Glycine’s pH-Dependent Polymorphism: A Perspective
from Self-Association in Solution
Weiwei Tang
Huaping Mo
Mingtao Zhang
Junbo Gong
Jingkang Wang
Tonglei Li
10.1021/acs.cgd.7b00969.s001
https://acs.figshare.com/articles/journal_contribution/Glycine_s_pH-Dependent_Polymorphism_A_Perspective_from_Self-Association_in_Solution/5406982
As
a simple amino acid, glycine (Gly)’s polymorphism is
pH-dependent. The α form is typically obtained from aqueous
solution between pH of 4 and 9, while the γ is produced at either
lower or higher pH. Formation of cyclic, hydrogen-bonded dimer in
water is debated as a possible cause for the formation of the α
form. To further understand the pH-dependent polymorphism, our current
study examined the self-association of Gly in aqueous solutions under
a wide range of pH, utilizing NMR, FTIR, and electronic calculation.
The results indicate that glycine molecules form open, not cyclic,
hydrogen-bonded dimers in water. It is revealed that the dimerization
becomes significant between pH of 4 and 8 but remains trivial at the
two pH extremes. The apparent connection between the pH-dependent
polymorphism and self-association in solution implies that formation
of the α form is driven by the dimerization, and moreover, charged
molecular species at the extreme pH facilitate stabilization of γ
nuclei.
2017-09-11 00:00:00
FTIR
pH-dependent polymorphism
formation
glycine molecules form
NMR
α form
solution