Two fatty acid-binding proteins expressed in the intestine interact differently with endocannabinoids.

Two different members of the fatty acid-binding protein (FABP) family are found in enterocyte cells of the gastrointestinal system, namely liver-type and intestinal fatty acid-binding proteins (LFABP and IFABP, also called FABP1 and FABP2, respectively). Striking phenotypic differences have been observed in knockout mice for either protein, for example, high fat-fed IFABP-null mice remained lean, whereas LFABP-null mice were obese, correlating with differences in food intake. This finding prompted us to investigate the role each protein plays in directing the specificity of binding to ligands involved in appetite regulation, such as fatty acid ethanolamides and related endocannabinoids.

New therapeutic approaches and novel alternatives for organophosphate toxicity.

Organophosphate compounds (OPCs) are commonly used as pesticides and were developed as nerve agents for chemical warfare. Exposure to OPCs results in toxicity due to their covalent binding and inhibition of acetylcholinesterase (AChE). Treatment for toxicity due to OPC exposure has been largely focused on the reactivation of AChE by oxime-based compounds via direct nucleophilic attack on the phosphorous center.

Discovery of New Classes of Compounds that Reactivate Acetylcholinesterase Inhibited by Organophosphates.

Acetylcholinesterase (AChE) that has been covalently inhibited by organophosphate compounds (OPCs), such as nerve agents and pesticides, has traditionally been reactivated by using nucleophilic oximes. There is, however, a clearly recognized need for new classes of compounds with the ability to reactivate inhibited AChE with improved in vivo efficacy. Here we describe our discovery of new functional groups--Mannich phenols and general bases--that are capable of reactivating OPC--inhibited AChE more efficiently than standard oximes and we describe the cooperative mechanism by which these functionalities are delivered to the active site.

Three-strand exchange by the Escherichia coli RecA protein using ITP as a nucleotide cofactor: mechanistic parallels with the ATP-dependent reaction of the RecA protein from Streptococcus pneumoniae.

The RecA protein from Escherichia coli promotes an ATP-dependent three-strand exchange reaction between a circular single-stranded DNA (ssDNA) and a homologous linear double-stranded (dsDNA). We have now found that under certain conditions, the RecA protein is also able to promote the three-strand exchange reaction using the structurally related nucleoside triphosphate, ITP, as the nucleotide cofactor. However, although both reactions are stimulated by single-stranded DNA-binding (SSB) protein, the ITP-dependent reaction differs from the ATP-dependent reaction in that it is observed only at low SSB protein concentrations, whereas the ATP-dependent reaction proceeds efficiently even at high SSB protein concentrations.

Complete inhibition of Streptococcus pneumoniae RecA protein-catalyzed ATP hydrolysis by single-stranded DNA-binding protein (SSB protein): implications for the mechanism of SSB protein-stimulated DNA strand exchange.

The ATP-dependent three-strand exchange activity of the Streptococcus pneumoniae RecA protein (RecA(Sp)), like that of the Escherichia coli RecA protein (RecA(Ec)), is strongly stimulated by the single-stranded DNA-binding protein (SSB) from either E. coli (SSB(Ec)) or S. pneumoniae (SSB(Sp)).