Methionine-Containing Peptides: Avoiding Secondary Reactions in the Final Global Deprotection

The solid-phase synthesis of Met-containing peptides using a fluorenylmethoxycarbonyl (Fmoc)/tert-butyl (tBu) protection scheme is inevitably accompanied by two stubborn side reactions, namely, oxidation and S-alkylation (tert-butylation), which result in the formation of Met(O) and sulfonium salt impurities of the target peptide, respectively. These two reactions are acid-catalyzed, and they occur during the final trifluoroacetic (TFA)-based acidolytic cleavage step. Herein, we developed two new cleavage solutions that eradicate the oxidation and reduce S-alkylation. TFA-anisole-trimethylsilyl chloride (TMSCl)-Me₂S-triisopropylsilane (TIS) containing 1 mg of triphenyl phosphine per mL of solution was the optimal mixture for Cys-containing peptides, while for the remaining peptides, TIS was not required. Both cleavage solutions proved to be excellent when sensitive amino acids such as Cys and Trp were involved. TMSCl did not affect either of these sensitive amino acids. Reversing the sulfonium salt to free Met-containing peptide was achieved by heating the peptide at 40 °C for 24 h using 5% acetic acid.

Profitable Fischer Tropsch realization via CO2-CH4 reforming; an overview of nickel-promoter-support interactions

Environmental pollution, climate change, and fossil fuel extinction have aroused serious global interest in the search for alternative energy sources. The dry reforming of methane (DRM) could be a good technique to harness syngas, a starting material for the FT energy process from greenhouse gases. Noble metal DRM catalysts are effective for the syngas generation but costly. Therefore, they inevitably, must be replaced by their Ni-based contemporaries for economic reasons. However, coking remains a strong challenge that impedes the industrialization of the FT process. This article explains the secondary reactions that lead to the production of detrimental graphitic coke deposition on the surface of active nickel catalyst. The influence of nickel particle size, impact of extra surface oxygen species, interaction of Ni catalysts with metal oxide supports/promoters, and larger fraction of exposed nickel active sites were addressed in this review. Size of active metal determines the conversion, surface area, metal dispersion, surface reactions, interior diffusion effects, activity, and yield. The influence of oxygen vacancy and coke deposition on highly reported metal oxide supports/promoters (Al₂O₃, MgO and La₂O₃) was postulated after studying CIFs (crystallographic information files) obtained from the Crystallography open database (COD) on VESTA software. Thus, overcoming excessive coking by La₂O₃ promotion is strongly advised in light of the orientation of the crystal lattice characteristics and the metal-support interaction can be used to enhance activity and stability in hydrogen reforming systems.

A native mass spectrometry platform identifies HOP inhibitors that modulate the HSP90-HOP protein-protein interaction

Herein we describe a native mass spectromery protein-peptide model as a competent surrogate for the HOP-HSP90 protein-protein interaction (PPI), application of which led to the qualititive identification of two new peptides capable of in vitro PPI disruption. This proof of concept study offers a viable alternative for PPI inhibitor screening.

N-Butylpyrrolidinone for Solid-Phase Peptide Synthesis is Environmentally Friendlier and Synthetically Better than DMF

Solid-phase peptide synthesis (SPPS) is the method of choice for the preparation of peptides in both laboratory scale and large production. Although the methodology has been improved during the last decades allowing the achievement of long peptides and challenging sequences in good yields and purities, the process was not revised from an environmental point of view. One of the main problems in this regard is the large amount of solvents used, and therefore the tons of generated waste. Moreover, the solvent of choice for the SPPS is N,N-dimethylformamide (DMF), which is considered as reprotoxic; thus, there is an urgent necessity to replace it with safer solvents. The DMF substitution by a green solvent is not a trivial task, because it should solubilize all the reagents and byproducts involved in the process, and, in addition to facilitating the coupling of the different amino acids, it should not favor the formation of side-reactions compared with DMF. Herein, it was demonstrated that the use of the green solvent N-butylpyrrolidinone (NBP) as a replacement of DMF was beneficial in two well-documented side reactions in peptide synthesis, racemization and aspartimide formation. The use of NBP rendered a lower or equal level of racemization in the amino acids more prone to this side reaction than DMF, whilst the aspartimide formation was clearly lower when NBP was used as solvent. Our findings demonstrate that the use of a green solvent does not hamper the synthetic process and could even improve it, making it environmentally friendlier and synthetically better.

Biosecurity measures to reduce influenza infections in military barracks in Ghana

BACKGROUND

Military barracks in Ghana have backyard poultry populations but the methods used here involve low biosecurity measures and high risk zoonosis such as avian influenza A viruses or Newcastle disease. We assessed biosecurity measures intended to minimize the risk of influenza virus infection among troops and poultry keepers in military barracks.

