestations of RV envenomation in SI were well correlated with its proteome composition; however, ATPase, ADPase, and hyaluronidase enzymes were not identified by LC-MS/MS analysis, owing to paucity of the existing database. Neurological symptoms exhibited by RV-bite patients in SI were correlated to the presence of abundant neurotoxic phospholipase A2 enzymes (15.66%) in SI RVV. Neutralization studies, immunological cross-reactivity, and antivenomics studies unequivocally demonstrated the poor recognition and lowest neutralization of PLA2 enzymes by commercial polyvalent antivenom, which is a major concern for the treatment of RV-envenomed patients in SI.

Proteomic Analysis and Immuno-Profiling of Eastern India Russell's Viper ( Daboia russelii) Venom: Correlation between RVV Composition and Clinical Manifestations Post RV Bite

The proteomes of Russell's viper venom (RVV) from Burdwan (RVV B) and Nadia (RVV N), the two districts of West Bengal, eastern India (EI), were investigated by gel-filtration chromatography (GFC) followed by tandem mass spectrometry of tryptic fragments of the fractions. A total of 73 and 69 proteins belonging to 15 snake venom protein families were identified in RVV B and RVV N, respectively, by MS/MS search against Viperidae (taxid 8689) protein entries of the nonredundant NCBI database. The minor differences in venom composition of both the EI RV were established unequivocally by their biochemical and pharmacological properties and by SDS-PAGE, gel filtration chromatography, and LC-MS/MS analyses. The composition of EI RVVs was well correlated with published reports on the pathophysiology of RV-envenomed patients from this part of the country. Venom-antivenom cross-reactivity determined by ELISA, Western blotting, and antivenomics approaches demonstrated poor recognition of low molecular mass (<20 kDa) RVV proteins by commercial polyvalent antivenoms, which was substantiated by neutralization of RVV enzymes by antivenom.

First report of the characterization of a snake venom apyrase (Ruviapyrase) from Indian Russell's viper (Daboia russelii) venom

A novel apyrase from Russell's viper venom (RVV) was purified and characterized, and it was named Ruviapyrase (Russell's viper apyrase). It is a high molecular weight (79.4 kDa) monomeric glycoprotein that contains 2.4% neutral sugars and 58.4% N-linked oligosaccharides and strongly binds to Concanavalin A. The LC-MS/MS analysis did not identify any protein in NCBI protein database, nevertheless some de novo sequences of Ruviapyrase showed putative conserved domain of apyrase superfamily. Ruviapyrase hydrolysed adenosine triphosphate (ATP) to a significantly greater extent (p < .05) as compared to adenosine diphosphate (ADP); however, it was devoid of 5'-nucleotidase and phosphodiesterase activities. The Km and Vmax values for Ruviapyrase towards ATP were 2.54 μM and 615 μM of Pi released min-1, respectively with a turnover number (Kcat) of 24,600 min-1. Spectrofluorometric analysis demonstrated interaction of Ruviapyrase with ATP and ADP at Kd values of 0.92 nM and 1.25 nM, respectively. Ruviapyrase did not show cytotoxicity against breast cancer (MCF-7) cells and haemolytic activity, it exhibited marginal anticoagulant and strong antiplatelet activity, and dose-dependently reversed the ADP-induced platelet aggregation. The catalytic activity and platelet deaggregation property of Ruviapyrase was significantly inhibited by EDTA, DTT and IAA, and neutralized by commercial monovalent and polyvalent antivenom.

Proteomics and antivenomics of Echis carinatus carinatus venom: Correlation with pharmacological properties and pathophysiology of envenomation

The proteome composition of Echis carinatus carinatus venom (ECV) from India was studied for the first time by tandem mass spectrometry analysis. A total of 90, 47, and 22 distinct enzymatic and non-enzymatic proteins belonging to 15, 10, and 6 snake venom protein families were identified in ECV by searching the ESI-LC-MS/MS data against non-redundant protein databases of Viperidae (taxid 8689), Echis (taxid 8699) and Echis carinatus (taxid 40353), respectively. However, analysis of MS/MS data against the Transcriptome Shotgun Assembly sequences (87 entries) of conger E. coloratus identified only 14 proteins in ECV. Snake venom metalloproteases and snaclecs, the most abundant enzymatic and non-enzymatic proteins, respectively in ECV account for defibrinogenation and the strong in vitro pro-coagulant activity. Further, glutaminyl cyclase, aspartic protease, aminopeptidase, phospholipase B, vascular endothelial growth factor, and nerve growth factor were reported for the first time in ECV. The proteome composition of ECV was well correlated with its biochemical and pharmacological properties and clinical manifestations observed in Echis envenomed patients. Neutralization of enzymes and pharmacological properties of ECV, and immuno-cross-reactivity studies unequivocally point to the poor recognition of <20 kDa ECV proteins, such as PLA₂, subunits of snaclec, and disintegrin by commercial polyvalent antivenom.

