Virtual screening and pharmacophore design for a novel theoretical inhibitor of macrophage stimulating factor as a metastatic agent

INTRODUCTION

Metastasis is a crucial aspect of cancer. Macrophage stimulating protein (MSP) is a single chain protein and can be cleaved by serum proteases. MSP has several roles in metastasis. In this in silico study, MSP as a metastatic agent was considered as a drug target.

METHODS

Crystallographic structure of MSP was retrieved from protein data bank. To find a chemical inhibitor of MSP, a library of KEGG compounds was screened and 1000 shape complemented ligands were retrieved with FindSite algorithm. Molegro Virtual Docker (MVD) software was used for docking simulation of shape complemented ligands against MSP. Moldock score was used as scoring function for virtual screening and potential inhibitors with more negative binding energy were obtained. PLANS scoring function was used for revaluation of virtual screening data.

RESULTS

The top found chemical had binding affinity of -183.55 based on MolDock score and equal to -66.733 PLANTs score to MSP structure.

CONCLUSION

Based on pharmacophore model of potential inhibitor, this study suggests that the chemical which was found in this research and its derivate can be used for subsequent laboratory studies.

Virtual screening of 2,3-disubstituted-4(3H)-quinazolinones possessing benzenesulfonamide moiety for COX-2 inhibitor

COX inhibitors which selectively inhibits the inducible COX-2 is an oenzyme that causes inflammation. They are clinically effective anti-inflammatory agents with less gastrointestinal and renal toxicity. However, they lack anti-thrombotic activity and hence lead to increased incidences of adverse cardiovascular trombotic events such as myocardial infarction. Therefore, there is still a need to develop better therapeutic effect and tolerability COX-2 inhibitor. The majority of COX-2 inhibitors are diaryl heterocycles. For optimum COX-2 selectivity and inhibitory potency a -SO(3)CH(3) or a- SO(2)NH(2) substituent at the para-position of phenyl ring was essential. A wide variety of heterocycles can serve as central ring system of the diaryl heterocycles structures. We report the screening of various 2,3-disubstituted-4(3H)-quinazolinones possessing benzenesulfonamide moiety, directly or indirectly bound to the ring system, using the Protein-Ligand ANT System (PLANTS) docking software against the COX-2 enzyme. Various molecular structures of ligands were docked and scored to identify structurally similar ligands to SC-558 (reference ligand) in binding interaction to COX-2 binding site. The results show that 2,3-disubstituted-4(3H)-quinazolinones possess pbenzenesulfonamide moiety at C-2, and phenyl moiety at N-3 binds directly or indirectly to the ring system with high binding affinity. The docked ligand has orientations similar to that observed with SC-558 satisfying Lipinski's rule of five.

Respiration of barley plants; protein catabolism and the formation of amides in starving leaves

In a continuation of earlier studies the nitrogenous constituents of barley leaves have been investigated with the object of gaining more direct evidence on the nature of protein catabolism in starving leaves. Particular attention was given to the origin and identification of the amides. Tissue proteins were separated and partially analyzed by direct and indirect methods. The amino-acids of the barley-leaf protein were very similar to those of the proteins prepared from grasses. From these and other data estimates of the amide-N, glutamic acid and aspartic acid were obtained. The amide-N content of the whole protein of the leaves agreed closely with that of the separated protein. There was evidence that the release of amide-N proceeded uniformly as the proteins were broken down during starvation. Asparagine was identified as a product of catabolism by direct isolation from starved leaves; recovery of the crystalline product amounted to 60% of the total stable amide-N of the crude extract. Glutamine was not isolated, but additional evidence of its presence in the leaves was obtained. An analysis of the relation between proteolysis and formation of amides confirmed several of the suggestions made in a previous discussion. Most of the amide-N of the starved leaves was of secondary origin, and there were clear indications of a secondary synthesis of the aspartic acid combined in asparagine. Glutamine amide-N was formed secondarily during the early stages of starvation, but evidence of the origin of glutamic acid was inconclusive. The data of different experiments indicated that the breakdown of tissue proteins contributed between 20 and 40% of the total carbon lost from the leaves as respiratory carbon dioxide.

Light production by green plants

1. Green plants have been found to emit light of approximately the same color as their fluorescent light for several minutes following illumination. This light is about 10(-3) the intensity of the fluorescent light, about one-tenth second after illumination below saturation or 10(-6) of the intensity of the absorbed light. 2. The decay curve follows bimolecular kinetics at 6.5 degrees C. and reaction order 1.6 at 28 degrees C. 3. This light saturates as does photosynthesis at higher light intensities and in about the same intensity range as does photosynthesis. 4. An action spectrum for light emitted as a function of the wave length of exciting light has been determined. It parallels closely the photosynthetic action spectrum. 5. The intensity of light emission was studied as a function of temperature and found to be optimal at about 37 degrees C. with an activation energy of approximately 19,500 calories. Two-temperature studies indicated that the energy may be trapped in the cold, but that temperatures characteristic for enzymatic reactions are necessary for light production. 6. Illumination after varying dark periods showed initial peaks of varying height depending on the preceding dark period. 7. 5 per cent CO(2) reversibly depresses the amount of light emitted by about 30 per cent. About 3 minutes are required for this effect to reach completion at room temperatures. 8. Various inhibitors of photosynthesis were tested for their effect on luminescence and were all inhibitory at appropriate concentrations. 9. Irradiation with ultraviolet light (2537A) inhibits light production at about the same rate as it inhibits photosynthesis. 10. This evidence suggests that early and perhaps later chemical reactions in photosynthesis may be partially reversible.