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β‐Homoalanyl‐PNA: A Special Case of β‐Peptides with β‐Sheet‐Like Backbone Conformation; Organization in Higher Ordered Structures
Author(s) -
Diederichsen Ulf,
Schmitt Harald W.
Publication year - 1998
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(199805)1998:5<827::aid-ejoc827>3.0.co;2-b
Subject(s) - random hexamer , pentamer , chemistry , nucleobase , peptide nucleic acid , pairing , stacking , base pair , stereochemistry , side chain , crystallography , structural motif , peptide , dna , biochemistry , polymer , organic chemistry , physics , superconductivity , quantum mechanics
Although β‐homoalanyl peptide nucleic acid oligomers possess a β‐peptide backbone, they contain nucleobases in their side chains and are thus an interesting special case of β‐peptides. These nucleobases are mainly responsible for the formation of secondary structures through base pairing and stacking. We have investigated the pairing properties of β‐homoalanyl‐PNA oligomers using adenine and 7‐carbaadenine. Simple model studies indicate the existence of Watson‐Crick and Hoogsteen pairing planes as an intrinsic structural feature of purinyl β‐PNA. As a consequence, the adeninyl‐β‐PNA hexamer and pentamer form higher ordered structures and the 7‐carbaadenine‐β‐PNA hexamer, which lacks a Hoogsteen pairing site, pairs as a double strand. The synthesis of adeninyl and carbaadeninyl β‐nucleoamino acids and their oligomerization is described. Pairing mode and strand orientation were investigated through experiment and simple model studies. In the context of β‐peptides the β‐PNA oligomers for the most part tend to exist as double strands and prefer the extended β‐sheet‐like backbone conformation which provides an interesting structure motif in addition to the 3 1 ‐helix observed for β‐peptides.