Abstract:Peptidomimetics, the mimics of natural peptides are considered as promising therapeutics with potential applications in modern medicine. Among the various structural variants of peptidomimetics that have been designed and synthesized, the azapeptides serve as the interesting peptide backbone modifications owing to their diversified biological and pharmacokinetic properties. The aim of this review is to highlight the significance of azapeptide in enhancement of stability and bioavailability, represent the vario… Show more
“…As aza-peptides, they find use as inhibitors of serine and cysteine proteases due to their lower susceptibility to enzymatic hydrolysis in comparison to their peptide analogs and greater metabolic stability [ 95 , 96 ]. Moreover, the appropriate inclusion of an aza-amino acid in the synthetic peptide chain stabilizes its β-turns [ 97 ].…”
Section: Hydrazidesmentioning
confidence: 99%
“…Some hydrazides can be called aza-amino acids, that is, amino acids enriched with an additional amino group, simultaneously directly connected to the amino N atom and carbonyl C atom, that replace the α-CH moiety. If said aza-amino acid is a part of a poly-chain of at least 10 members, it forms the aza-peptide ( Figure 17 and Figure 18 ) [ 95 ].…”
Schiff bases are a vast group of compounds characterized by the presence of a double bond linking carbon and nitrogen atoms, the versatility of which is generated in the many ways to combine a variety of alkyl or aryl substituents. Compounds of this type are both found in nature and synthesized in the laboratory. For years, Schiff bases have been greatly inspiring to many chemists and biochemists. In this article, we attempt to present a new take on this group of compounds, underlining of the importance of various types of Schiff bases. Among the different types of compounds that can be classified as Schiff bases, we chose hydrazides, dihydrazides, hydrazones and mixed derivatives such as hydrazide–hydrazones. For these compounds, we presented the elements of their structure that allow them to be classified as Schiff bases. While hydrazones are typical examples of Schiff bases, including hydrazides among them may be surprising for some. In their case, this is possible due to the amide-iminol tautomerism. The carbon–nitrogen double bond present in the iminol tautomer is a typical element found in Schiff bases. In addition to the characteristics of the structure of these selected derivatives, and sometimes their classification, we presented selected literature items which, in our opinion, represent their importance in various fields well.
“…As aza-peptides, they find use as inhibitors of serine and cysteine proteases due to their lower susceptibility to enzymatic hydrolysis in comparison to their peptide analogs and greater metabolic stability [ 95 , 96 ]. Moreover, the appropriate inclusion of an aza-amino acid in the synthetic peptide chain stabilizes its β-turns [ 97 ].…”
Section: Hydrazidesmentioning
confidence: 99%
“…Some hydrazides can be called aza-amino acids, that is, amino acids enriched with an additional amino group, simultaneously directly connected to the amino N atom and carbonyl C atom, that replace the α-CH moiety. If said aza-amino acid is a part of a poly-chain of at least 10 members, it forms the aza-peptide ( Figure 17 and Figure 18 ) [ 95 ].…”
Schiff bases are a vast group of compounds characterized by the presence of a double bond linking carbon and nitrogen atoms, the versatility of which is generated in the many ways to combine a variety of alkyl or aryl substituents. Compounds of this type are both found in nature and synthesized in the laboratory. For years, Schiff bases have been greatly inspiring to many chemists and biochemists. In this article, we attempt to present a new take on this group of compounds, underlining of the importance of various types of Schiff bases. Among the different types of compounds that can be classified as Schiff bases, we chose hydrazides, dihydrazides, hydrazones and mixed derivatives such as hydrazide–hydrazones. For these compounds, we presented the elements of their structure that allow them to be classified as Schiff bases. While hydrazones are typical examples of Schiff bases, including hydrazides among them may be surprising for some. In their case, this is possible due to the amide-iminol tautomerism. The carbon–nitrogen double bond present in the iminol tautomer is a typical element found in Schiff bases. In addition to the characteristics of the structure of these selected derivatives, and sometimes their classification, we presented selected literature items which, in our opinion, represent their importance in various fields well.
“…1.). This replacement yields alkylcarbazic acids (II), also known as a-aza amino acids [7,8], and their inclusion in the peptide chain yields azapeptides.…”
The replacement of the α-carbon atom in an α-amino acid structure by a nitrogen atom yields alkylcarbazic acids, also known as α-aza amino acids. Although the topology of α-amino acids and α-aza amino acids is similar, their chemical and stereochemical properties are significantly different. For this reason, the application of the common solid-phase peptide synthesis (SPPS) protocol cannot be used for aza-peptide bond synthesis without changes. On the other hand, the aza-peptide bond is more stable than the common peptide bond, therefore these compounds are very attractive targets for drug design. In this review, we summarize data on aza-peptide bond chemistry, with implications for the improvement of aza-peptide chemical synthesis.
“…This seemingly small structural change can have substantial effects on peptide structure and electronics such as increasing intrinsic chemical stability and resistance towards biodegradation7 and improving collagen stability and self-assembly 4b,c. These properties have led to the pursuit of aza-peptides as promising candidates for therapeutic applications,8 which generated a wave of new solid-phase synthetic methods9 and fundamental studies 10. Collagen peptides containing non-natural amino acid substitutions that do not disturb the overall collagen topology would be useful biological tools to probe the collagen interactome 3 b…”
Chenoweth and co-workers provide an atomic resolution crystal structure and computational analysis illustrating that aza-proline mimics l-proline stereochemistry in collagen.
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