Studies on the interaction of papain with human placental cystatin by UV, fluorescence and CD spectroscopy

The interaction of activated papain with low molecular weight cystatin (Mr 12500) purified from human placenta has been studied. Analysis of inhibition of caesinolytic activity of papain by cystatin showed stoichiometry of 1:1. Kinetic studies gave an inhibition constant (K(i)) value of 5.5 x 10(-8) M and association rate constant (K(+1)) value of 3.4 x 10(4) (M(-1) s(-1)). All spectroscopic studies showed conformational changes in both papain and cystatin on formation of complex. The data suggest perturbation of environment of aromatic residues and change of their native structure and conformation thereby shedding light on the behaviour of cystatins, especially interaction of placental cystatin with thiol protease inhibitors.     

QSAR studies on antimalarial 2,4-diamino-6-quinazoline sulfonamides

The present paper discusses QSAR studies on antimalarial 2,4-diamino-6-quinazoline sulfonamide derivatives using electronic parameters, namely energy of highest occupied molecular orbitals (EH), energy of lowest unoccupied molecular orbitals (EL) and charge density (CD). The results have shown that better results are obtained by introducing dummy parameters (indicator parameter), Ip. Excellent results are obtained when all the four parameters (EH, EL, CD and Ip) are used in correlation analysis.     

Monitoring of clinical signs in goats with transmissible spongiform encephalopathies

Background  

As there is limited information about the clinical signs of BSE and scrapie in goats, studies were conducted to describe the clinical progression of scrapie and BSE in goats and to evaluate a short clinical protocol for its use in detecting scrapie-affected goats in two herds with previously confirmed scrapie cases. Clinical assessments were carried out in five goats intracerebrally infected with the BSE agent as well as five reported scrapie suspects and 346 goats subject to cull from the two herds, 24 of which were retained for further monitoring. The brain and selected lymphoid tissue were examined by postmortem tests for disease confirmation.     

Breadth and function of antibody response to acute SARS-CoV-2 infection in humans

Serological and plasmablast responses and plasmablast-derived IgG monoclonal antibodies (MAbs) have been analysed in three COVID-19 patients with different clinical severities. Potent humoral responses were detected within 3 weeks of onset of illness in all patients and the serological titre was elicited soon after or concomitantly with peripheral plasmablast response. An average of 13.7% and 3.5% of plasmablast-derived MAbs were reactive with virus spike glycoprotein or nucleocapsid, respectively. A subset of anti-spike (10 of 32) antibodies cross-reacted with other betacoronaviruses tested and harboured extensive somatic mutations, indicative of an expansion of memory B cells upon SARS-CoV-2 infection. Fourteen of 32 anti-spike MAbs, including five anti-receptor-binding domain (RBD), three anti-non-RBD S1 and six anti-S2, neutralised wild-type SARS-CoV-2 in independent assays. Anti-RBD MAbs were further grouped into four cross-inhibiting clusters, of which six antibodies from three separate clusters blocked the binding of RBD to ACE2 and five were neutralising. All ACE2-blocking anti-RBD antibodies were isolated from two recovered patients with prolonged fever, which is compatible with substantial ACE2-blocking response in their sera. Finally, the identification of non-competing pairs of neutralising antibodies would offer potential templates for the development of prophylactic and therapeutic agents against SARS-CoV-2.     

Conformational transitions induced by in vitro macromolecular crowding lead to the amyloidogenesis of buffalo heart cystatin

The biological cells and extracellular matrix exhibit a highly crowded environment, called as macromolecular crowding. Crowding significantly influences protein structure and may lead to its aggregation. In the present study, buffalo heart cystatin (BHC), after purification from buffalo heart tissue, has been used as a model protein for studying effect of macromolecular crowding in the presence of high concentrations of bovine serum albumin (BSA), poly‐ethylene glycol‐1000 (PEG‐1000), and poly‐ethylene glycol‐4000 (PEG‐4000). Cystatins are thiol protease inhibitors and found to be involved in various important physiological processes. Functional inactivation of BHC was observed upon crowding, which varied as a function of concentration and molecular weight of crowding agents as well as incubation time. Structural changes of BHC at tertiary and secondary level were detected with the help of fluorescence and CD spectroscopy. CD analysis showed changes of α‐helix to β‐sheet, which could be due to aggregation. The ANS‐fluorescence study suggested the unfolding and presence of some partially folded intermediates. Increase in ThT‐fluorescence and absorption of Congo red spectra with red shift, confirmed the amyloid type aggregation of BHC in the presence of various crowding agents. Finally, electron microscopy provided the physical evidence about the formation of amyloid fibrils. Results suggested that among the various crowding agents used, amyloidogenesis of BHC was maximal in case of BSA followed by PEG‐4000 and least for PEG‐1000. The present work makes an important contribution in crowding mediated protein aggregation, which can have implications of potential interest. Copyright © 2015 John Wiley & Sons, Ltd.     

Interaction pattern for the complex of B-DNA Fullerene compounds with a set of known replication proteins using docking study

Fullerenes have attracted considerable attention due to their unique chemical structure and potential applications which has opened wide venues for possible human exposure to various fullerene types. Therefore, in depth knowledge of how fullerene may interfere with various cellular processes becomes quite imperative. The present study was designed to investigate how the presence of fullerene affect the binding of DNA with different enzymes involved in replication process. Different fullerenes were first docked with DNA and then binding scores of different enzymes was analyzed with fullerene docked DNA. C30, C40 & C50 once docked with DNA, reduced the binding score of primase, whereas no significant change in the binding score was observed with the helicase, ssb protein, dna pol δ, dna pol ε, ligase, DNA clamp, and topoisomerases. On the contrast, the binding score of RPA14 decreases in fluctuating manner while interacting with increasing molecular weight of fullerene bound single-stranded DNA complex. The study revealed the affect of fullerene family interacting with DNA on the binding pattern of enzymes involved in replication process. Study suggests that the presence of most of fullerenes may not affect the activity of these enzymes necessary for replication process whereas C30, C40 & C50 may disrupt the activity of primase, (strating point for DNA polymerase) its docking score decreases from 13820 to 10702.     

Alopecia in Harlequin mutant mice is associated with reduced AIF protein levels and expression of retroviral elements

Mammalian Genome - We investigated the contribution of apoptosis-inducing factor (AIF), a key regulator of mitochondrial biogenesis, in supporting hair growth. We report that pelage abnormalities...