Peptide amidation by chemical protein engineering. A combination of enzymic and photochemical synthesis

Photolabile precursors of biological amides: synthesis and characterization of caged o-nitrobenzyl derivatives of glutamine, asparagine, glycinamide, and .gamma.-aminobutyramide

“…The time scale for the release of the amides from the photolabile o-nitrobenzyl protecting group was unknown and has now been investigated. The compounds are photolyzed by UV irradiation at 308 and 350 nm to release free amino acid amide and the presumed aromatic nitroso side product, with quantum yields in the range of 0.13 for the methyl derivative of glutamine (20) to 0.24 for the carboxy derivative of glutamine (21). Both pH and the -substituent of the o-nitrobenzyl protecting group affect the rate of the photolysis reaction, which is initiated by a single laser pulse at 308 nm and monitored by the optical absorbance decay time course of the transient oci-nitro anion intermediate.…”

“…The rate of disappearance of this intermediate, assumed to reflect the appearance of products, is influenced by pH and the -substituent attached to the benzylic carbon. For example, the rates for the -carboxyl (21) and -( 19) derivatives of glutamine increase by a factor of 50 as the pH is lowered from 11.5 to 5.5, whereas the rate for the -methyl derivative (20) shows a minimum at pH 9.5. The half lives of the oci-nitro intermediates of the -methyl, a-carboxyl, and -H derivatives of glutamine at pH 7.5 are 360, 720, and 1800 #ts, respectively.…”

A novel system for the preparation of orphan receptor ligand peptides

“…Other enzymatic methods for the preparation of recombinant α-amidated peptide using carboxypeptidase Y have been reported. 35,36 In this study, our recombinant and chemical cleavage methods make it possible to produce both the C-terminal acid and amide forms. This should be useful for checking to see whether the structures of C-termini are essential for the biological activities of peptides.…”

Peptide amidation by enzymatic transacylation and photolysis

“…Thr-Ala-fle-Gly-Val-Gly-Ala-Pro-Ala-Off (2112) (human calcitonin (22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32))-Ala-OH) with 2-nitrophenylglycinamide (5) using CPD-Y. 2-Nitrophenylglycinamide hydrobromide,lDMSO (60 mg, 0.17 mmol) was suspended in 5 mM EDTA (1 mL, pH -6.5) and pH was adjusted to 6.0 with 5 N NaOH.…”