Development of selective and reversible pyrazoline based MAO-A inhibitors: Synthesis,biological evaluation and docking studies

3,5-Diaryl pyrazolines analogs were synthesized and evaluated for their monoamine oxidase (MAO) inhibitory activity. The compounds were found reversible and selective towards MAO-A with selectivity index in the magnitude of 10³–10⁵. The docking studies were carried out to gain further structural insights of the binding mode and possible interactions with the active site of MAO-A. Interestingly, the theoretical (K_i) values obtained by molecular docking studies were in congruence with their experimental (K_i) values.     

Physicochemical ProPerties and binding-site amino acid residues of galactoside-binding Protein of human Placenta

The galactose-binding lectin of human Placenta has been Purified to homogeneity by affinity chromatograPhy on asialo-fetuin column. The Protein, extractable from the tissue only with lactose is aPParently membrane-bound. Molecular weight determination of native Protein and subunit indicated a dimer of l3.4 kDa subunits. Inhibition of haemagglutination with various saccharides indicate that thiodigalactoside is the best inhibitor followed by lactose. However,P-nitroPhenyl-and 1-O-methyl derivatives of galactose showed that α-anomers inhibited slightly better than β-anomer. Modification of amino acid residues indicated involvement of arginine, lysine and histidine residues at the saccharidebinding site. Cysteine residue modificatioin also abolished haemagglutinating activity. Amino acid comPosition of the lectin is also Presented.     

Preliminary x-ray investigation of an orthorhombic crystal form of human plasma albumin.

An orthorhombic form of single crystals of human plasma albumin, suitable for x-ray diffraction studies, has been grown with ammonium sulfate from protein solutions purified from fresh frozen single donor plasma as well as from a commercial sample of plasma albumin. The space group is P2(1)2(1)2 with 12 molecules in the unit cell. The cell dimensions are: a = 133.3 +/- 1.2 A, b = 274.8 +/- 3.3 A,, and c = 58.02 +/- 0.02 A.     

Binding of an antagonistic monoclonal antibody to an intact and fragmented EGF-receptor polypeptide

A murine monoclonal antibody (No. 425) raised against human A431 carcinoma cells specifically immunoprecipitates the 170,000 molecular weight epidermal growth factor (EGF)-receptor from extracts of A431 cells as well as from extracts of human placenta and cultured fibroblasts, but does not recognize the murine receptor. Binding to the external domain of the human EGF-receptor was indicated by indirect immunofluorescent staining of fixed nonpermeable cells. The antibody binds to both glyco- and aglycoreceptor forms, indicating that the epitope is a part of the polypeptide chain. Binding of the antibody to the receptor is conformation dependent; i.e., denatured receptors lacking EGF-binding activity are not recognized by the antibody. The results of antibody binding studies indicate that the epitope is closely linked to the EGF binding active site, and is common to both high- and low-affinity EGF-receptors. Interaction of this epitope with the antibody inhibits EGF binding and bioactivity, and triggers receptor down-regulation, but does not generate EGFlike kinase-stimulatory or mitogenic responses either in vitro or in vivo. The antibody was tested for its ability to bind to domain-sized fragments of the 170-kDa EGF-receptor. It can recognize both the proteolytically generated 110-kDa EGF binding peptide, and a soluble 100-kDa EGF-receptor secreted by A431 cells. This indicates that the epitope recognized this antibody retains its conformation after proteolytic separation of the EGF binding domain from the rest of the receptor molecule.     

Circular dichroism and fluorescence investigations on Vicia faba lectin-saccharide binding.

Vicia faba lectin contained 40-57% beta-conformation, 4-23% alpha-conformation along with random coil at pH 7.2 depending upon the analytical methods used. The percentage of beta-conformation increased with the addition of N-acetyl-D-glucosamine or methyl alpha-D-mannopyranoside. The structural transitions of V. faba lectin were affected by alkali at pH 9.6 and 10.6. Binding constants and free energy changes for the interaction between V. faba lectin and N-acetyl-D-glucosamine and methyl alpha-D-mannopyranoside were estimated at pH 7.2 using the c.d. and fluorescence methods.     

Release of low density lipoprotein from its cell surface receptor by sulfated glycosaminoglycans.

