We previously suggested that proteins gain more stability from the burial and hydrogen bonding of polar groups than from the burial of nonpolar groups (Pace, C. N. (2001) Biochemistry 40, 310-313). To study this further, we prepared eight Thr-to-Val mutants of RNase Sa, four in which the Thr side chain is hydrogen-bonded and four in which it is not. We measured the stability of these mutants by...

In the title mol-ecule, C(14)H(10)ClNO, all non-H atoms are coplanar (r.m.s deviation = 0.0266 Å). In the crystal, symmetry-related mol-ecules are hydrogen bonded via inter-molecular O-H⋯O inter-actions, forming chains along the b axis.

Mol-ecules of the title compound, C7H10N2O4, systematic name 5-hy-droxy-5-propyl-pyrimidine-2,4,6(1H,3H,5H)-trione, form a hydrogen-bonded framework which is based on three independent hydrogen bonds, N-H⋯O(carbon-yl), N-H⋯O(hy-droxy) and O-H⋯O(carbon-yl). This framework has the topology of the 5-connected nov net. Each mol-ecule is linked to five other mol-ecules via six hydrogen bonds, and th...

In the title compound, C(4)H(8)N(5) (+)·Cl(-), a two-dimensional layer packing network is observed in which every chloride anion links three adjacent 2,4-diamino-6-methyl-1,3,5-triazin-1-ium cations by N-H⋯Cl hydrogen-bonding inter-actions, forming 12-membered and eight-membered hydrogen-bonded rings with graph-set motifs R(4) (4)(12) and R(3) (3)(8), respectively. In addition, N-H⋯N hydrogen b...

In the title compound, C(13)H(16)N(10)O(2)S·C(5)H(9)NO·H(2)O, the entire 1-methylpyrrolidin-2-one (NMP) mol-ecule is disordered over two sites with occupancies of 0.488 (5) and 0.512 (5). The six-membered triazine ring and the two five-membered pyrazole and thiadia-zole rings, together with the diazene (-N=N-) linkage are almost coplanar (r.m.s. deviation for the non-H atoms = 0.0256 Å) with me...

The equilibrium geometry and two measures (the dissociation energy in the complete basis set limit, De(CBS) intermolecular stretching force constant kσ) of strength non-covalent interaction each six Lewis acids M–X (M = Cu, Ag, Au) with nine simple bases B (B N2, CO, HCCH, CH2CH2, H2S, PH3, HCN, H2O, NH3) have been calculated at CCSD(T)/aug-cc-pVTZ level theory a systematic investigation coinag...

We propose a two sublattice model with a doubly periodic on-site potential to describe the proton transport in hydrogen-bonded quasi-one-dimensional networks. The discrete system is reduced to a continuum double Sine-Gordon equation for the protonic part plus a simple differential equation for the heavy ion part. Its two-component kink solitons correspond to the ionic and B j e m defects. The c...

Formation of C–H H–B dihydrogen bonded complexes of acetylene, fluoroacetylene, chloroacetylene, and cyanoacetylene with borane-trimethylamine were investigated with MP2 and B3LYP methods using 6-311++G(d,p) and aug-cc-pVDZ basis sets. The stabilization energies ranged from 6–20 kJ mol . NBO analysis predicts transfer of charge from r B–H bonding orbital to r* C–H anti-bonding orbital. It was a...