Novel tricyclic-alpha-alkyloxyphenylpropionic acids: dual PPARalpha/gamma agonists with hypolipidemic and antidiabetic activity

Synthesis and structure-activity relationships of tricyclic alpha-ethoxy-phenylpropionic acid derivatives guided by in vitro PPARalpha and PPARgamma transactivation data and computer modeling led to the identification of the novel carbazole analogue, 3q, with dual PPARalpha (EC(50) = 0.36 microM) and PPARgamma (EC(50) = 0.17 microM) activity in vitro. Ten days treatment of db/db mice with 3q improved the insulin sensitivity, as measured by OGTT, better than that seen with both pioglitazone and rosiglitazone treatment, suggesting in vivo PPARgamma activity. Likewise, 3q lowered plasma triglycerides and cholesterol in high cholesterol fed rats after 4 days treatment, indicating in vivo PPARalpha activity. Investigations of the pharmacokinetics of selected compounds suggested that extended drug exposure improved the in vivo activity of in vitro active compounds.

Crystal structure of the family 7 endoglucanase I (Cel7B) from Humicola insolens at 2.2 A resolution and identification of the catalytic nucleophile by trapping of the covalent glycosyl-enzyme intermediate

Cellulose is the major polysaccharide component of the plant cell wall and the most abundant naturally produced macromolecule on Earth. The enzymic degradation of cellulose, by cellulases, is therefore of great environmental and commercial significance. Cellulases are found in 12 of the glycoside hydrolase families classified according to their amino acid sequence similarities. Endoglucanase I (Cel7B), from the soft-rot fungus Humicola insolens, is a family 7 enzyme. The structure of the native form of Cel7B from H. insolens at 2.2 A resolution has been solved by molecular replacement using the known Trichoderma reesei cellobiohydrolase I [Divne, Ståhlberg, Reinikainen, Ruohonen, Pettersson, Knowles, Teeri and Jones (1994) Science 265, 524-528] structure as the search model. Cel7B catalyses hydrolysis of the beta-1,4 glycosidic linkages in cellulose with net retention of anomeric configuration. The catalytic nucleophile at the active site of Cel7B has been identified as Glu-197 by trapping of a 2-deoxy-2-fluorocellotriosyl enzyme intermediate and identification of the labelled peptide in peptic digests by tandem MS. Site-directed mutagenesis of both Glu-197 and the prospective catalytic acid, Glu-202, results in inactive enzyme, confirming the critical role of these groups for catalysis.

Characterization of human and rat intestinal trefoil factor produced in yeast

Intestinal trefoil factor (ITF) from human (hITF) and rat (rITF) have been produced in Saccharomyces cerevisiae. The DNA encoding the two peptides were cloned by polymerase chain reactions (PCR) from a human normal colon library and a rat small intestinal epithelial cell library. Recombinant plasmids were constructed to encode a fusion protein consisting of a hybrid leader sequence and the rat and human ITF sequences, respectively. The leader sequence used serves to direct the fusion protein into the secretory (and processing) pathway of the cell. The secreted recombinant hITF was found in a monomer and a dimer form, whereas the rITF was only secreted as a dimer. The secreted peptides were purified by a combination of ionic exchange chromatography and preparative HPLC. From 8 L of yeast fermentation broth, 256 mg of hITF (monomer) and 133 mg of hITF (dimer) were isolated, and from 8.7 L of fermentation broth, 236 mg of rITF (dimer) was isolated. The structure of hITF (monomer), hITF (dimer), and rITF (dimer) was determined by amino acid analyses, peptide mapping, sequence analyses, and electrospray mass spectrometry analyses. In hITF (monomer) six of the seven cysteines are disulfide-linked to form 3 disulfide bridges. Mass analysis indicated that the last cysteine residue (Cys-57) did not exist as free (-SH) cysteine, but have reacted with cysteine to form an S-S linked cystine. Sequence and mass spectrometry analyses as well as peptide mapping showed that the dimer form of both hITF and rITF is mediated by a disulfide bridge between Cys-57 residues of two monomers.

Crystallization and preliminary X-ray analysis of a fungal endoglucanase I

An endoglucanase I (EG1) from a fungal source (Humicola insolens) has been crystallized in a number of forms suitable for X-ray diffraction analysis. Four crystal forms have been grown from various precipitants using vapour phase diffusion methods in hanging drops. Three of these crystal forms diffract to beyond 2.5 A resolution. Two forms, obtained from ammonium sulphate at pH 5.4, or 8.0, grow as tetragonal bipyramids in space group P4(1)22 or P4(3)22, with approximate cell dimensions a = b = 102 A, c = 282 A. The other crystal forms were grown from polyethylene glycol 8000 at pH 8.0. One grows as monoclinic plates, space group P2(1), with cell dimensions a = 66.9 A, b = 75.2 A, c = 86.9 A and beta = 102.9 degrees and the other as long hexagonal rods in space group P6(1)22 or P6(5)22, with cell dimensions a = b = 119 A, c = 83 A.