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发布于:2019-1-18 01:15:48  访问:51 次 回复:0 篇
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El compound in water.Molecular Interpretation of Preferential Interactions of Urea
Hydrogen bonding of urea to amide oxygens on side S55746 site chains of Poly(N-isopropylacrylamide) (PNIPAM) in water has been quantified not too long ago by FTIR (28). S3). Carboxylate O: Modest accumulation of urea inside the vicinity of carboxylate O (K p ?1.13) indicates most simply that formation of a hydrogen bond donated by a urea-amide N to a carboxylate O, releasing water, is favored in comparison to hydrogen bonds of both groups to water. GB is identified to become at the very least as strongly excluded from carboxylate O as from amide O (K p ?0.24), simply because GB lacks any hydrogen bond donor group to compete with water to interact with either anionic or amide O. These modest K p values indicate that hydrogen bonds in between the amide N of urea, acting as donor or Ametycine site acceptor, and an amide or cationic N on a further molecule have to be fairly unf.El compound in water.Molecular Interpretation of Preferential Interactions of Urea and GB with Functional Groups of Proteins. Urea, like water, has multipleFig. two. Plot of predicted vs. observed values of 23 RT for interactions of urea with model compounds (see Table S1). Line represents equality of predicted and observed values.Guinn et al.PNAS October 11,vol.no.CHEMISTRYhydrogen bond donors and acceptors, but glycine betaine has no hydrogen bond donor capability. This key distinction is sufficient to clarify the differences in K p values (Table 1) for interactions of urea and GB with N and O groups. Amide O: Moderately PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/25564241 robust accumulation of urea inside the vicinity of any amide O group (K p ?1.28) indicates most just that formation of a hydrogen bond donated by a urea-amide -NH to an amide O, collectively using a water ater hydrogen bond, is favored as compared to hydrogen bonds with the urea-amide -NH and the amide O to water. The urea-amide O interaction is one PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/26061106 of the two most favorable preferential interactions of urea using the functional groups of proteins. In stark contrast, GB is very excluded from amide O (K p ?0.24), presumably for the reason that GB lacks a hydrogen bond donor group and so cannot compete with water to interact with amide O. The free energy of transfer with the peptide backbone from water to an osmolyte remedy (1 M) is found to decrease strongly and about linearly because the fraction of polar surface from the osmolyte increases, with trimethylamine N-oxide (TMAO) and GB at the nonpolar and unfavorable end of your series, and urea and GuHCl in the polar and favorable finish (27). Mainly because amide O is definitely the principal contributor to peptide backbone surface, the skills of those solutes to compete withwater to hydrogen bond to amide O are likely the determinant of their place within this series; TMAO, like GB, can‘t compete with water to interact with amide O, whereas GuH?interacts a great deal additional favorably with amide O (K p ?two.eight) (17) than does urea (K p ?1.28). Hydrogen bonding of urea to amide oxygens on side chains of Poly(N-isopropylacrylamide) (PNIPAM) in water has been quantified recently by FTIR (28).
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