Analysis Of Reaction Products Research Articles

Production of ThreeO-Methhylated Esculetins withEscherichia coliExpressingO-Methyltransferase from Poplar

O-Methyltransferase, POMT-9 was expressed in Escherichia coli. HPLC analysis of reaction products revealed three peaks corresponding to isoscopoletin, scopoletin, and scoparone, and their structures were determined using NMR. Biotransformation of esculetin with E. coli expressing POMT-9 generated scopoletin, isoscopoletin, and scoparone at 30.3, 21, and 31 microM respectively. POMT-9 is the first O-methyltransferase that produces three different O-methylated products.

The 2000 Canine Distemper Epidemic in Caspian Seals (Phoca caspica): Pathology and Analysis of Contributory Factors

More than 10,000 Caspian seals (Phoca caspica) were reported dead in the Caspian Sea during spring and summer 2000. We performed necropsies and extensive laboratory analyses on 18 seals, as well as examination of the pattern of strandings and variation in weather in recent years, to identify the cause of mortality and potential contributory factors. The monthly stranding rate in 2000 was up to 2.8 times the historic mean. It was preceded by an unusually mild winter, as observed before in mass mortality events of pinnipeds. The primary diagnosis in 11 of 13 seals was canine distemper, characterized by broncho-interstitial pneumonia, lymphocytic necrosis and depletion in lymphoid organs, and the presence of typical intracytoplasmic inclusion bodies in multiple epithelia. Canine distemper virus infection was confirmed by phylogenetic analysis of reverse transcriptase-polymerase chain reaction products. Organochlorine and zinc concentrations in tissues of seals with canine distemper were comparable to those of Caspian seals in previous years. Concurrent bacterial infections that may have contributed to the mortality of the seals included Bordetella bronchiseptica (4/8 seals), Streptococcus phocae (3/8), Salmonella dublin (1/8), and S. choleraesuis (1/8). A newly identified bacterium, Corynebacterium caspium, was associated with balanoposthitis in one seal. Several infectious and parasitic organisms, including poxvirus, Atopobacter phocae, Eimeria- and Sarcocystis-like organisms, and Halarachne sp. were identified in Caspian seals for the first time.

Surface Plasmon Resonance Biosensors for Detection of PathogenicMicroorganisms: Strategies to Secure Food and Environmental Safety

This review describes the exploitation of exclusively optical surface plasmon resonance (SPR) biosensors for the direct and indirect detection of pathogenic microorganisms in food chains and the environment. Direct detection is, in most cases, facilitated by the use of defined monoclonal or polyclonal antibodies raised against (a part of) the target pathogenic microorganisms. The antibodies were immobilized to a solid phase of the sensor to capture the microbe from the sample. Alternatively, antibodies were used in an inhibition-like assay involving incubation with the target organism prior to analysis of nonbound antibodies. The free immunoglobins were screened on a sensor surface coated with either purified antigens or with Fc or Fab binding antibodies. Discussed examples of these approaches are the determination of Escherichia coli O1 57:H7, Salmonella spp., and Listeria monocytogenes. Another direct detection strategy involved SPR analysis of polymerase chain reaction products of Shiga toxin-2 genes reporting the presence of E. coli O157:H7 in human stool. Metabolic products have been exploited as biomarkers for the presence of a microbial agent, such as enterotoxin B and a virulence factor for the occurrence of Staphylococcus aureus and Streptococcus suis, respectively. Indirect detection, on the other hand, is performed by analysis of a humoral immune response of the infected animal or human. By immobilization of specific antigenic structures, infections with Herpes simplex and human immunodeficiency viruses, Salmonella and Treponema pallidum bacteria, and Schistosoma spp. parasites were revealed using human, avian, and porcine sera and avian eggs. Bound antibodies were easily isotyped using an SPR biosensor to reveal the infection history of the individual. Discussed studies show the recent recognition of the suitability of this type of instrument for (rapid) detection of health-threatening microbes to food and environmental microbial safety.

