Zur selektiven acidolytischen Abspaltbarkeit der tert.-Butyloxycarbonyl-Gruppe

The methylsulfonylethyloxycarbonyl group, a new and versatile amino protective function

A new amino protecting group, the methylsulfonylethyloxycarbonyl (Msc) group, is described which combines well with other familiar groups (benzyloxycarbonyl, t-butyloxycarbonyl) in peptide syntheses. Its main characteristics are an extreme acid stability, a high base lability and a high polarity which enhances solubility in polar solvents including water. The group resists catalytic hydrogenolysis but does not poison the catalyst. It has good crystallizing properties. Application in peptide synthesis is exemplified in the synthesis of Msc-Phe-Arg-Trp-Gly-OMe.HCl. Deprotection of the masked tetrapeptide was accomplished within 5 sec with a 1.0 N solution of base (OH- and OCH3-). A reaction scheme for the cleavage of the group is suggested.

Practical syntheses of pyridinolines, important amino acidic biomarkers of collagen health

The paper reports some successful results on the first fully stereoselective total synthesis of the collagen cross-link pyridinolines. All stereogenic centers are stereoselectively introduced using Williams glycine template methodology, and oxazinones are used as a source of chirality and as easily removable protecting groups of the amino acidic functionalities during the assembly of the pyridinoline nucleus.

Biodegradable microspheres. 16. Synthesis of primaquine-peptide spacers for lysosomal release from starch microparticles

Classical procedures of peptide synthesis were applied to synthesize four groups of compounds, and analytical methods were developed for each of them. Two of the groups are tetrapeptide derivatives of the antileishmanial drug primaquine (PQ), with general structure NH2-X-Leu-Ala-Y-PQ. In the first group, Leu, Tyr, Lys, and Asp were used in the Y position, while X was Ala. In the second group, Ala, Tyr, Lys, and Asp were used in the X position, while Y was Leu. The derivatives are intended to be coupled, via their free alpha-amino group, to polyacryl starch microparticles, lysosomotropic drug carriers developed in our laboratory. Thus, a systematic study of the significance of the varying amino acid composition of the tetrapeptide spacer arm for the rate of lysosomal enzymatic release of PQ can be possible. A third group, comprising epsilon-aminocaproic acid-PQ derivatives which lack a free alpha-amino group, was synthesized. This was done to study the importance of enzymes, other than aminopeptidases, during lysosomal degradation of these derivatives. To allow HPLC analysis of the pattern of degradation of tetrapeptide-PQ derivatives, some shorter peptide-PQ derivatives (group four) were prepared as well.

Synthesis of cystine peptides 21-25/70-73 and 35-39/56-59 of the beta-subunit of human choriogonadotropin

Syntheses of two asymmetrical cystine peptides with the amino acid residues 21-25/70-73 and 35-39/56-59, based on the linear amino acid sequence and the disulfide bond assignment in the beta-subunit of human choriogonadotropin (hCG-beta), are described. S-trityl and S-acetamidomethyl peptide fragments of each cystine peptide were prepared in solution phase and were subjected to oxidation with I2/MeOH to form the disulfide bridge. The cystine peptides were characterized by their amino acid analyses and fast atom bombardment mass spectrometry. Immunological characterization by several homologous radioimmunoassay systems showed that peptide 21-25/70-73 had significant hCG, hCG-beta, and hLH activities while peptide 35-39/56-59 failed to reveal any immunoreactivity.

In search of new methods in peptide synthesis. A review of the last three decades

An attempt was made to discern ideas and trends in the development of peptide synthesis and to recognize general principles of the discipline. Introduction of efficient methods of activation and coupling during the early years of the reviewed period was followed by only moderate further improvements. Major advances were achieved by the discovery of novel methods of protection and by techniques of facilitation. Improvements in the methods of deblocking hold considerable promise and might bring significantly closer the goal of peptide synthesis: the direct preparation of homogeneous products.