Unraveling the Proteome Composition and Immuno-profiling of Western India Russell's Viper Venom for In-Depth Understanding of Its Pharmacological Properties, Clinical Manifestations, and Effective Antivenom Treatment

The proteome composition of western India (WI) Russell's viper venom (RVV) was correlated with pharmacological properties and pathological manifestations of RV envenomation. Proteins in the 5-19 and 100-110 kDa mass ranges were the most predominate (∼35.1%) and least abundant (∼3.4%) components, respectively, of WI RVV. Non-reduced SDS-PAGE indicated the occurrence of multiple subunits, non-covalent oligomers, self-aggregation, and/or interactions among the RVV proteins. A total of 55 proteins belonging to 13 distinct snake venom families were unambiguously identified by ESI-LC-MS/MS analysis. Phospholipase A2 (32.5%) and Kunitz-type serine protease inhibitors (12.5%) represented the most abundant enzymatic and non-enzymatic proteins, respectively. However, ATPase, ADPase, and hyaluronidase, detected by enzyme assays, were not identified by proteomic analysis owing to limitations in protein database deposition. Several biochemical and pharmacological properties of WI RVV were also investigated. Neurological symptoms exhibited by some RV-bite patients in WI may be correlated to the presence of neurotoxic phospholipase A2 enzymes and Kunitz-type serine protease inhibitor complex in this venom. Monovalent antivenom was found to be better than polyvalent antivenom in immuno-recognition and neutralization of the tested pharmacological properties and enzyme activities of WI RVV; nevertheless, both antivenoms demonstrated poor cross-reactivity and neutralization of pharmacological activities shown by low-molecular-mass proteins (<18 kDa) of this venom.

Proteomic analysis to unravel the complex venom proteome of eastern India Naja naja: Correlation of venom composition with its biochemical and pharmacological properties

The complex venom proteome of the eastern India (EI) spectacled cobra (Naja naja) was analyzed using tandem mass spectrometry of cation-exchange venom fractions. About 75% of EI N. naja venom proteins were <18kDa and cationic at physiological pH of blood. SDS-PAGE (non-reduced) analysis indicated that in the native state venom proteins either interacted with each-other or self-aggregated resulting in the formation of higher molecular mass complexes. Proteomic analysis revealed that 43 enzymatic and non-enzymatic proteins in EI N. naja venom with a percent composition of about 28.4% and 71.6% respectively were distributed over 15 venom protein families. The three finger toxins (63.8%) and phospholipase A₂s (11.4%) were the most abundant families of non-enzymatic and enzymatic proteins, respectively. nanoLC-ESI-MS/MS analysis demonstrated the occurrence of acetylcholinesterase, phosphodiesterase, cholinesterase and snake venom serine proteases in N. naja venom previously not detected by proteomic analysis. ATPase, ADPase, hyaluronidase, TAME, and BAEE-esterase activities were detected by biochemical analysis; however, due to a limitation in the protein database depository they were not identified in EI N. naja venom by proteomic analysis. The proteome composition of EI N. naja venom was well correlated with its in vitro and in vivo pharmacological properties in experimental animals and envenomed human.

BIOLOGICAL SIGNIFICANCE

Proteomic analysis reveals the complex and diverse protein profile of EI N. naja venom which collectively contributes to the severe pathophysiological manifestation upon cobra envenomation. The study has also aided in comprehending the compositional variation in venom proteins of N. naja within the Indian sub-continent. In addition, this study has also identified several enzymes in EI N. naja venom which were previously uncharacterized by proteomic analysis of Naja venom.