Photochemical reactions of thiols with organic nitrates — Oxygen atom transfer via a thionitrate

Nitroglycerin is an organic nitrate that has been used in the clinical treatment of angina for 130 years, yet important details of its mechanism of action remain unanswered. The biological activity of nitrates suggests that they are bioactivated to NO via a three-electron reduction. The involvement of free or bound protein thiols in this reduction has often been proposed. To examine the involvement of thiyl radicals in such a process, the photochemical generation of benzenethiyl radical from thiol and disulfide precursors was studied in the presence of isopropyl nitrate. Analysis of reaction products and kinetics led to the conclusion that photolysis of the nitrate to NO2dominated the observed photochemistry. Formation of sulfonothioate and NO as products, and trapping of NO2by 4-chlorophenol, indicated a mechanism involving oxygen atom transfer from N to S via a thionitrate intermediate. The results of the study did not indicate a rapid reaction between thiyl radical and organic nitrate. Despite weak nitrate absorption of light >300 nm and a relatively high BDE for homolysis to give NO2, the photochemistry under thiyl-generating conditions was driven by nitrate photolysis to NO2. A novel nitrate, containing a phenyl disulfanyl group linked to nitrate groups, did not undergo photolysis to NO2or generate sulfonothioate, but did yield NO. These observations suggest that reaction between thiyl radicals and nitrates leading to NO release is a viable pathway, but it is subservient to other competing reactions, such as photolysis, in the case of IPN, and reaction with thiolate, in the case of the novel nitrate.Key words: nitrate, photolysis, thiyl radical, nitrogen dioxide, nitric oxide.

Differentiation of Infectious Laryngotracheitis Virus Isolates by Restriction Fragment Length Polymorphic Analysis of Polymerase Chain Reaction Products Amplified from Multiple Genes

Infectious laryngotracheitis (ILT) has been identified in most countries around the world and remains a threat to the intensive poultry industry. Outbreaks of mild to moderate forms of ILT are common in commercial layer flocks, while sporadic outbreaks of ILT in broiler flocks have also been recognized as an emerging problem in several countries. Examination of viral isolates using restriction fragment length polymorphism of polymerase chain reaction (PCR-RFLP) from individual ILTV genes has suggested that some of these outbreaks were caused by vaccine strains. In this study, PCR-RFLP of a number of ILTV genes/genomic regions including gE, gG, TK, ICP4, ICP18.5, and open reading frame (ORF) B-TK was used to examine a number of historical and contemporary Australian ILTV isolates and vaccine strains. PCR-RFLP of gE using restriction endonuclease EaeI failed to distinguish between any of the isolates including the vaccine strains. PCR-RFLP of gG, TK, and ORFB-TK using restriction endonucleases MspI and FokI, respectively, divided all the isolates into two groups. PCR-RFLP of ICP18.5 and ICP4 using restriction endonuclease HaeIII separated the isolates into three different groups with some field isolates only able to be distinguished from vaccine strains by PCR-RFLP of ICP18.5. A combination of groupings including gG, TK, ICP4, ICP18.5, and ORFB-TK PCR-RFLP classified the ILTV isolates under investigation into five different groups with most isolates distinguishable from vaccine strains. Results from this study reveal that to achieve reliable identification of strains of ILTV, the examination of multiple gene regions will be required, and that most of the recent ILT outbreaks in Australia are not being caused by vaccine strains.

The (ADP-ribosyl)ation reaction in thermophilic bacteria

Species of Alicyclobacillus, Bacillus and Thermus genera were selected in order to study the possible presence of the (ADP-ribosyl)ation system. These bacteria are thermophilic, aerobic, and were isolated from different geothermal sources. Both activity and expression of (ADP-ribosyl)ating proteins were tested in cells at different growth phases, and evidence of an active system was obtained in all analyzed microorganisms, with comparable enzymatic levels. Immunochemical analyses with polyclonal antibodies against both eukaryotic anti-(ADP-ribose) transferase and anti-poly(ADP-ribose) polymerase revealed, for all tested organisms, an immunosignal localized in the range of molecular masses between 43–53 kD. Several proteins of various molecular masses were found as ADP-ribose acceptors. Reaction product analyses showed mono(ADP-ribose) to be the only synthesized compound.

