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The identification of x-ray crystal structure of cathepsin B (CTSB) in the early 90's enabled researchers to embark on a journey to understand and demystify its multiple catalytic mechanisms (endopeptidase/carboxypeptidase/peptidyl-dipeptidase) in diverse physiological processes and their switching into one another under different conditions. The engagement of CTSB in different pathological conditions due to its over-expression further highlighted the enhanced research interest around the domain. The occurrence of over-expressed CTSB in various diseases like Alzheimer's, cancer, arthritis, cardiovascular, etc., and the use of CTSB inhibitors for the treatment of these diseases have established its involvement in different pathological conditions. Such an understanding tempted researchers to design, synthesize, and screen diverse classes of compounds against CTSB. This in turn, helped in understanding their interactions with the active sites of the enzyme. Heterocyclic compounds comprise a very rich and broad class of medicinally important compounds that also hold great potential for CTSB inhibition. This review covers the CTSB inhibition potential of various natural and synthetic heterocyclic scaffolds. Researchers working in the fields of molecular modeling, drug design and development, and enzyme inhibitors can benefit significantly from this review.

Enzymes are the precious gift of nature to humans. The wise utilization of enzymes may reduce energy needs of humans and the Immobilization technique can help a lot in this regard. This aspect overcomes limitations of the enzymes, therefore providing an opportunity to explore enzymatic chemistry further. In the present context, it is quite cumbersomecostly to identify the amino acid of enzymes involved in the covalent mode of Immobilization. In the present study, molecular modeling techniques were used to do this difficult task. The present work used molecular modeling methods to extract information about the immobilization of α-Amylase (E.C.3.2.1.1) on Dialdehyde Cellulose. The Lysine residue is the most probable residue to interact with Dialdehyde Cellulose. In the present work, a total of 23 lysine residues were used to study covalent binding behavior with α-Amylase. It was found that if Lys

Background Advanced glycation end products (AGEs) have shown to possess antigenicity. This study analyzes the detrimental effect of non-enzymatic glycation on human serum albumin (HSA) leading to the production of antibodies. Methods HSA (20 μM) incubated with d -glucose formed AGEs confirmed by scanning electron microscopy (SEM). DNA-damage was assessed with comet assay. Antibodies against in-vitro formed AGEs was evaluated in the sera of diabetic patients by enzyme-linked immunosorbent assay. Molecular docking was performed to demonstrate affinity of native and glycated-HSA with IgG. Low-grade systemic inflammation was quantified with IL-4, IL-6, TNF-α and NF-кβ in serum and mRNA expression. Results Scanning Electron Microscopy showed the formation of aggregates in glycated-HSA. Comet assay showed DNA damage T2DM with CKD. Serum auto-antibodies in diabetes patients with chronic kidney disease (CKD) showed appreciably high recognition with glycated-HSA compared to native HSA. Molecular docking showed less affinity of glycated-HSA with IgG. Serum IL-4, IL-6, and TNF-α were found significantly higher in T2DM with CKD compared to T2DM and healthy ones. mRNA expression of IL-4, IL-6 and NF-кβ are also found significantly higher in T2DM with CKD. Conclusion The non-enzymatic glycation-induced damage to the HSA generate neo-epitopes that possess immunogenic response and low-grade systemic inflammation.

In this study we have characterized the biochemical and biophysical interactions of curcumin with the mitotic kinesin Eg5 which plays a pivotal role in the separation of centrosomes during cell division. Curcumin bound to the purified Eg5 (Eg5-437H) with a Kd value of 7.8μM. The temperature dependent binding analysis and evaluation of thermodynamic parameters indicated the involvement of static quenching mechanism in the binding process. Evidences from competition experiment with monastrol indicated that curcumin bound to Eg5 at a novel druggable site. Using Forster resonance energy transfer the distance between curcumin and monastrol binding site from TRP127 on Eg5-437H was found to be 33A and 17A respectively. Curcumin inhibited the ATPase activity of Eg5 motor and perturbed the dynamic interactions between Eg5 and microtubules. Results from circular dichroism studies and molecular dynamics simulations suggest that curcumin binding might perturb the Eg5-437H secondary structure which could be the reason behind its inhibitory effects on Eg5. Cell culture studies performed in HeLa cells indicated that curcumin potentiated the mitotic arrest and monopolar spindle formation in synergism with monastrol, indicating that both ligands could bind simultaneously to the same target.

