The IR absorption and 'H NMR analysis of the preferred conformation of monodisperse Z-(Aib),-OtBu (Z = (benzyloxy)carbonyl, OtBu = tert-butoxy, Aib = a-aminoisobutpic acid; n = 1-12) strongly indicates the formation of fully developed stable 310-helices for the higher (n = 8-12) homooligomers (pleionomers). This experimental study was performed in the solid state as well as in deuteriochloroform solution, in the latter case as a function of concentration, temperature, and addition of dimethyl sulfoxide and the free radical Tempo. A picture of the mode of self-association of the helical structures has also been obtained. A detailed theoretical study of Aib N-acetyl-"-methyl amide by conformational energy computations indicates that the fully extended structure is less stable than the helical structures, irrespective of the actual value of the N-C"-C' valence angle.
LINEAR OLIGOPEPTIDES .121. CONFORMATION OF PLEIONOMERS OF ALPHA-AMINOISOBUTYRIC-ACID / C., T., G., B., V., B., A., B., E., B., B., D.B., P., G., F., L., Pavone, V., C., P.. - In: MACROMOLECULES. - ISSN 0024-9297. - STAMPA. - 18:(1985), pp. 895-902.
LINEAR OLIGOPEPTIDES .121. CONFORMATION OF PLEIONOMERS OF ALPHA-AMINOISOBUTYRIC-ACID
PAVONE, VINCENZO;
1985
Abstract
The IR absorption and 'H NMR analysis of the preferred conformation of monodisperse Z-(Aib),-OtBu (Z = (benzyloxy)carbonyl, OtBu = tert-butoxy, Aib = a-aminoisobutpic acid; n = 1-12) strongly indicates the formation of fully developed stable 310-helices for the higher (n = 8-12) homooligomers (pleionomers). This experimental study was performed in the solid state as well as in deuteriochloroform solution, in the latter case as a function of concentration, temperature, and addition of dimethyl sulfoxide and the free radical Tempo. A picture of the mode of self-association of the helical structures has also been obtained. A detailed theoretical study of Aib N-acetyl-"-methyl amide by conformational energy computations indicates that the fully extended structure is less stable than the helical structures, irrespective of the actual value of the N-C"-C' valence angle.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