Accuracy of DNA methylation pattern preservation by the Dnmt1 methyltransferase

DNA methyltransferase 1 (Dnmt1) has a central role in copying the pattern of DNA methylation after replication which is one manifestation of epigenetic inheritance. With oligonculeotide substrates we show that mouse Dnmt1 has a 30- to 40-fold preference for hemimethylated DNA that is almost lost after addition of fully methylated oligonucleotides. Using long hemimethylated DNA substrates that carry defined methylation patterns and bisulfite analysis of the methylation reaction products, we show a 15-fold preference for hemimethylated CG sites. Dnmt1 moves along the DNA in a random walk methylating hemimethylated substrates with high processivity (>50 sites are visited on average which corresponds to linear diffusion over 6000 bp). The frequency of skipping sites is very low (<0.3%) and there is no detectable flanking sequence preference. CGCTC sites tend to terminate the processive methylation of DNA by Dnmt1. Unmethylated DNA is modified non-processively with a preference for methylation at CCGG sites. We simulate the propagation of methylation patterns using a stochastic model with the specificity of Dnmt1 observed here and conclude that either methylation of several sites is required to propagate the methylation information over several cellular generations or additional epigenetic information must be used.

Molecular cloning, expression, and characterization of a flavonoid glycosyltransferase from Arabidopsis thaliana

Flavonoids are phytochemicals that owe their structural diversity to modifications such as methylation, hydroxylation, and glycosylation. The glycosylation of flavonoids affects solubility, stability and bioavailability and is mediated by the glycosyltransferase (GT) family 1. A GT from Arabidopsis thaliana ( AtGT-1) was cloned based on the homology with flavonoid GTs from other plants and classified as UGT73B2 based on the UDP-glycosyltransferase annotation system. Expression of AtGT-1 was detected higher in the flower and leaf than in root but not in the stem. The recombinant AtGT-1 protein expressed in E. coli was tested for activity on several substrates including apigenin, cyanidin, eriodictyol, isorhamnetin, kaempferol, luteolin, naringenin, and quercetin. Flavonols were better substrates for AtGT-1 than flavones or flavanones, and flavanones were better than flavones. Glycosylation of substrates preferentially occurred on the 3-hydroxyl group but the 7-hydroxyl group was glycosylated when the 3-hydroxy group was not available. The structures of kaempferol and naringenin reaction products were determined to be 3-glycosylated kaempferol and 7-glycosylated naringenin, respectively. Kaempferol was the most effective substrate tested. Based on HPLC, LC/MS, and NMR analysis of reaction products, along with the known flavonoid contents of Arabidopsis, AtGT-1 is likely to encode a kaempferol 3- O-UDP glucose transferase.

Molecular diversity and growth features of Flavobacterium columnare strains isolated in Finland

Columnaris disease caused by Flavobacterium columnare is a problem in fish farming worldwide. During the last 15 yr, outbreaks have started to emerge in Finland. Flavobacterium columnare Type Strain NCIMB 2248T and 30 Finnish F. columnare isolates were studied using analysis of 16S rDNA by restriction-fragment length polymorphism (16S RFLP), length heterogeneity analysis of polymerase chain reaction (LH-PCR) products, automated ribosomal intergenic spacer analysis (ARISA), and 16S rDNA sequence analysis. All isolates fell into RFLP Genomovar I and had the same length in the LH-PCR analysis. Based on ARISA, 8 genetically different strains were selected for further analyses. The growth of these strains under different temperatures, NaCl concentrations, and pH values was tested. The Finnish F. columnare strains did not grow at NaCl concentrations >0.1% or at pH values < or = 6.5, and they were susceptible to several antimicrobial agents, but not to Polymyxin B or neomycin. These findings may aid in development of methods for disease management at fish farms.