The emergence of albumin as a biocatalyst has created continuous interest of researchers for its application not only in the field of asymmetric oxidations and reductions but also in chemical reactions such as additions, condensations and eliminations. In the present work we report the cyclization reactions in presence of an albumin protein, Bovine Serum Albumin (BSA). The work is focused on cyclization of 2'-hydroxychalcone and 2'-aminochalcone to flavanones and azaflavanone, respectively. The results are supported by (1)H NMR studies.

Highlights • Three bio macromolecules cathepsins B, H and L of physiological and pathological significance have been selected for the study. • The molecules have been designed by combining two important pharmacophores their cyclized analogues and were studied for their inhibitory effects on selected enzymes. • Two isomeric forms of chalconesemicarbazones are reported for the first time. • The synthesized compounds showed a competitive inhibition towards cathepsins B, H and L. • Docking experiments were run along with to relate with in vitro studies., Cathepsin B [EC 3.4.22.1], cathepsin H [EC 3.4.22.16] and cathepsin L [EC 3.4.22.15] are the most versatile lysosomal cysteine proteases and are responsible for intracellular protein degradation. These are involved in a number of pathological conditions including tissue degenerative processes. In the present work, we report the synthesis and systematic evaluation of differently substituted chalcones, chalconesemicarbazones, and diarylpyrazolines on cathepsins B, H and L activity. It was found that after a preliminary screening as cysteine protease inhibitors, chalconesemicarbazones were better inhibitors to these cysteine proteases than diarylpyrazolines followed by chalcones. All the synthesized compounds were identified as the best inhibitors to cathepsin L followed by cathepsin B and then cathepsin H. The results are compared with docking studies and it was found that all the compounds resulted in decrease in energy while interacting with the active site of the enzyme.

Bcl-2 (B cell lymphoma-2) is an anti-apoptotic member of Bcl-2 family and its overexpression causes development of several types of cancer. The BH3 domain of pro-apoptotic and BH3-only proteins is capable of binding to Bcl-2 protein to induce apoptosis. This binding is the basis for the development of novel anticancer drug which would likely antagonize Bcl-2 overexpression. In this study we have identified BH3 domain of Bax (Bax BH3) as potentially the best Bcl-2 antagonist by performing docking of BH3 peptides (peptides representing BH3 domain of pro-apoptotic and BH3-only proteins) into the Bcl-2 hydrophobic groove formed by BH3, BH1 and BH2 domains (also referred as BH3 cleft). To predict the best small antagonist for Bcl-2, three groups of small peptides (pentapeptide, tetrapeptide and tripeptide) were designed and screened against Bcl-2 which revealed the structural importance of a set of residues playing a vital role in interaction with Bcl-2. The docking and scoring function identified KRIG and KRI as specific peptides among the screened small peptides responsible for Bcl-2 neutralization and would induce apoptosis. The applied pharmacokinetic and pharmacological filters to all small peptides signify that only IGD has drug-like properties and displayed good oral bioavailability. However, the obtained binding affinity of IGD to Bcl-2 was diminutive. Hence deprotonation, amidation, acetylation, benzoylation, benzylation, and addition of phenyl, deoxyglucose and glucose fragments were performed to increase the binding affinity and to prevent its rapid degradation. Benzoylated IGD tripeptide (IGD(bzo)) was observed to have increased binding affinity than IGD with acceptable pharmacokinetic filters. In addition, stability of Bcl-2/IGD(bzo) complex was validated by Molecular Dynamics (MD) simulations revealing improved binding energy, salt bridges and strong interaction energies. This study suggests a new molecule that inhibits Bcl-2 associated cancer/tumor regression.