As an aid in the selection of sites in a protein where a disulfide bond might be engineered, a computer program has been developed. The algorithm starts with the generation of C beta positions from the N, C alpha and C atom coordinates available from a three-dimensional model. A first set of residue pairs that might form a disulfide bond is selected on the basis of C beta-C beta distances betwe...

We have shown conclusively that during the hydrolysis of N-acylamino acid esters by proteases the substrate bond cleaved is the acyl-carbon-ethereal oxygen bond. This was done by hydrolyzing the ethyl esters in H2180-enriched water, isolating the ethanol formed, and determining the rsO:r60 ratio. The amount of ethanol-l80 found was that of natural abundance. This result supports what has hither...

In the title compound, C24H20N4, the azepine ring adopts a boat conformation and the dihedral angle between the benzene rings fused to it is 57.95 (8)°. The bond-angle sum at the azepine N atom is 346.6°, indicating a significant deviation from planarity. The triazole ring subtends a dihedral angle of 71.45 (10)° with the terminal phenyl group. A weak intra-molecular C-H⋯Na (a = azepine) inter-...

We have shown conclusively that during the hydrolysis of N-acylamino acid esters by proteases the substrate bond cleaved is the acyl-carbon-ethereal oxygen bond. This was done by hydrolyzing the ethyl esters in H2180-enriched water, isolating the ethanol formed, and determining the rsO:r60 ratio. The amount of ethanol-l80 found was that of natural abundance. This result supports what has hither...

The imidazopyridine fused ring in the title compound, C(20)H(16)BrN(3)O·H(2)O, is coplanar with the aromatic ring at the 2-position [dihedral angle = 5.2 (1)°]. In the five-membered imidazo portion, the C-N bond whose C atom is also connected to the pyridine N atom has predominantly double-bond character [1.334 (2) Å] whereas the C-N bond whose atom is connected to the pyridine C atom has predo...

The mol-ecule of the title compound, C(20)H(19)ClN(4)O(4)S, features a central pyrazole ring that possesses a benzene substituent, as well as a conjugated =C-C=C-C(meth-yl) substituent. The benzene ring is slightly twisted [dihedral angle = 7.7 (2)°] with respect to the five-membered ring; the mean plane of the zigzag =C-C=C-C fragment [torsion angle = 178.0 (4)°] is also slightly twisted [dihe...

The pyrrolo-pyridine system in the title compound, C(27)H(29)N(5)O(4)S, is oriented at a dihedral angle of 71.20 (5)° towards the phenyl ring of the tosyl residue and at a dihedral angle of 45.43 (4)° towards the benzyl group. The structure shows an intra-molecular N-H⋯O and a weak intra-molecular N-H⋯N hydrogen bond. The piperidine ring adopts a chair conformation, with the cis substituents di...

The penta-2,4-dien-1-one fragment of the title compound, C23H17ClOS, is twisted by 20.0 (3)°, as measured by the dihedral angle between the planes of the carbonyl group and its attached C atom and the distant C=C double bond and its attached C atom. The 4-chloro-phenyl group forms a dihedral angle of 4.0 (3)° with the adjacent carbonyl group. Conjugation between the phenyl ring and the C=C doub...

In the mol-ecule of the title compound, C(14)H(8)Cl(2)N(4)S, all the ring atoms in the pyrazolopyrimidine system are almost coplanar, the largest deviation from the mean plane being 0.027 (2) Å for a C atom. The conformation of the methyl-sulfanyl group is anti-periplanar, with a torsion angle of -176.7 (2)°. A weak inter-molecular C-H⋯N hydrogen bond and a Cl⋯N halogen bond [Cl⋯N = 3.196 (5) Å...