Specific blockade of muscle acetylcholine receptor by α-conotoxin MIA and MIB / 药学学报

The α-conotoxins are peptide toxins that are identified from the venom of marine cone snails and they hold outstanding potency on various subtypes of nicotinic acetylcholine receptors (nAChRs). nAChRs have an important role in regulating transmitter release, cell excitability, and neuronal integration, so nAChR dysfunctions have been involved in a variety of severe pathologies. Four types of α-3/5 conotoxins MI, MIA, MIB and MIC have been found from Conus magus. Among them, the activity and selectivity of MIA and MIB have not been well studied. In this study, four α-3/5 conotoxins MI, MIA, MIB and MIC were synthesized by solid peptide synthesis method, and the bioactivities of them were screened by double electrode voltage clamp electrophysiology. The results showed that MIA and MIB selectively inhibited muscle type acetylcholine receptors with IC50 values of 14.45 and 72.78 nmol·L-1, respectively, which are slightly weaker than MI and MIC. Molecular docking results have shown MIA and MIB interact with muscle-type nAChRs with similar mechanism. The reasons for activity differences may relate to the size of the N-terminal amino acids. Together, the conotoxins MIA and MIB may have the potential to develop as a tool for detect the function of muscle type nAChRs, as well as the diagnosis or treat of related diseases.

Preparation and performance research of target nmr contrast agent gd-dota-e-2 / 中国药学杂志

OBJECTIVE: To prepare Gd-DOTA-E-2 targeted contrast agent and evaluate its relaxation properties, cytotoxicity and targeting. METHODS: E-2 was synthesized by F-moc solid phase method, covalently bonded with chelating agent DOTA, meanwhile ultilizing chelating ligand Gd3+ to prepare MRI contrast agent Gd-DOTA-E-2. The structure was characterized by ESI-MS and NMR, and the properties were evaluated by relaxation properties, MTT and mouse MRI contrast assay. RESULTS: ESI-MS and NMR RESULTS showed that Gd-DOTA-E-2 was synthesized successfully, and its relaxation efficiency(k=9.551 mmol-1•L•s-1) is 1.84 times more efficient than a commercially available contrast agent of Gd-DOTA; MTT RESULTS showed that the toxicity of Gd-DOTA-E-2 cell is lower than that of Gd-DOTA; the experimental RESULTS in MRI angiography showed that Gd-DOTA-E-2 is possessing of targeting and can image clearly. CONCLUSION: Gd-DOTA-E-2 is a kind of MRI contrast agent with good stability, low cytotoxicity and targeted properties in vivo,which is valuable in research and application.

Solid-phase synthesis of Phakellistatin 13 based on photolabile protecting strategy / 国际药学研究杂志

Objective: Preparation of the Phakellistatin 13 by using of solid-phase peptide synthesis method and photolabile protecting group. Methods: By using of the DHP resin as the solid-phase supporter, a threonine derivative which was protected by the self-prepared photolabile protecting group was anchored to. The linear peptide was assembled via standard procedure with the threonine as the starting amino acid. After that, the photolabile protecting group was removed by UV irradiation, and the cyclization was completed while the peptide was still attached on the beads. The free cyclic peptide was then cut off by acid. Results: The photolabile 2-(2-nitrophenyl)-propanol (Npp-OH) was synthesized in one step from o-nitroethylbenzene. With the Npp group, the carboxyl group of threonine was blocked and Phakellistatin 13 was synthesized. The Phakellistatin 13 was identified by high resolution mass spectrometry, indicated that the strategy is quite available, which offer an efficient method for cyclic peptide synthesis. Conclusion: The Npp group had the advantages of easy prepared, high yields for protection and deprotection, be stable to the acidic and alkaline conditions, therefore it is an excellent third division protecting group. With this group, the cyclic peptide can be synthesized efficiently.

Solid-phase synthesis of Phakellistatin 13 based on photolabile protecting strategy / 国际药学研究杂志

Objective Preparation of the Phakellistatin 13 by using of solid-phase peptide synthesis method and photolabile protecting group. Methods By using of the DHP resin as the solid-phase supporter, a threonine derivative which was protected by the self-prepared photolabile protecting group was anchored to. The linear peptide was assembled via standard procedure with the threonine as the starting amino acid. After that, the photolabile protecting group was removed by UV irradiation, and the cyclization was completed while the peptide was still attached on the beads. The free cyclic peptide was then cut off by acid. Results The photolabile 2-(2-nitrophenyl)-propanol (Npp-OH) was synthesized in one step from o-nitroethylbenzene. With the Npp group, the carboxyl group of threonine was blocked and Phakellistatin 13 was synthesized. The Phakellistatin 13 was identified by high resolution mass spectrometry, indicated that the strategy is quite available, which offer an efficient method for cyclic peptide synthesis. Conclusion The Npp group had the advantages of easy prepared, high yields for protection and deprotection, be stable to the acidic and alkaline conditions, therefore it is an excellent third division protecting group. With this group, the cyclic peptide can be synthesized efficiently.

Solid-phase synthesis of the antifungal tetrapeptide from the culture of penicilli-um canescens / 药学实践杂志

Objective To synthesize the antifungal tetrapetide by solid-phase synthesis method .Methods The solid-phase peptide synthesis was chosen for getting the desired target tetrapeptide and its structure was confirmed by MS and 1 H NMR.Results The synthesis of the D-Phe-Val-D-Val-Tyr-OH was realized with yield of 47%.Conclusion The synthetic method was feasible and practical.The desired target tetrapeptide could be used for screening of antifungal activity .

Peptide synthesis: chemical or enzymatic

Peptides are molecules of paramount importance in the fields of health care and nutrition. Several technologies for their production are now available, among which chemical and enzymatic synthesis are especially relevant. The present review pretends to establish a non-biased appreciation of the advantages, potentials, drawbacks and limitations of both technologies. Chemical synthesis is thoroughly reviewed and their potentials and limitations assessed, focusing on the different strategies and challenges for large-scale synthesis. Then, the enzymatic synthesis of peptides with proteolytic enzymes is reviewed considering medium, biocatalyst and substrate engineering, and recent advances and challenges in the field are analyzed. Even though chemical synthesis is the most mature technology for peptide synthesis, lack of specificity and environmental burden are severe drawbacks that can in principle be successfully overcame by enzyme biocatalysis. However, productivity of enzymatic synthesis is lower, costs of biocatalysts are usually high and no protocols exist for its validation and scale-up, representing challenges that are being actively confronted by intense research and development in this area. The combination of chemical and enzymatic synthesis is probably the way to go, since the good properties of each technology can be synergistically used in the context of one process objective.

Improved solid phase synthesis of luteinizing hormone releasing hormone analogues using 9-fluorenylmethyloxycarbonyl amino acid active esters and catalytic transfer hydrogenation with minimal sidechain protection and their biological activities.

Using mainly 9-fluorenylmethyloxycarbonyl amino acid 2, 4, 5-trichlorophenyl esters in the presence of 1-hydroxybenzotriazole and the solid support p-alkoxybenzyl alcohol resin, synthesis of luteinizing hormone releasing hormone analogues was carried out with minimal side-chain protection. Catalytic transfer hydrogenation was employed for removal of NO2 and Z-groups from Arg and < Glu respectively avoiding the use of HF and this led to good yields. An aromatic, hydrophilic amino acid, D-(p-hydroxyphenyl) glycine was incorporated into luteinizing hormone releasing hormone molecule along with other modifications. The agonistic as well as antagonistic activities of all the peptides have been studied.