1. pH-Responsive Aminoproline-Containing Collagen Triple Helices
- Author
-
Christiane Siebler, Cedric Bergande, Jasmine Egli, Helma Wennemers, Boris Maryasin, Christian Ochsenfeld, and Roman S. Erdmann
- Subjects
Steric effects ,010405 organic chemistry ,Chemistry ,Stereochemistry ,Organic Chemistry ,Absolute configuration ,chemistry.chemical_element ,General Chemistry ,010402 general chemistry ,Ring (chemistry) ,01 natural sciences ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,Solvation shell ,Fluorine ,Thermal stability ,Ammonium ,Triple helix - Abstract
(4S)- and (4R)-configured aminoproline (Amp) residues were used as pH-responsive probes to tune the thermal stability of collagen triple helices in acidic and basic environments. The different steric and stereoelectronic properties of amino versus ammonium groups lead to a switch of the ring pucker of Amp upon changing the pH. The choice of the position of Amp within collagen model peptides (CMPs) as well as the absolute configuration at C(4) of the pH-responsive probe allows for tuning of the stability of Amp-containing collagen triple helices over a broad range. Comparative quantum chemical calculations on the steric and stereoelectronic effects of amino and ammonium groups versus fluorine, hydroxy, chlorine, and methyl substituents support the experimental findings. The research also shows that substitution of the naturally occurring hydroxy group in collagen by electron-withdrawing groups with a larger hydration shell than that of the hydroxy group is not tolerated.
- Published
- 2017