Several substrate-like epoxides were found to act as specific and irreversible inactivators of pepsin. Of these, 1,2-epoxy-3-(p-nitrophenoxy) propane (EPNP) was the most potent. When EPNP reacted with pepsin, all enzyme activity was lost. Two molecules of EPNP were found to be covalently bound to each molecule of completely inactivated enzyme. In this reaction, two carboxyl groups of the enzyme...

The title compound, C(9)H(4)F(6)O(2), contains two mol-ecules in the asymmetric unit, one of which exhibits disorder in both of its trifluoro-methyl groups. The dihedral angles between the benzene ring and the carboxyl group are 71.5 (2) and 99.3 (2)° in the two independent mol-ecules. The compound exhibits a catemeric structure resulting from inter-molecular O-H⋯O hydrogen bonding between the ...

In the centrosymmetric binuclear title complex, [La(2)(C(9)H(9)O(3))(6)(C(12)H(8)N(2))(2)], the two La(III) ions are linked by four 2-phen-oxy-propionate (L) groups in bi- and tridentate bridging modes. Each La(III) ion is nine-coordinated by one 1,10-phenanthroline mol-ecule, one bidentate chelating carboxyl-ate group and four bridging carboxyl-ate groups in a distorted LaN(2)O(7) monocapped s...

Morphological changes and the content of free carboxyl groups in bovine collagen (type I) film under the influence of trypsin, hydrochloric acid (HCl) and ethylenediaminetetraacetic acid (EDTA) were studied. Incubation with trypsin and HCl was found to cause some delamination of the film and the appearance of some low-density spots. Incubation with EDTA did not cause any morphological changes. ...

The title compound, C(16)H(12)O(6), is a common impurity of ortho-acetyl-salicylic acid (aspirin). The benzene rings form a dihedral angle of 81.9 (1)° while the acetyl and carboxyl groups form dihedral angles of 74.0 (1) and 26.4 (2)°, respectively, with the benzene rings to which they are bound. In the crystal, mol-ecules are linked by pairs of O-H⋯O hydrogen bonds between the carboxyl groups...

In the title compound, C(8)H(6)N(2)O(6), the O atoms of the nitro groups, the methyl H atoms and the carboxyl C=O and C-OH groups are disordered over two sets of sites with an occupancy ratio of 0.595 (16):0.405 (16). In the crystal, inversion dimers linked by pairs of O-H⋯O hydrogen bonds arise for both carboxyl disorder components and C-H⋯O bonds and weak C-H⋯π inter-actions consolidate the p...

In the crystal structure of the title compound, C(11)H(11)FO(2), the methine CH forms an intra-molecular hydrogen bond with the carboxyl- O atom. The mol-ecules form dimers through hydrogen bonding between carboxyl- groups. These dimers are linked to each other by C-H⋯O contacts between the benzene and carbonyl groups of adjoining mol-ecules. In addition, there are weak inter-molecular C-H⋯F co...

In the title compound, [Sn(CH(3))(3)(C(7)H(2)Cl(3)O(2))](n), the tin(IV) atom exhibits a slightly distorted trigonal-bipyramidal geometry with two O atoms of symmetry-related carboxyl-ate groups in the axial positions and three methyl groups in the equatorial positions. In the crystal structure, the metal atoms are linked by carboxyl-ate bridges into polymeric chains extending along the b axis.

Bacteria have a great influence on the migration behaviour of heavy metals in the environment. Lipopolysaccharides form the main part of the outer membrane of Gram-negative bacteria. We investigated the interaction of the uranyl cation (UO2(2+)) with lipopolysaccharide (LPS) from Pseudomonas aeruginosa by using potentiometric titration and time-resolved laser-induced fluorescence spectroscopy (...

1. The change in viscosity and the corresponding increase in the carboxyl groups, as determined by the formol titration, has been determined in gelatin solutions during the progress of hydrolysis by pepsin. 2. Very marked changes in viscosity are found to result from very slight chemical changes. If the viscosity is increased by the addition of acid a greater change in viscosity (volume of solu...