Action of Sulfating Agents on Proteins and Model Substances. II. Pyridine-chlorosulfonic Acid

Toward a framework for sulfoproteomics: Synthesis and characterization of sulfotyrosine‐containing peptides

“…Chemical sulfation of amino acids, peptides and proteins [83][84][85] has been studied even before Tyr sulfation was discovered as a naturally occurring modification by Bettelheim in 1954. 86 Most commonly, Tyr sulfation is achieved by treatment with concentrated sulfuric acid in the cold [43][44][45][87][88][89] or with a complex of sulfur trioxide with either pyridine 38,80,84,[89][90][91][92] or DMF.…”

Synthesis of Human [15-Norleucine]little-gastrin-II and Des-1-tryptophan-[12-norleucine]minigastrin-II

“…H-[Glu(OBu')]2-Ala-OH [9-1 Ib] prepared in stepwise manner via 7V-hydroxysuccinimide esters, and Z-[Glu(OBu f )]3-NHNH 2 produced by hydrazine treatment of the corresponding methy tester*. The azide coupling proceeded cleanly generating the desired hexapeptide derivative Z-[Glu(OBu f )] 5 -Ala-OH [6][7][8][9][10][11] in good overall yield as homogeneous product. Finally, the fragment III corresponding to sequence 1-5 was prepared following known procedures 122 !.…”

“…It is based on the condensation of the C-terminal hexapeptide derivative [12-17b] of the preceeding synthesis with the suitably protected heptapeptide corresponding to the little-gastrin sequence 5-11. The latter peptide derivative [5][6][7][8][9][10][11] was again prepared by assembly of two subfragments, i.e. H-[Glu(OBu f )] 2 -Ala-OH [9-1 Ib] and Boc-Leu-[Glu(OBu / )] 3 -NHNH 2 [5-8b] via the azide procedure.…”

Protease-catalyzed peptide bond formation: application to synthesis of the COOH-terminal octapeptide of cholecystokinin.

“…These failures can be explained by the finding that, in all cases, at least one of the reactants was degraded by the protease. IX was subjected to catalytic transfer hydrogenation to remove the benzyl ester groups from the aspartic acid side chains, after which the phenolic hydroxyl group ofthe tyrosine residue was esterified with the aid of a pyridine-sulfur trioxide complex (26). Removal of the N'-tert-butyloxycarbonyl group by using trifluoroacetic acid in the presence of thioanisole completed the synthesis.…”