Capillary electrophoretic separation of inorganic sulfur–sulfide, polysulfides, and sulfur‐oxygen species

A CE protocol was developed for the identification and separation of inorganic polysulfides simultaneously with other inorganic sulfur-bearing species coexisting in aqueous hydrosulfide/sulfur solutions. The electrophoretic separation of thiosulfate, sulfate, hydrosulfide, sulfite, tetrathionate, and polysulfides was achieved at pH values between 8.2 and 12.2. The peaks attributed to the polysulfide species were strongly sensitive to pH. CE analysis of hydrosulfide/sulfur solutions at different pH values permitted possible identification of two forms of polysulfides: S4(2-) and S3(2-). Upon exposure to air at ambient temperature, thiosulfate was the main oxidation product of hydrosulfide/sulfur solutions mainly in the first 60 min, when hydrosulfide was rapidly consumed. Analysis of the oxidation reaction products provided retrospectively tentative evidence that the peaks separated and identified as tri- and tetrasulfide may be ascribed to polysulfides.

Automated sequence screening of the entire dystrophin cdna in Duchenne dystrophy: Point mutation detection

This is the first report of direct sequencing of the complete 11 kb coding sequence of the dystrophin gene affording high sensitivity for all types of mutations of both coding sequence and splicing. Direct automated capillary gel sequence analysis of dystrophin reverse-transcribed polymerase chain reaction (RT-PCR) products was carried out in 15 Duchenne muscular dystrophy (DMD) patient muscle biopsies (170,000 bp sequenced). We identified mutations in 67% of patients tested (10/15); including premature stop codons (n = 5) and small deletions/duplications (n = 5). Mutation-negative patients (n = 5) were also negative for promoter mutations. All were tested for the possibility of transcription abnormalities using quantitative multiplex fluorescence polymerase chain studies (QMF-PCR), however, equal ratios of mRNA transcripts were identified at the 5'and 3' regions, with mild reduction in overall quantity, suggesting that transcription abnormalities were less likely. We suggested that such patients might have a problem with the 3.5 kb 3' UTR, polyA site or undetected stop codons. It is also possible that splicing defects could result in addition of intron sequence which could lead to preferential amplification of low level residual normal transcript skipping.

The influence of pyrite pre-oxidation on gold recovery by cyanidation

The influence of pyrite pre-oxidation in alkaline solutions on gold recovery by cyanidation from Twin Creek refractory gold ore in which pyrite was identified as the major sulfide mineral has been investigated with the aid of electrochemical measurements, leaching experiments, and direct analysis of reaction products for selected residues. It was found that gold recovery by cyanidation in bottle roll experiments mainly depended on the extent of pyrite pre-oxidation. The rate of pyrite oxidation in alkaline solutions measured by electrochemical measurements, including chronoamperometry and linear sweep voltammetry, increased with an increase in pH, potential, and temperature. All alkaline reagents used for the electrochemical measurements, NaOH, NH 4OH, Na 2CO 3 and Ca(OH) 2, showed a similar effect on pyrite oxidation kinetics. However, the results of alkaline pre-oxidation for pyrite of the Twin Creek refractory gold ore suggested that NaOH and Na 2CO 3/Ca(OH) 2 were superior to Ca(OH) 2. Without pre-oxidation, cyanide leachable gold was found to be only 20% which could be increased to 70% under appropriate pre-oxidation conditions. At the same time, cyanide consumption decreased from 2.5 kg/t ore to 1.5 kg/t ore. Selected residues after pre-oxidation and cyanidation were examined by X-ray diffraction. Backscattered electron images of pyrite particles in these residues were taken. The reaction products at the surface of pyrite particles were found to be iron-, silicon-, and calcium-bearing compounds with variable amounts of sulfur as determined by X-ray energy dispersion analysis. Additionally, some mineral fines, such as aluminum and/or potassium-bearing minerals, were found to be present at the partially oxidized pyrite surface.

Fulminant B Hepatitis in a Hepatitis B Surface Antigen-Negative Patient after Rituximab Therapy for B-CLL.

