Antagonism of paraoxon intoxication by recombinant phosphotriesterase encapsulated within sterically stabilized liposomes.

This investigation effort is focused on increasing organophosphate (OP) degradation by phosphotriesterase to antagonize OP intoxication. For these studies, sterically stabilized liposomes encapsulating recombinant phosphotriesterase were employed. This enzyme was obtained from Flavobacterium sp.

Critical role of conserved histidine pairs HNXXH and HDXXH in recombinant human phosphodiesterase 4A.

Cyclic AMP-Phosphodiesterases (cAMP-PDEs) catalyse the hydrolysis cAMP to AMP and thus serve to modulate the ligand-->adenylate cyclase-->cAMP-->PKA signal transduction pathway. PDEs exist as a multigene family of enzymes that bear significant sequence homology in the catalytic domains. The sequence alignment of these domains has revealed the presence of two histidine motifs: motif I, HNXXH, and motif II, HDXXH.

Cyclic AMP-specific phosphodiesterase inhibitor rolipram and RO-20-1724 promoted apoptosis in HL60 promyelocytic leukemic cells via cyclic AMP-independent mechanism.

Phosphodiesterases (PDEs) are responsible for the hydrolysis of cAMP and cGMP which act as intracellular second messengers in a variety of cellular functions. In this paper we report that PDE3 and PDE4 were two dominant classes of PDEs expressed in HL60 cells. The influence of specific PDE inhibitors on apoptosis in HL60 cells was studied.

Inactivation of recombinant monocyte cAMP-specific phosphodiesterase by cAMP analog, 8-[(4-bromo-2,3-dioxobutyl)thio]adenosine 3',5'-cyclic monophosphate.

Two cAMP analogs, 8- and 2- [(4-bromo-2,3-dioxobutyl)thio]adenosine 3',5'-cyclic monophosphate (8- and 2-BDB-TcAMP) have been used in probing the catalytic site of recombinant monocyte cAMP-specific phosphodiesterase (PDE4a). 2-BDB-TcAMP is a reversible and competitive inhibitor (Ki = 5.5 mumol/L) of cAMP hydrolysis by PDE4a, 8-BDB-TcAMP irreversibly inactivates the enzyme in a time- and concentration-dependent manner with a second order rate constant of 0.

Evidence for the presence of essential histidine and cysteine residues in platelet cGMP-inhibited phosphodiesterase.

Camp is a major regulator of platelet function. cGMP-inhibited phosphodiesterase (cGI-PDE) is the predominant platelet enzyme hydrolysing cAMP. The pH-rate profile plot for this enzyme yields pKa values of 6.