2418-74-8Relevant articles and documents
Metabolic stability of peptidomimetics: N-methyl and aza heptapeptide analogs of a PKB/Akt inhibitor
Tal-Gan, Yftah,Freeman, Noam S.,Klein, Shoshana,Levitzki, Alexander,Gilon, Chaim
experimental part, p. 887 - 892 (2012/07/03)
Linear peptides suffer from poor pharmacokinetic and pharmacodynamic properties. Peptidomimetics are designed to overcome these pharmacological drawbacks while maintaining the biological effects of the parent peptides. Aza-peptides, in which an alpha carbon is replaced with nitrogen, are promising peptidomimetic analogs; however, little is known about the stability of these analogs toward enzymatic degradation. We performed systematic aza and N-methyl scans of a PKB/Akt inhibitor, PTR6154. We evaluated the stability of the aza-scan and N-methyl scan libraries toward enzymatic degradation by trypsin/chymotrypsin. Our results indicate that the modification site is important for metabolic stability and that aza-peptides have a more global effect than N-methylation, affecting cleavage sites distant from the modification site.
Bond cleavage reactions in solid aqueous carbohydrate solutions
Streefland, Lisette,Auffret, Anthony D.,Franks, Felix
, p. 843 - 849 (2007/10/03)
Purpose. To investigate chemical reactivity in water soluble glasses. Methods. Rates of bond cleavage reactions in freeze-dried and freeze- concentrated aqueous carbohydrate solutions were measured above and below the glass transition temperatures (T(g)). The kinetics of two reactions have been determined in formulations containing di- and polysaccharides: (1) fission of the Asp-Pro peptide bond in Physalaemin and Hamburger peptide by following the release of proline, using a ninhydrin based reaction and (2) the unimolecular dissociation of 2(4-nitrophenoxy) tetrahydropyran by following the release of the 4-nitrophenoxy anion. Results. The results show clearly that reaction occurs below the glass transition temperature, albeit at very reduced rates. No significant enhancement of the temperature dependence of the rate constant was observed near T(g). Different water soluble glasses provide different degrees of stability. The order of stabilisation was sucrose>Ficoll (low mol. weight)>Byco A ? Ficoll (high mol. weight)>dextran. The density of the matrix, and therefore the degrees of freedom of mobility of the reactant, is thought to be responsible for these differences. Conclusions. The storage of therapeutic agents, such as proteins, in glassy matrices below T(g) does not confer indefinite stability. When formulating products, notice should be taken of the differing stabilisation properties of excipients.