Concerns about safety of rituximab in hepatitis B virus (HBV) carriers have risen at the light of reported cases of HBV reactivation following the administration of this agent. We recently observed a patient affected by B-cell Chronic Lymphocytic Leukemia (B-CLL) who developed this complication without any serological evidence of HBsAg expression.Case report: the patient, a 51 old year's male, was diagnosed as having B-CLL in November 1998 and followed until his death due to acute liver failure due to HBV reactivation of a mutant HBV strain in September 2004 (Table). At diagnosis of B-CLL no risk factors regarding liver diseases or viral infections were reported; serum HBsAg and HBeAg, antibodies against the B-core antigen (HBcAb), HBe (HBeAB), HBsAg (HBsAb), HCV, hepatitis A and Delta virus, Cytomegalovirus, and Epstein Barr virus were negative while HBcAb alone were positive. He presented stable disease until November 2001, when fludarabine was started because of progressive disease. A good partial response (GPR) was achieved so that he received four weekly standard doses (375 mg/m2) of rituximab as consolidation therapy (July 2002). A complete remission (CR) was obtained and he was then closely followed-up until about two years later (February 2004) when, for a disease recurrence, rituximab was given again. At that time all the above hepatitis markers remained unmodified. After four weekly standard doses of rituximab a GPR was recorded, and then six monthly courses (150 mg/m2) of the same agent were administered as maintenance therapy. In September 2004, being the patient in CR, he was admitted with acute hepatitis. HBV DNA strains (200,000 copies/mL) and HbcAb IgM were detected, whereas HbsAg-negative status persisted. The viral form was characterized as having D genotype and ayw3 serotype respectively.Sequence analysis of polymerase chain reaction (PCR) products amplified from the S region revealed 5 remarkable mutations in the major antigenic regions (C124Y, A128V, G130D, P135R and G145R). These mutations were associated with the lack of HbsAg production and were compatible with an escape of a rare HBV strain from the patient's own HbsAb. Despite treatment with lamivudine, the patient died of fulminant hepatic failure.Conclusion: our experience indicates that patients receiving rituximab who are negative for HBsAg but positive for anti-HBc are still at risk for reactivation of latent HBV and should be considered for HBV DNA testing and prophylaxis with lamivudine.Patient clinical featuresClinical featuresDiagnosis (November 1998)Disease Progression (November 2001)Disease Recurrence (February 2004)B Hepatitis onset (September 2004)Rai Clinical StageIIIII0CD38NegativeNegativeNegativeNegativeZap 70PositivePositivePositiveNegativeCD4/CD80.950.900.850.80Beta 2 microglobulin (mcg/L)1503182518441325Serum Ig level (gr/L)0,9800,7900,6600,620HBsAgNegativeNegativeNegativeNegativeHBsAbNegativeNegativeNegativeNegativeHBcAbPositivePositivePositivePositiveHBeAgNegatriveNegativeNegativePositiveHBeAbPositivePositivePositivePositiveHBV DNA*NANANA200.000/μL*D genotype, ayw3 serotype; C124Y, A128V, G130D, P135R and G145R mutations in the S region. NA:not available.

Tendon Healing In Vitro: bFGF Gene Transfer to Tenocytes by Adeno-Associated Viral Vectors Promotes Expression of Collagen Genes

