Interactions of 5-lipoxygenase with membranes: studies on the association of soluble enzyme with membranes and alterations in enzyme activity.

Treatment of rat basophilic leukemia cells (RBL-1) with the calcium ionophore A23187 resulted in activation of 5-lipoxygenase, as indicated by an induction of leukotriene release [Orning, L., Hammarström, S., & Samuelsson, B.

Purification, characterization, and structural properties of a single protein from rat basophilic leukemia (RBL-1) cells possessing 5-lipoxygenase and leukotriene A4 synthetase activities.

Arachidonate 5-lipoxygenase of rat basophilic leukemia (RBL-1) cells was purified more than 1000-fold by gel filtration and anion exchange protein-high performance liquid chromatography (HPLC). Physical properties of the purified 5-lipoxygenase such as molecular weight (74,000-76,000), N-terminal sequence (30 amino acids), and amino acid composition were determined. The purified enzyme converted [14C]arachidonic acid at 20 degrees to [14C] 5-hydroperoxyeicosatetraenoic acid (5-HPETE) and to [14C]dihydroxyeicosatetraenoic acids (diHETEs).

Further comparison of contractions of the smooth muscle of the guinea-pig isolated vas deferens induced by ATP and related analogs.

Some structural requirements which are important for the contractile activity of adenine nucleotides at P2-purinergic receptors in the guinea-pig isolated vas deferens were examined. The consequences of deletions, substitutions and isosteric rearrangements in 1-N, C-2, C-8, N-9 and N6 of adenine, in the ribose hydroxyls, and in the polyphosphate chain were examined. Several kinds of effects on activity were observed, including potentiation of responses, losses in activity, modifications of response duration, and transitions from biphasic concentration-response curves, which are characteristic of ATP, to monophasic curves.

Binding of 4(5)-[2-(4-azido-2-nitroanilino)ethyl]imidazole to histamine receptors in guinea pig cerebral cortical membranes.

The interaction of 4(5)-[2-(4-azido-2-nitroanilino)ethyl]imidazole (AAH), a photolabile histamine receptor antagonist, with the binding of histamine, mepyramine, and tiotidine to guinea pig cerebral cortical membranes was examined to evaluate the specificity of AAH for histamine H1 and H2 receptors. Saturable, specific binding of [3H]histamine, [3H]mepyramine, and [3H]tiotidine to the membranes was observed. Competition assays were used to assess the relative affinity of AAH for H1- and H2-receptors.

Characterization of [3H]leukotriene D4 binding sites in guinea-pig ventricular myocardium.

[3H]Leukotriene (LT) D4 was used to identify specific LTD4 binding sites in guinea-pig ventricular myocardial membranes. High-performance liquid chromatography analyses indicated that, in the presence of the gamma-glutamyl transpeptidase inhibitor L-serine-borate (80 mM), less than 3% of membrane-bound [3H]LTD4 was converted to [3H]LTC4 or [3H]LTE4 at 30 degrees C. The specific [3H] LTD4 binding, assayed in the presence of 80 mM L-serine-borate, reached a stable steady state within 45 min at 30 degrees C (pH 7.