Experimental and Computational Modeling of H-Bonded Arginine-Tyrosine Groupings in Aprotic Environments.

ABSTRACT: H-bonds between neutral tyrosine and arginine in nonpolar environments are modeled by small-molecule phenol/guanidine complexes. From the temperature and concentration dependence of UV spectra, a value of ΔH° = -74 ± 4 kJ mol^-1 is deduced for the formation of H-bonded p-cresol/dodecylguanidine in hexane. ΔE = -71 kJ mol^-1 is computed with density functional theory (in vacuo). In dimethyl sulfoxide or crystals, (p-phenolyl)alkylguanidines form head-to-tail homodimers with two strong H-bonding interactions, as evidenced by UV, IR, and NMR spectral shifts, strong IR continuum absorbance bands, and short O···N distances in X-ray crystal structures. Phenol/alkylguanidine H-bonded complexes consist of polarizable rapidly interconverting tautomers

SUBMITTER: Banyikwa AT 

PROVIDER: S-EPMC6644469 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature