3705-27-9Relevant articles and documents
Development of a dual fluorogenic and chromogenic dipeptidyl peptidase IV substrate
Ho, Nan-Hui,Weissleder, Ralph,Tung, Ching-Hsuan
, p. 2599 - 2602 (2006)
A new far-red dual fluorogenic and chromogenic substrate, 5-glycylprolylglycylprolyl-9-di-3-sulfonyl-propylaminobenza[a]phenoxazonium perchlorate (GPGP-2SBPO), was developed for dipeptidyl peptidase IV (DPP-IV) sensing. The glycylprolylglycylprolyl tetrapeptide was chosen as the recognition sequence due to its stability under physiological conditions. In contrast, the truncated substrate, GP-2SBPO, containing only a glycylprolyl peptide, is unstable. Proteolysis of GPGP-2SBPO was assayed by monitoring the absorbance and fluorescence signals from the released fluorochrome, 2SBPO, at 625 and 670 nm, respectively.
En Route to a Heterogeneous Catalytic Direct Peptide Bond Formation by Zr-Based Metal-Organic Framework Catalysts
Conic, Dragan,De Azambuja, Francisco,Harvey, Jeremy N.,Loosen, Alexandra,Parac-Vogt, Tatjana N.,Van Den Besselaar, Maxime
, p. 7647 - 7658 (2021/06/30)
Peptide bond formation is a challenging, environmentally and economically demanding transformation. Catalysis is key to circumvent current bottlenecks. To date, many homogeneous catalysts able to provide synthetically useful methods have been developed, while heterogeneous catalysts remain largely restricted to the studies addressing the prebiotic formation of peptides. Here, the catalytic activity of Zr6-based metal-organic frameworks (Zr-MOFs) toward peptide bond formation is investigated using dipeptide cyclization as a model reaction. Unlike previous catalysts, Zr-MOFs largely tolerate water, and reactions are carried out under ambient conditions. Notably, the catalyst is recyclable and no additives to activate the COOH group are necessary, which are common limitations of previous methods. In addition, a broad reaction scope tolerates substrates with bulky and Lewis basic groups. The reaction mechanism was assessed by detailed mechanistic and computational studies and features a Lewis acid activation of carboxylate groups by Zr centers toward amine addition in which an alkoxy ligand on adjacent Zr sites assists in lowering the barrier of key proton transfers. The proposed concepts were also used to study the formation of intermolecular peptide bond formation. While intrinsic challenges associated with the catalyst structure and water removal limit a more general intermolecular reaction scope under current conditions, the results suggest that further design of Zr-MOF catalysts could render these materials broadly useful as heterogeneous catalysts for this challenging transformation.
Water-Tolerant and Atom Economical Amide Bond Formation by Metal-Substituted Polyoxometalate Catalysts
De Azambuja, Francisco,Parac-Vogt, Tatjana N.
, p. 10245 - 10252 (2019/11/03)
A simple, safe, and inexpensive amide bond formation directly from nonactivated carboxylic acids and free amines is presented in this work. Readily available Zr(IV)- and Hf(IV)-substituted polyoxometalates (POM) are shown to be catalysts for the amide bond formation reaction under mild conditions, low catalyst loading, and without the use of water scavengers, dry solvents, additives for facilitating the amine attack, or specialized experimental setups commonly employed to remove water. Detailed mechanistic investigations revealed the key role of POM scaffolds which act as inorganic ligands to protect Zr(IV) and Hf(IV) Lewis acidic metals against hydrolysis and preserve their catalytic activity in amide bond formation reactions. The catalysts are compatible with a range of functional groups and heterocycles useful for medicinal, agrochemical, and material chemists. The robustness of the Lewis acid-POM complexes is further supported by the catalyst reuse without loss of activity. This prolific combination of Zr(IV)/Hf(IV) and POMs inaugurates a powerful class of catalysts for the amide bond formation, which overcomes key limitations of previously established Zr(IV)/Hf(IV) salts and boron-based catalysts.