Adeno-associated virus-mediated gene transfer is promising in the delivery of genes to tendons because this vector stimulates few adverse tissue reactions. Basic fibroblast growth factor (bFGF) promotes collagen production in healing tendons. We transferred the exogenous bFGF gene to proliferating tenocytes by adeno-associated viral (AAV) vectors and investigated its effects on the expression of the collagen genes in an in vitro tenocyte model. AAV2 vectors harboring the rat bFGF gene were constructed. Tenocytes were obtained from explant cultures of rat intrasynovial tendons and were distributed into 21 culture dishes and 8 wells. Tenocytes in 7 dishes were treated with AAV2 bFGF for 3 hours and then were cultured for 10 days. Tenocytes in 14 dishes (sham vector and nontreatment controls) did not receive the transgene. Efficiency of the gene transfer was evaluated by in situ beta-galactosidase staining in 8 wells after treatment with AAV2 lacZ. Expression of the target genes was assessed by reverse-transcription polymerase chain reactions with primers specifically amplifying the target genes. Expression of bFGF and type I and III collagen genes was determined by quantitative analysis of the polymerase chain reaction products. Positive beta-galactosidase staining confirmed the effectiveness of AAV2-mediated gene delivery to tenocytes. The level of expression of the bFGF gene was increased significantly after gene transfer. Levels of expression of type I and III collagen genes after transfer of the exogenous bFGF gene were increased significantly compared with those in the cells treated with sham vectors or in nontreatment controls. Delivery of exogenous bFGF gene to tenocytes can increase significantly the levels of expression of the bFGF and type I and III collagen genes. AAV2 vectors provide a novel method for delivering growth factor genes to tenocytes. These findings warrant future in vivo study of the delivery of genes pertinent to tendon healing through AAV2-based gene therapy to enhance repairs of injured flexor tendons.

An Enhanced Polymerase Chain Reaction Assay to Detect Pre- and Full Mutation Alleles of the Fragile X Mental Retardation 1 Gene

Several diagnostic strategies have been applied to the detection of FMR1 gene repeat expansions in fragile X syndrome. Here, we report a novel polymerase chain reaction-based strategy using the Expand Long Template PCR System (Roche Diagnostics, Mannheim, Germany) and the osmolyte betaine. Repeat expansions up to approximately 330 CGGs in males and up to at least approximately 160 CGGs in carrier women could be easily visualized on ethidium bromide agarose gels. We also demonstrated that fluorescence analysis of polymerase chain reaction products was a reliable tool to verify the presence of premutation and full mutation alleles both in males and in females. This technique, primarily designed to detect premutation alleles, can be used as a routine first screen for expanded FMR1 alleles.

Co-occurrence of West Nile Fever and circovirus infection in a goose flock in Hungary

The authors investigated an outbreak of West Nile Fever characterized by severe neurological symptoms and death in a flock of 3600 6-week-old geese. Ataxia, intermittent torticollis and opisthotonus, incoordination, rhythmic side-to-side movement of the head, wriggling of the neck and abnormal head position were features of the disease. Death occurred within 4 to 5 days after the clinical signs appeared. The average daily mortality was 5 to 15, reaching 14% (in total) over a period of 6 weeks. There were no consistent gross pathological lesions, but in a few cases yellowish-grey foci of 3 to 6 mm in diameter were observed on the surface or transection of the brain. Histopathology revealed perivascular lymphohistiocytic infiltration and glia cell proliferation in the brainstem, cerebellum, cortex and spinal cord as well as degeneration of neural fibres in the spinal cord. In addition to the lesions caused by the West Nile Virus in the brain, characteristics of circovirus infection such as lymphocyte depletion, vacuolization and basophilic intra-cytoplasmic inclusion bodies containing circovirus-like particles were seen by light and electron microscopy in the cloacal bursa. West Nile Virus infection was confirmed by reverse transcriptase-polymerase chain reaction amplification of virus-specific nucleic acid from tissue samples of the brain. Based on the nucleotide sequence analysis of the polymerase chain reaction products, 99% identity was found on the tested NS5 region with the IS-98 ST1 strain isolated from a stork in Israel in 1998, and with West Nile Virus stains emerging in the USA in 1999. Using an indirect fluorescent antibody test, high antibody titres against the virus were detected in the serum samples submitted from the affected flock. In selected sera this was confirmed by neutralization antibody test as well.

