Abstract.Modified amino acids which can serve as precursors in the synthesis of tritium-labelled peptides were prepared and incorporated into biologically active peptides. Thus, p-iodophenylalanine was incorporated at position 4 of H-Met(0,)-Glu-His-Phe-D-Lys-Phe-OH (Org"2766) and in des-Tyr I-y-endorphin. As a second labelling site, the precursor of L-leucine, L-methallylglycine, was incorporated in both des-Tyrl-y-endorphin and the shorter des-enkephalin-y-endorphin. Finally, the lysine residue in Org 2766 (D-LYS) and des-enkephalin-y-endorphin (L-LYS) was replaced by its analogue 2,6-diamino-4-hexynoic acid. The precursor peptides were synthesized via the fragment condensation approach. With the exception of the methallylglycine-containing des-Tyr l-y-endorphin, in which partial desulfuri~ation of the methionine residue could not be prevented, these peptides could be converted by means of catalytic reduction into their respective parent compounds.
Synthesis of fragments of human P-lipotropin, P,-LPH be obtained (as calculated from eq. 1) which correlate with the experimental peroxidation rate constants for many aromatic molecules over a range of more than eight orders of magnitude. For reasons not yet fully understood, the most serious exceptions are 9, I0-dimethylanthracene and di benzan thracene. Given such limitations, we feel that the present data show that a simple FMO approach gives a satisfactory description of the reactivity of singlet oxygen towards many aromatic molecules. Furthermore, the applicability of the FMO model confirms that the endoperoxidation is adequately described by a [4x + 2x]-cycloaddition mechanism and that the progress of bond formation in the transition state shows little dependence on the reactivity of the aromatic substrate. It seems unlikely that the alternative stepwise pathway for the addition of singlet oxygen to diene-systems, proposed by Detour C.S. 19, can explain the correlation between reaction rates and FMO energies. Abstract. The synthesis of several peptides related to P-LPH-(62-77) but shortened from the Nterminal end, is described. In these syntheses use has been made of the classical fragment condensation approach.
The synthesis of β‐LPH‐(61–76) and β‐LPH‐(61–77) [i.e. α‐ and γ‐endorphin, respectively] by means of the fragment condensation approach is described.
Several of the fragments leading to these two endorphins were also obtained as pure, free peptides.
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Reaction ofsulphonium salt 8 with benzenethiolate giving 10a and 10bA solution of 8 (0.1 g, 0.28 mmol) in methanol (5 ml) was added to a stirred solution of benzenethiol (0.034 g, 0.31 mmol) and KOH (0.025 g, 0.45 mmol). After 2 h, water was added and work-up with ether followed by TLC afforded 95 mg (88%) of 10. 'H N M R : 6 3.10 (AB quartet, CH,S); 2.9-3.6 (m, CHS). (14)
Methyl I ,4-dio.uaspiro[4,5]decane-8-carba.~):late
Abstract. The synthesis of the hexadecapeptide des-I-tyrosine-y-endorphin, i.e. P-LPH-(62-77), by means of the fragment condensation approach, is described. According to De W i d and co-workers, this peptide, or a closely related one, may function as an endogenous neuroleptic.
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