Molecular Modeling as a Powerful Tool for the Mapping of Fibroblast Growth Factor Receptor-1 Ligand Binding Determinants

Molecular modeling has allowed us to propose that one main contact surface of the Fibroblast Growth Factor Receptor -1 (FGFR-1) to the ligand FGF-1 is formed by a 16 amino acid sequence comprised by the C-terminal region of the domain II (DII) plus the hinge linking DII and DIII domains and the N-terminal region of domain III (DIII). Therefore, this sequence was used to design the following three peptides: Ac-YQLDVVERS-NH₂ (R1); Ac-YQLDVVERSPHRPILQ-NH₂ (R2) and Ac-RSPHRPILQ-NH₂ (R3). The synthetic peptides were tested in their ability to inhibit the mitogenic activity of FGF-1 and FGF-2 in cultured Balb/c 3T3 fibroblasts. The results showed that R1 and R2 inhibited the activity of FGF-1 (ID₅₀ = 40 -50 7M) but not that of FGF-2. Molecular modeling studies of R1 and its docking to FGF-1 suggested that this peptide could assume a conformation very similar to that found in the corresponding segment of FGFR-1. All these results support our hypothesis that the C-terminal residues of the DII domain, represented by peptide R1, are part of a surface responsible for the binding of FGF-1 to FGFR-1 but not of FGF-2. Also, they indicate that peptide R1 may be useful for the development of small selective peptide inhibitors of the FGF-1 biological activities.     

Central autonomic control of the heart, angina, and pathogenic mechanisms of post-myocardial infarction depression.

Depression can develop in 20% of the patients with a myocardial infarction (MI). Pathobiological mechanisms underlying the development of mood disorders in these patients are unknown. Since post-MI depression has been associated with increased risk of mortality we hypothesized that dysfunction of limbic circuitry is part of the pathogenic processes. Both mood and cardiovascular functions are controlled by the limbic system. Here, we will review a set of experiments that support this hypothesis. Using the retrograde transneuronal transport of pseudorabies virus central autonomic cardiomotor circuitry was identified and Fos protein expression was used for characterization of networks participating in cardiac pain perception, evaluation, and initiation of coping responses. A modified conscious rat model of acute heart pain was employed for induction of cerebral Fos protein expression. Experiments investigating the effects of MI on cerebral activity in the rat showed a selective regional endothelial leakage mainly in the prefrontal cortex, and most severely in the anterior cingulate cortex. This effect was mimicked with intravenous injections of recombinant Tumor Necrosis Factor alpha, which led to the hypothesis that post-MI depression evolves from selective dysfunction of the prefrontal, anterior cingulate cortex in response to (excessive) release of mediators of inflammation. Evidence is provided that cingulate cortex dysfunction may underlie occurrence of mood disorders and derangement of cardiac autonomic control, which would explain the increased risk of mortality associated with post-MI depression.     

Nucleoside Analogues of Purine with a 1,2-Disubstituted Cyclopentene Ring

Abstract

One, two-disubstituted carbonucleoside analogues of purine with unsaturated carbocyclic were synthesized by construction of the heterocyclic base about the primary amino group of the amino alcohol 4 intermediate, which was also synthesized in good yield starting from cyclopentadiene.     

Theoretical investigation of the mechanism for the reductive dehalogenation of methyl halides mediated by the Co<Superscript>I</Superscript>-based compounds cobalamin and cobaloxime

Theoretical calculations focusing on the cleavage of the C–X bond in methyl halides (CH₃X; X?=?Cl, Br, I) as mediated by Co^I-based systems have been carried out using the hybrid functional ωB97-XD together with the basis set 6–311++G(2d,2p). A total of seven Co^I-based compounds were evaluated: cob[I]alamin (Co^ICbl) in its base-on form and cobaloxime (Co^ICbx) with either no ligand or different ligands (either pyridine (PYR), tributylphosphine (TBP), dimethyl sulfide (DMS), cyclohexylisocyanide (CI), or 5,6-dimethylbenzimidazole (DMB)) at the lower axial position. For the large Co^ICbl system, an ONIOM scheme was employed, where the high layer was described at the DFT level and the low layer was computed using the semi-empirical method PM6. A full DFT model was employed for the Co^ICbx cases. An S_N2-like mechanism was evaluated in all cases. The intrinsic reaction coordinate profiles suggested early transition states with activation energies of ≈ 12 kcal/mol, ≈ 10 kcal/mol, and ≈ 5 kcal/mol for C–Cl, C–Br, and C–I cleavage, respectively, which is consistent with the leaving group abilities of these halides. The evolutions of the atomic charges in and the bond orders of Co–C and C–X were computed, and the results confirmed the existence of early transition states (δB_av≈ 40%), where the polarization C^δ+–X^δ? (%E_v?≈?43%) is the determining factor in the reaction process. Finally, a comparison of all the determined parameters showed that the reaction in the DMB–Co^ICbx system resembles the process that occurs in the larger Co^ICbl, suggesting that the former system could be a reliable model for the study of reductive dehalogenation mediated by vitamin B₁₂, which is key to the anaerobic microbiological treatment of halocarbon contaminants.     

Effectiveness of indoleacetic acid,indolebutyric acid and naphthaleneacetic acid during adventitious root formation in vitro in Malus ‘Jork 9’

The production of an antifungal spirostanol saponin designated SC-1 has been detected in cell suspension cultures of the Mexican species Solanum chrysotrichum. Batch cultures of a cell suspension obtained from hypocotyl derived calluses of this species were grown for 25 days in shake flasks containing Murashige & Skoog (MS) medium. Throughout the growth cycle, fresh and dry weight, SC-1 yield, and uptake of sucrose, glucose and fructose were determined. The effects of inoculum size and sucrose concentration on the biomass accumulation and synthesis of the active metabolite, were studied. The maximum SC-1 production, above 14 mg.g⁻¹ (which was fifty times that of field grown plants), was reached after 20 days using a 2% inoculum and complete MS medium supplemented with 2 mgl⁻¹ 2,4-D, 2 mg l⁻¹kinetin, and sucrose between 30 and 45 gl⁻¹. . This revised version was published online in June 2006 with corrections to the Cover Date.     

Three-dimensional Model Structure for the Extracellular Domains of Fibroblast Growth Factor Receptor - 1 (FGFR-1)

We have developed a model for the two immunoglobulin-like extracellular domains DII and DIII of the FGF receptor 1 (FGFR-1), giving a special attention to the determination of the appropriate Ig set. The DII domain was aligned with the C-terminal domain of myosin light chain kinase (telokin) of the I set, and the DIII domain with the variable domain of the Bence-Jones immunoglobulin of the V set. Two assemblies, corresponding to different propositions for the domains relative orientation, have been refined and compared.Electronic Supplementary Material available.