FINDINGS

We educated troops and used a questionnaire to collect information on animal populations and handling practices from 168 individuals within 203 households in military barracks. Cloacal and tracheal samples were taken from 892 healthy domestic and domesticated wild birds, 91 sick birds and 6 water samples for analysis using molecular techniques for the detection of influenza A virus. Of the 1090 participants educated and 168 that responded to a questionnaire, 818 (75%) and 129 (76.8%) respectively have heard of pandemic avian influenza and the risks associated with its infection. Even though no evidence of the presence of avian influenza infection was found in the 985 birds sampled, only 19.5% of responders indicated they disinfect their coops regularly and 28% wash their hands after handling their birds. Vaccination of birds and use of personal protective clothing while handling the birds were low putting the people at risk.

CONCLUSION

Though some efforts have been made to improve biosecurity practices, interventions that help to protect the poultry flock from direct contact have to be practiced. Basic hygiene like washing of hands with soap and running water and regular cleaning of chicken coops are needed to prevent the spread of diseases among birds and between birds and humans.

Environmental sanitary interventions for preventing active trachoma

BACKGROUND

Trachoma is a major cause of avoidable blindness. It is responsible for about six million blind people worldwide, mostly in the poor communities of developing countries. One of the major strategies advocated for the control of the disease is the application of various environmental sanitary measures to such communities.

OBJECTIVES

To assess the evidence for the effectiveness of environmental sanitary measures on the prevalence of active trachoma in endemic areas.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials - CENTRAL in The Cochrane Library (Issue 2, 2007), MEDLINE (1966 to July 2007), EMBASE (1980 to July 2007), LILACS (July 2007), reference list of trials and the Science Citation Index. We also contacted agencies, experts and researchers in trachoma control.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled trials comparing any form of environmental hygiene measures with no measure. These hygiene measures included fly control, provision of water and health education. Participants in the trials were people normally resident in the trachoma endemic areas.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed the quality of trials. Study authors were contacted for additional information. Four trials met the inclusion criteria but meta-analysis was not conducted due to heterogeneity of the studies.

MAIN RESULTS

Two studies that assessed insecticide spray as a fly control measure found that trachoma is reduced by at least 55% to 61% with this measure compared to no intervention. However, another study did not find insecticide spray to be effective in reducing trachoma. One study found that another fly control measure, latrine provision, reduced trachoma by 29.5% compared to no intervention; this was, however, not statistically significantly different. Another study revealed that health education on personal and household hygiene reduced the incidence of trachoma such that the odds of reducing trachoma in the health education village was about twice that of the no intervention village. However, all the studies have some methodological concerns relating to concealment of allocation and non-consideration of clustering effect in data analysis.

AUTHORS' CONCLUSIONS

The role of insecticide spray as a fly control measure in reducing trachoma remains unclear. Latrine provision as a fly control measure has not demonstrated significant trachoma reduction. Health education may be effective in reducing trachoma. There is a dearth of data to determine the effectiveness of all aspects of environmental sanitation in the control of trachoma.

Environmental sanitary interventions for preventing active trachoma

BACKGROUND

Trachoma is the second or third major cause of blindness. It is responsible for about six million blind people worldwide, mostly in the poor communities of developing countries. One of the major strategies advocated for the control of the disease is the application of various environmental sanitary measures to such communities.

OBJECTIVES

To assess the evidence for the effectiveness of environmental sanitary measures on the prevalence of active trachoma in endemic areas.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials - CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) on The Cochrane Library (Issue 4, 2004), MEDLINE (1966 to January 2005), EMBASE (1980 to January 2005), LILACS (April 2004), the reference list of trials and the Science Citation Index. We also contacted agencies, experts and researchers in trachoma control.

SELECTION CRITERIA

This review included randomised and quasi-randomised controlled trials comparing any form of environmental hygiene measures with no measure. These hygienic measures included fly control, provision of water and health education. Participants in the trials were people normally resident in the trachoma endemic areas.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed the quality of trials. Study authors were contacted for additional information. Three trials met the inclusion criteria but meta-analysis was not conducted due to heterogeneity of the studies.

MAIN RESULTS

Two studies that assessed insecticide spray as a fly control measure found that trachoma is reduced by at least 55% to 61% with this measure compared to no intervention. One study found that another fly control measure, latrine provision, reduced trachoma by 29.5% compared to no intervention; this was, however, not statistically significantly different. Another study revealed that health education on personal and household hygiene reduced the incidence of trachoma such that the odds of reducing trachoma in the health education village was about twice that of the no intervention village. However, all the studies have some methodological concerns relating to concealment of allocation and non-consideration of clustering effect in data analysis.

AUTHORS' CONCLUSIONS

There is evidence that insecticide spray as a fly control measure reduces trachoma significantly. Latrine provision as a fly control measure has not demonstrated significant trachoma reduction. Health education may be effective in reducing trachoma. There is a dearth of data to determine the effectiveness of all aspects of environmental sanitation in the control of trachoma.