Protected peptide fragments cleavage from resin

Protocols. Cleavage of protected peptide fragments from 2-chlorotrityl resin... 

Peptide hydrazides are readily converted to the corresponding acylazides by the action of alkyl nitrites and under appropriate conditions these activated species can be among the least susceptible to racemization. Cleavage of the peptide from the resin as the hydrazide is most useful with protected molecules, which can subsequently be used in fragment condensation to assemble longer peptides. 

Cleavage of the peptide from the resin by trans-esterification can be achieved readily with most alcohols. The resultant C-terminal-protected molecules can be used in fragment condensation to assemble longer peptides. The protocol described here involves cleavage with methanol in the presence of a tertiary base. The methyl ester produced can subsequently be removed by saponification. 

Acidolytic cleavage is also free from racemization. However, the danger of racemization exists when the resin-peptide bond is cleaved by ammonolysis or base-catalyzed transesterification. These cleavage reactions are sometimes used with the modified resin supports or when the protected fragment is desired for fragment condensation. 

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