Coupling peptide

Many individual compound reports contain infrared spectral information, but there is only one in which detailed analysis appears. The 3-hydroxytriazolopyri-dine 125 used as a catalyst for peptide coupling (Section IV.J) has been studied in the solid and in solution, in association with a crystallographic study, and shown to exist as a dimer in solution (99MI1). 

A very considerable body of work has been published on the use of 3-hydrox-ytriazolopyridine (HOAt) 280 and its derivatives as peptide coupling catalysts,... 

Activated esters for use in peptide-coupling reactions were produced by photolysis of optically active chromium aminocarbenes with alcohols which are good leaving groups, such as phenol, pentafluorophenol, 2,4,5-trichlorophenol, and N-hydroxysuccinimide (Table 17) [ 109]. Since arylcarbenes bearing the op-... 

The first version of SPPS to be developed used the t-Boc group as the amino-protecting group. f-Boc can be cleaved with relatively mild acidic treatment and TFA is usually used. The original coupling reagents utilized for SPPS were carbodiimides. In addition to dicyclohexylcarbodiimide (DCCI), N, (V -diisopropylcarbodiimide (DIPCDI) is often used. The mechanism of peptide coupling by carbodiimides was... 

During the synthesis of glycopeptides, Pavia and coworkers had to confront the proposition that racemization of the amino acids may occur during either the peptide-coupling stage, or the glycosylation stage, or both. This presented a potential problem that had to be resolved. 

Twenty one rhena-/3-ketoimine derivatives of 14 different amino acids and one dipeptide have also been synthesized (37,38). The amino acid derivatives are prepared according to Eq. (3) in which the primary amine is an amino acid ester. A dipeptide derivative is formed via normal peptide coupling reactions, as shown in Eq. (4). In this reaction sequence, the ethyl... 

Figure 7.6 Peptides do not denature after baking (dry heat) or deparaffinization and antigen retrieval (wet heat). Peptide-coupled slides were treated as indicated on the Y-axis and then immunohistochemically stained. In this particular example, an ER peptide with an ER MAb was used. The resulting peptide spot intensity (mean pixel intensity on a 1-256 scale) was measured and is shown on the y-axis.The data represent the means and SD or triplicate measurements. The experiments on the left (solid bars) and the right (hatched bars) were conducted at different times and have no connection to one another. Adapted with permission from Sompuram et al.6...

A-Unsubstituted isoxazolidines such as 65 undergo facile decarboxylative peptide couplings with a-keto acids <06JA1452>. The use of water as solvent or cosolvent was particularly beneficial for the formation of amides in high yields. The methyl a-keto esters obtained could be saponified to the corresponding a-keto acids, and the (i-peptide chain could then be extended by reaction with another isoxazolidine. 

---