Recent accomplishments, together with the traditional benefits of peptides (high biological activity, high specificity and low toxicity), have led pharmaceutical companies to re-focus their attention on peptide-based agents. Therefore, several serious diseases can be treated using the potential next generation of peptide drugs.
Linaclotide, a small 14-mer peptide highly rich in cysteines, is currently in phase III clinical trials for the treatment of gastrointestinal disorders. The challenge in the assembly of linaclotide consists of achieving the correct and clean folding of its three disulfide bridges. For this purpose, a number of regioselective, semiregioselective, and random strategies have been studied. In addition to selecting distinct protecting groups for the thiol function, their position in the sequence, the influence of the neighboring protecting groups, as well as the order in which the disulfides fold were studied. Here we describe an optimized solid-phase synthesis of linaclotide that should allow the production of this peptide in multigram amounts.
Two genes, aphE and orf, coding for putative Mr 29,000 and Mr 31,000, proteins respectively, were identified in the nucleotide sequence of a 2.8 kbp DNA segment cloned from Streptomyces griseus N2-3-11. The aphE gene expressed streptomycin (SM) resistance and a SM phosphorylating enzyme in S. lividans strains. The two genes were found to be in opposite direction and seemed to share a common region of transcription termination. The aphE gene shows significant homology to the aph gene, encoding aminoglycoside 3'-phosphotransferase, APH(3'), from the neomycin-producing S. fradiae. The enzymatic specificity of the aphE gene product was identified to be SM 3"-phosphotransferase, APH(3"). The primary structure of the APH(3") protein is closely related to the members of the APH(3') family of enzymes. However, the APH(3") enzyme did not detectably phosphorylate neomycin or kanamycin. There is only low similarity of the protein to the APH(6) group of SM phosphotransferases. An evolutionary relationship between antibiotic and protein kinases is proposed.
The Diels-Alder reaction of cis-5,6-diacetoxy-l,3-cyclohexadiene (l), which has a rneso configuration, with the chiral nitroso dienophile 2 occurs with induction of four asymmetric centers in very high optical yield (ee = 94%) and leads to the dihydro oxazine 3 (89%). The influence of the reaction temperature on the asymmetric induction was investigated and the absolute configuration of the product determined. Reductive cleavage of the N -0 bond of 3 presents a simple route to enantiomerically pure derivatives of (1R)-conduramine A1 (82%).Aminocyclitols are essential structure elements of many biologically active compounds. They have been found in aminoglycoside-aminocyclitol (AGAC) antibiotics'), in Amaryllidaceae alkaloids ' ' , and as ligands of cytostatic platinum complexes3'. In connection with our work on the mutasynthesis of new AGAC4' we are interested in the enantioand stereoselective synthesis of aminocyclitols. The key step in our synthetic pathway is the hetero Diels-Alder reaction of activated nitroso compounds with substituted cyclohexadienes ' I. Diacetoxydiene 1 was obtained by acetylation of cis-5,6-dihydroxy-l,3-cyclohexadiene with acetic anhydride and pyridine in nearly quantitative yield. This dihydroxy diene was prepared by Nakajima from tetrachlorodihydroxycyclohexane6); it is also available by microbial dioxygenase oxidation of benzene'). A biotechnological process using mutants of Pseudomonas putida was recently developed and allows the synthesis of the dihydroxydiene in multikilogram amounts *). HN: HCI)(' ova NO CHCLJEtOH &OAc a :The Diels-Alder reaction of 1 with the protected l-chloro-1-nitrosomannose') 2 yields the dihydro oxazine 3. The stereochemistry of 3 was determined from the 'H-NMR spectrum. The chemical shifts of the acetyl proton signals at 6 = 2.01 and 2.03 prove the endo position of the acetoxy groups. Signals of acetyl groups in exo positions, which are not shielded by the anisotropic effect of the double bond, would be expected at 6 = 2.15"). The chemical shifts of the 7-H (6 = 5.38) and 8-H (6 = 5.50) signals are characteristic for exo protons and confirm this assignment.For the investigation of the stereo-and enantioselectivity, we carried out a number of Diels-Alder reactions at different temperatures and isolated product 3 without recrystallization. After disappearance of the blue color of the nitroso compound, the reaction mixtures were extracted with water, and the product mixtures were lyophilized. The 'H-NMR spectra of the crude products showed that the reaction is stereoselective even at room temperature. The attack of the dienophile 2 obviously takes place only anti to the acetoxy substituents, from the sterically less shielded face of diene 1. The enantioselectivities of the Diels-Alder reactions were determined by establishing the enantiomeric purity of the dihydro oxazines using derivatization of the crude products with (S)-3,3,3-trifluoro-2-methoxy-2-phenylpropionyl chloride, separation of the diastereomeric amides by HPLC, and integration of the individual ...
This chapter describes the manufacturing process to a certain level for a possible oligonucleotide cargo and a peptide API in a multi-kilogram scale from a manufacture's point of view. In the concluding remarks, possible conjugation methods will be discussed from an industrial-scale perspective.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.