Surface-associated material from Porphyromonas gingivalis stimulates the release of nitric oxide by inducing expression of inducible nitric oxide synthase

The purpose of this study was to examine the effects of surface-associated material (SAM) from Porphyromonas gingivalis, a major cause of inflammatory periodontal disease, on the production of nitric oxide (NO) and expression of inducible nitric oxide synthase (iNOS) in the murine macrophage cell line RAW264.7. We also attempted to throw light on the signaling mechanisms involved in P. gingivalis SAM-induced NO production. SAM from P. gingivalis 381 was obtained by saline extraction. NO production was assayed by measuring the accumulation of nitrite in culture supernatants. Western blot analysis of iNOS and analysis of reverse transcription-polymerase chain reaction (RT-PCR) products were carried out. We found that P. gingivalis SAM can induce iNOS expression and stimulate the release of NO without additional stimuli and demonstrated an important role of the transcription factor NF-κB and microtubule polymerization in NO production. The production of NO required l-arginine, protein tyrosine kinase, and protein kinase C. The ability of P. gingivalis SAM to promote the production of NO may be important in the pathogenesis of inflammatory periodontal disease.

New hydrotreating NiMo catalysts supported on MCM-41 modified with phosphorus

A series of MCM-41 supports modified with phosphorus (0–5 wt.% P 2O 5) and their respective NiMo catalysts were prepared and characterized by N 2 physisorption, XRD, ammonia TPD, temperature programmed reduction (TPR), UV–vis diffuse reflectance spectroscopy (DRS), chemical analysis and HRTEM. It was shown that phosphorus insertion in the siliceous MCM-41 causes a deterioration of the textural characteristics and some loss in the periodicity of the MCM-41 pore structure. However, the acidity of MCM-41 material increases with P loading. XRD, DRS, TPR and HRTEM show that the characteristics of oxide and sulfided Mo and Ni species change with P incorporation in the MCM-41 support. Hydrodesulfurization (HDS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was used to evaluate the activity of the prepared catalysts. It was shown that the modification of MCM-41 with phosphorus results in high-performance NiMo catalysts especially for HDS of the most refractory dibenzothiophenes, such as 4,6-DMDBT. Catalysts of NiMo/P-MCM-41 series showed higher catalytic activity in 4,6-DMDBT HDS than the reference NiMo/Al 2O 3 counterpart. Maximum catalytic activity in this case was observed for the catalyst supported on MCM-41 with 1 wt.% P 2O 5. Reaction product analysis shows that phosphorus addition promotes hydrogenation pathway of HDS.

Photocatalytic degradation of hydrogen sulfide and in situ FT-IR analysis of reaction products on surface of TiO2

The photocatalytic oxidation of hydrogen sulfide at the gas/solid interface was investigated using TiO2 as the photocatalyst. A malodorous compound, hydrogen sulfide was removed via a photocatalytic process under ambient conditions. Hydrogen sulfide was oxidized to sulfate species on the surface of TiO2 without producing a noticeable gaseous intermediate, e.g., sulfur dioxide. The formation of sulfate species was confirmed by X-ray photoelectron spectroscopy (XPS). The surface chemistry of this photocatalytic oxidation was probed using two different types of in situ infrared (IR) spectroscopy techniques: diffuse reflectance IR spectroscopy (DRIFTS), and thin-film transmission IR spectroscopy. From the results obtained from DRIFT analysis, sulfate ions were accumulating proportionally with time on the surface of the catalyst during the course of the photocatalytic reaction. From further information gleaned from the transmission IR spectra (detected peaks at 1093 and 996cm−1), SO2− may be one of the predominant intermediates that appear over the time of this reaction. Although these results do not reveal the entire reaction pathway of the conversion of sulfides to sulfates, our results using these in situ FT-IR techniques have been valuable in confirming that the photocatalytic oxidation of hydrogen sulfide occurs on the surface of particulate TiO2.

Proteomic Method for the Quantification of Methionine Sulfoxide

Glycoxidation and lipoxidation reactions contribute to the chemical modification of proteins during the Maillard reaction. Reactive oxygen species, produced during the oxidation of sugars and lipids in these processes, irreversibly oxidize proteins. Methionine is particularly susceptible to oxidation, yielding the oxidation product methionine sulfoxide (MetSO). Here we describe a method for the analysis of MetSO using proteomic techniques. Using these techniques, we measured MetSO formation on the model protein RNase during aerobic incubations with glucose and arachidonate. We also evaluated the susceptibility of MetSO to reduction by NaBH4), a commonly used reductant in the analysis of Maillard reaction products.