Heme coordination state determines the functional diversity of heme proteins. Using myoglobin as a model protein, we designed a distal hydrogen-bonding network by introducing both distal glutamic acid (Glu29) and histidine (His43) residues and regulated the heme into a bis-His coordination state with native ligands His64 and His93. This resembles the heme site in natural bis-His coordinated hem...

The dependence of amide proton chemical shifts on temperature is used as an indication of the hydrogen bonding properties in a protein. The amide proton temperature coefficients of the beta-helical antifreeze protein from Tenebrio molitor are examined to determine their hydrogen bonding state in solution. The temperature-dependent chemical shift behavior of the amides in T. molitor antifreeze p...

The title mol-ecule, C(9)H(8)N(2)O(2), is essentially planar. The crystal structure is stabilized by hydrogen bonding. An intra-molecular N-H⋯O hydrogen bond results in a six-membered ring. Each mol-ecule inter-acts with two others through N-H⋯O and C-H⋯O hydrogen bonding, resulting in the formation of nine-membered rings. These hydrogen bonds generate a two-dimensional polymeric network. There...

The title compound, C31H48O7·0.04CH3COOH, is a polyoxy-genated steroid obtained by selective chemical oxidation of 7-de-hydro-cholesteryl acetate. The asymmetric unit comprises three mol-ecules of the steroid (Z' = 3) and a mol-ecule of acetic acid which has occupancy factor 0.131 (5). The geometric parameters of the independent mol-ecules do not reveal significant differences. In one mol-ecule...

Helical polymers of isocyanotripeptides derived from alanine have been synthesized and their architectures studied in detail. The helical conformation of the polyisocyanotripeptides is stabilized by internal hydrogen-bonding arrays between the tripeptide side chains. The possibility of extending the well-defined hydrogen-bonded array, from dipeptide to tripeptide side chains, depends strongly o...

We characterize a highly unusual, charged NH-O hydrogen bond formed within esters of 8-(dimethylamino)naphthalen-1-ol in which an ammonium ion serves as an intramolecular hydrogen bond donor to spatially proximate ester ether oxygen atoms. Infrared spectroscopic analysis of the ester carbonyl frequencies demonstrates significant blue-shifting when ether hydrogen bonding is possible, in stark co...

In the title compound, C(10)H(12)N(2)O(5)S, one of the sulfonyl O atoms is hydrogen bonded to the amido N atom of an adjacent mol-ecule. There is also a weak hydrogen-bonding inter-action between the other sulfonyl O atom and the secondary amino N atom. In addition, the amido O atom is also hydrogen bonded to a carboxyl O atom. These hydrogen-bonding inter-actions give rise to a layer structure...

In the title compound, C(3)H(7)N(6) (+)·C(7)H(5)O(5) (-)·2H(2)O, the melaminium and benzoate ions are approximately planar (r.m.s. deviation of the non-hydrogen atoms is 0.093 Å) and there is a strong C(2) (2)(8) hydrogen-bonding embrace between them. The centre of symmetry generates a second acid-base pair which is bound to the first by a C(2) (2)(8) (N-H⋯N) embrace common between melamine mol...

Our goal was to gain a better understanding of the contribution of the burial of polar groups and their hydrogen bonds to the conformational stability of proteins. We measured the change in stability, Δ(ΔG), for a series of hydrogen bonding mutants in four proteins: villin headpiece subdomain (VHP) containing 36 residues, a surface protein from Borrelia burgdorferi (VlsE) containing 341 residue...