The sulfated glycosaminoglycan, heparin, was found to release 125I-labeled low density lipoprotein (125I-LDL) from its receptor site on the surface of normal human fibroblasts. Measurement of the amount of 125I-LDL released by heparin permitted the resolution of the total cellular uptake of 125I-LDL at 37 degrees C into two components: first, an initial rapid, high affinity binding of the lipoprotein to the surface receptor, from which the 125I-LDL could be released by heparin, and second, a slower process attributable to an endocytosis of the receptor-bound lipoprotein, which rendered it resistant to heparin release. At 4 degrees C the amount of heparin-releasable 125I-LDL was similar to that at 37 degrees C, but interiorization of the lipoprotein did not occur at the lower temperature. The physiologic importance of the cell surface LDL receptor was emphasized by the finding that mutant fibroblasts from a subject with homozygous Familial Hypercholesterolemia, which lack the ability to take up 125I-LDL at 37 degrees C, did not show cell surface binding of 125I-LDL, as measured by heparin release, at either 4 degrees C or 37 degrees C. Although heparin released 125I-LDL from its binding site, it did not release 3H-concanavalin A from its surface receptor, and conversely, alpha-methyl-D-mannopyranoside, which released 3H-concanavalin A, did not release surface-bound 125I-LDL. When added to the culture medium simultaneously with LDL, heparin prevented the binding of LDL to its receptor and hence prevented the LDL-mediated suppression of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity. The uptake of LDL by fibroblasts is proposed as a model of receptor-mediated adsorptive endocytosis of macromolecules in human cells.     

Laccase production in solid‐state and submerged fermentation by Pleurotus ostreatus

A solid‐state fermentation (SSF) system for production of an industrially important enzyme laccase by Pleurotus ostreatus was developed by using potato dextrose yeast extract medium and polyurethane foam as a supporting material. The maximum laccase production in the SSF system was as high as 3×10⁵ U/L. Addition of inducers, such as copper and ferulic acid, further enhanced the laccase production in SSF. Moreover, the time required for the maximum laccase production was reduced to 6 days compared to 10 days reported earlier. The improvement achieved by the SSF system was investigated by comparing it to a submerged fermentation system (SmF), both experimentally and by using a standard theoretical model along with a parameter sensitivity analysis. Laccase production in SSF was found to be twice of that in SmF. One of the main reasons for higher laccase production in SSF compared to SmF was possibly due to the presence of higher proteolytic activity in SmF. Strong proteolytic activity in SmF presumably caused subsequent laccase degradation, which lowered the ultimate laccase production in SmF compared to SSF.     

Measurement of selective effect of insulin on glucose disposal from labeled glucose oral test minimal model

The oral glucose minimal model (OMM) measures insulin sensitivity (S(I)) and the glucose rate of appearance (R(a)) of ingested glucose in the presence of physiological changes of insulin and glucose concentrations. However, S(I) of OMM measures the overall effect of insulin on glucose utilization and glucose production. In this study we show that, by adding a tracer to the oral dose, e.g., of a meal, and by using the labeled version of OMM, OMM* to interpret the data, one can measure the selective effect of insulin on glucose disposal, S(I)*. Eighty-eight individuals underwent both a triple-tracer meal with the tracer-to-tracee clamp technique, providing a model-independent reference of the R(a) of ingested glucose (R(a meal)(ref)) and an insulin-modified labeled intravenous glucose tolerance test (IVGTT*). We show that OMM* provides not only a reliable means of tracing the R(a) of ingested glucose (R(a meal)) but also accurately measures S(I)*. We do so by comparing OMM* R(a meal) with the model-independent R(a meal)(ref) provided by the tracer-to-tracee clamp technique, while OMM* S(I)* is compared with both S(I)(* ref), obtained by using as known input R(a meal)(ref), and with S(I)* measured during IVGTT*.     

Viral infection and neural stem/progenitor cell's fate: implications in brain development and neurological disorders

Viral infections in the prenatal (during pregnancy) and perinatal period have been a common cause of brain malformation. Besides the immediate neurological dysfunctions, virus infections may critically affect CNS development culminating in long-term cognitive deficits. Most of these neurotropic viruses are most damaging at a critical stage of the host, when the brain is in a dynamic stage of development. The neuropathology can be attributed to the massive neuronal loss induced by the virus as well as lack of CNS repair owing to a deficit in the neural stem/progenitor cell (NSPC) pool or aberrant formation of new neurons from NSPCs. Being one of the mitotically active populations in the post natal brain, the NSPCs have emerged as the potential targets of neurotropic viruses. The NSPCs are self-renewing and multipotent cells residing in the neurogenic niches of the brain, and, therefore, hampering the developmental fate of these cells may adversely affect the overall neurogenesis pattern. A number of neurotropic viruses utilize NSPCs as their cellular reservoirs and often establish latent and persistent infection in them. Both HIV and Herpes virus infect NSPCs over long periods of time and reactivation of the virus may occur later in life. The virus infected NSPCs either undergoes cell cycle arrest or impaired neuronal or glial differentiation, all of which leads to impaired neurogenesis. The disturbances in neurogenesis and CNS development following neurotropic virus infections have direct implications in the viral pathogenesis and long-term neurobehavioral outcome in infected individuals.