Enantioselective binding and stable encapsulation of alpha-amino aids in a helical poly(L-glutamic acid)-shelled dendrimer in aqueous solutions.
A novel water-soluble peptide-shelled dendrimer containing a poly(L-glutamic acid) segment grafted on the third-generation poly(amido amine) dendrimer was successfully synthesized, and its secondary structural properties and interaction with alpha-amino acids (Trp, Phe, and Tyr) were revealed by spectroscopic measurements. In the lower pH region, this peptide-dendrimer adopted an alpha-helix conformation with almost 100 % helicity resulting from the three-dimensional aggregation of the segment. Interactions with alpha-amino acids proceeded with positive cooperativity on the basis of a Hill plot, and as a result, D isomers preferentially bound to the alpha-helical segments relative to L isomers. The bound alpha-amino acids were not released into the water phase but were transferred into the inner core of the dendrimer where they remained stable, even when a conformational change of the helix segment was caused by pH variation.
Higashi
Nobuyuki
N
Department of Molecular Science and Technology, Faculty of Engineering, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan. nhigashi@mail.doshisha.ac.jp
Koga
Tomoyuki
T
Niwa
Masazo
M
D000596:Amino Acids / Q000378:metabolism*; D002942:Circular Dichroism; D006863:Hydrogen-Ion Concentration; D011099:Polyglutamic Acid / Q000737:chemistry / Q000378:metabolism*; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D013237:Stereoisomerism; D014364:Tryptophan / Q000378:metabolism
D000596:Amino Acids; D011099:Polyglutamic Acid; D014364:Tryptophan