A proteomic analysis of Pakistan Daboia russelii russelii venom and assessment of potency of Indian polyvalent and monovalent antivenom

To address the dearth of knowledge on the biochemical composition of Pakistan Russell's Viper (Daboia russelii russelii) venom (RVV), the venom proteome has been analyzed and several biochemical and pharmacological properties of the venom were investigated. SDS-PAGE (reduced) analysis indicated that proteins/peptides in the molecular mass range of ~56.0-105.0kDa, 31.6-51.0kDa, 15.6-30.0kDa, 9.0-14.2kDa and 5.6-7.2kDa contribute approximately 9.8%, 12.1%, 13.4%, 34.1% and 30.5%, respectively of Pakistan RVV. Proteomics analysis of gel-filtration peaks of RVV resulted in identification of 75 proteins/peptides which belong to 14 distinct snake venom protein families. Phospholipases A2 (32.8%), Kunitz type serine protease inhibitors (28.4%), and snake venom metalloproteases (21.8%) comprised the majority of Pakistan RVV proteins, while 11 additional families accounted for 6.5-0.2%. Occurrence of aminotransferase, endo-β-glycosidase, and disintegrins is reported for the first time in RVV. Several of RVV proteins/peptides share significant sequence homology across Viperidae subfamilies. Pakistan RVV was well recognized by both the polyvalent (PAV) and monovalent (MAV) antivenom manufactured in India; nonetheless, immunological cross-reactivity determined by ELISA and neutralization of pro-coagulant/anticoagulant activity of RVV and its fractions by MAV surpassed that of PAV.

BIOLOGICAL SIGNIFICANCE

The study establishes the proteome profile of the Pakistan RVV, thereby indicating the presence of diverse proteins and peptides that play a significant role in the pathophysiology of RVV bite. Further, the proteomic findings will contribute to understand the variation in venom composition owing to different geographical location and identification of pharmacologically important proteins in Pakistan RVV.

Proteomics and Metabolomics Analyses to Elucidate the Desulfurization Pathway of Chelatococcus sp

Desulfurization of dibenzothiophene (DBT) and alkylated DBT derivatives present in transport fuel through specific cleavage of carbon-sulfur (C-S) bonds by a newly isolated bacterium Chelatococcus sp. is reported for the first time. Gas chromatography-mass spectrometry (GC-MS) analysis of the products of DBT degradation by Chelatococcus sp. showed the transient formation of 2-hydroxybiphenyl (2-HBP) which was subsequently converted to 2-methoxybiphenyl (2-MBP) by methylation at the hydroxyl group of 2-HBP. The relative ratio of 2-HBP and 2-MBP formed after 96 h of bacterial growth was determined at 4:1 suggesting partial conversion of 2-HBP or rapid degradation of 2-MBP. Nevertheless, the enzyme involved in this conversion process remains to be identified. This production of 2-MBP rather than 2-HBP from DBT desulfurization has a significant metabolic advantage for enhancing the growth and sulfur utilization from DBT by Chelatococcus sp. and it also reduces the environmental pollution by 2-HBP. Furthermore, desulfurization of DBT derivatives such as 4-M-DBT and 4, 6-DM-DBT by Chelatococcus sp. resulted in formation of 2-hydroxy-3-methyl-biphenyl and 2-hydroxy -3, 3/- dimethyl-biphenyl, respectively as end product. The GC and X-ray fluorescence studies revealed that Chelatococcus sp. after 24 h of treatment at 37°C reduced the total sulfur content of diesel fuel by 12% by per gram resting cells, without compromising the quality of fuel. The LC-MS/MS analysis of tryptic digested intracellular proteins of Chelatococcus sp. when grown in DBT demonstrated the biosynthesis of 4S pathway desulfurizing enzymes viz. monoxygenases (DszC, DszA), desulfinase (DszB), and an NADH-dependent flavin reductase (DszD). Besides, several other intracellular proteins of Chelatococcus sp. having diverse biological functions were also identified by LC-MS/MS analysis. Many of these enzymes are directly involved with desulfurization process whereas the other enzymes/proteins support growth of bacteria at an expense of DBT. These combined results suggest that Chelatococcus sp. prefers sulfur-specific extended 4S pathway for deep-desulphurization which may have an advantage for its intended future application as a promising biodesulfurizing agent.

Carbon monoxide attenuates the effects of snake venoms containing metalloproteinases with fibrinogenase or thrombin-like activity on plasmatic coagulation

Carbon monoxide released from CORM-2 inhibitsCrotalus atroxsnake venom metalloproteinase mediated decreases in human plasma velocity of coagulation.

Structural and physico-chemical characterization of a dirhamnolipid biosurfactant purified from Pseudomonas aeruginosa: application of crude biosurfactant in enhanced oil recovery

The present study describes the structural characterization and biotechnological application of a dirhamnolipid biosurfactant produced byPseudomonas aeruginosastrain NBTU-01 isolated from a petroleum oil-contaminated soil sample.