Cellular signalling and free-radical modulating activities of the novel peptidomimetic L-glutamyl-histamine.

A novel histamine-containing peptidomimetic, L-glutamyl-histamine (L-Glu-Hist), has been synthesized and characterized as a possible cytokine mimic which might lead to cellular responses of improved specificity. The energy-minimized 3-D conformations of L-Glu-Hist derived from its chemical structure stabilize Fe2+-chelating complexes. L-Glu-Hist concentration-dependently accelerates a decrease in ferrous iron in ferrous sulfate solution and shows ferroxidase-like activity at concentrations less than 3 mM in the phenanthroline assay, whereas in the concentration range 3-20 mM it restricts the availability of Fe2+ to phenanthroline by chelation of iron ions.

Multi-competitive enzymatic reactions in organic media: a simple test for the determination of lipase fatty acid specificity.

Multiple substrate competition was kinetically analyzed to study lipase-catalyzed reactions in organic media. For each substrate, a competitive factor (the ratio of the specificity constants kcat/Km) was measured by reference to the best substrate using a mixture of fatty acid ethyl esters submitted to a solvolysis reaction by n-propanol. A scale of competitive factors was established which quantitatively described the lipase specificity.

Lipase-catalyzed reactions in organic media: competition and applications.

Lipases (triacylglycerol acylhydrolase, EC 3.1.1.