ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Poly(Nδ-carbobenzoxy, Nδ-benzyl-L-ornithine) (PCBLO) was prepared by the standard NCA method. PCBLO was converted into poly(Nδ-benzyl-L-ornithine) (PBLO) through decarbobenzoxylation with hydrogen bromide. The monomer Nδ-benzyl-L-ornithine was synthesized by reacting L-ornithine with benzaldehyde, followed by hydrogenation. The conformation of the two polypeptides was studied by optical rotatory dispersion and circular dichroism. PCBLO forms a right-handed helix in helix-promoting solvents. In mixed solvents of chloroform and dichloroacetic acid (DCA) it undergoes a sharp helix-coil transition at 12% (v/v) DCA at 25°C, as compared with 36% for poly(Nδ-carbobenzoxy-L-ornithine) (PCLO). Like PCLO, the helix-coil transition is “inverse,” that is, high temperature favors the helical form. PBLO is soluble in water at pH below 7 and has a “coiled” conformation. In 88% (v/v) 1-propanol above pH (apparent) 9.6 it is completely helical. In 50% 1-propanol the transition pH (apparent) is about 7.4; this compares with a pHtr of about 10 for poly-L-ornithine in the same solvent.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.1974.360130605
