Pseudopeptides properties

Due to the good nucleophilic nature of sulfur, formation of new C—S bonds is relatively easy. This property has been used for intramolecular peptide cyclization 1 and was exploited for preparation of methylenethio ether surrogates, t >[CH2—S], initially as peptide gap inhibitors for blocking collagenase action. 2 These surrogates were later converted into sulfoxide and sulfone derivatives. This expansion of amide replacements compelled a more generalized nomenclature system for pseudopeptides (amides with one or more amide bond surrogates) and led directly to the psi-bracket convention. 1 ... 

While degradation studies have confirmed the improved stability of r t[CH2—S] pseudopeptides,]48] linear analogues with this modification have generally proven less active than their parent compounds. This property is attributable to the increased flexibility of the unit and its tendency to induce bent structures as seen in an X-ray structure of the dipeptide Boc-Alarjj[CH2-S]Phe-OH.t49]... 

Modification of the peptide backbone, including C -alkyl a-amino acids, a, 3-didehydro a-amino acids, and Na<->C and C° Ca cyclized a-amino acids and dipeptides, may influence the conformational properties of the resulting pseudopeptide molecules while preserving the mandatory side-chain substituents. 

Variations of the electrophiles employed in the NP+C strategy can furnish various dehydro pseudopeptides, a class of molecules that have been tested for their inhibitory properties but, in addition, as substrates for further functionalizatiOTi... 

This section is organized along the four fundamental properties of proteins. Hie imdertaken efibrts are summarized to elucidate how effectively these concepts can be transferred to synthetic polymer systems by integrating peptides (and their synthetic analogs, i.e., pseudopeptides) into synthetic polymers (translation of bioconcepts toward polymer sciences). 

The capability to define the monomer sequence in a monodisperse polymer block, for example, an oligonucleotide, a peptide, or a pseudopeptide segment, renders fine-tuning of polymer properties with monomer resolution feasible. Different monomeric building blocks can be seleaed from a... 

Sasl987 Sasaki, Y, Murphy, W.A., Heiman, M.L., Lance, V.A. and Coy, D.H., Solid-Phase Synthesis and Biological Properties of V [CH22NH] Pseudopeptide Analogues of a Highly Potent Somatostatin Octapeptide, J. Med. Chem., 30 (1987) 1162-1166. 

Peptide nucleic acids (PNA Fig. 10) are synthetic polynu-cleobase molecules which bind to DNA and RNA with high affinity and specificity. PNA was constructed with a charge-neutral, achiral, pseudopeptide backbone and is therefore chemically more closely related to peptides than to nucleic acids. Thus, PNAs, because of their backbone properties, show extremely good nucleic acid hybridization properties. In fact, PNA-DNA and PNA-RNA duplexes are, in general, thermally more stable than the corresponding DNA(RNA)-DNA(RNA) duplexes. 

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