Synthesis of DNA interactive C3-trans-cinnamide linked β-carboline conjugates as potential cytotoxic and DNA topoisomerase I inhibitors

A series of new C3-trans-cinnamide linked β-carboline conjugates has been synthesized by coupling between various β-carboline amines and substituted cinnamic acids. Evaluation of their anti-proliferative activity against a panel of selected human cancer cell lines such as A549 (lung cancer), MCF-7 (breast cancer), B16 (melanoma), HeLa (cervical cancer) and a normal cell line NIH3T3 (mouse embryonic fibroblast cell line), suggested that the newly designed conjugates are considerably active against all the tested cancer cell lines with IC₅₀ values 13–45?nM. Moreover, the conjugates 8v and 8x were the most active against MCF-7 cells (14.05?nM and 13.84?nM respectively) and also even potent on other cell lines tested. Further, detailed investigations such as cell cycle analysis, apoptosis induction study, topoisomerase I inhibition assay, DNA binding affinity and docking studies revealed that these new conjugates are DNA interactive topoisomerase I inhibitors.     

Dosimetric evaluation of image based brachytherapy using tandem ovoid and tandem ring applicators

Aim

The aim of the study is to evaluate the differences in dosimetry between tandem-ovoid and tandem-ring gynaecologic brachytherapy applicators in image based brachytherapy.

Multicomponent reaction derived small di- and tri-carbohydrate-based glycomimetics as tools for probing lectin specificity

Glycoconjugate Journal - Lectins, carbohydrate-binding proteins, play important functions in all forms of life from bacteria and viruses to plants, animals, and humans, participating in...     

Database of cell signaling enzymes

This paper describes a database for cell signaling enzymes. Our web database offers methods to study, interpret and compare cell-signaling enzymes. Searching and retrieving data from this database has been made easy and user friendly and it is well integrated with other related databases. We believe the end user will be benefited from this database. AVAILABILITY: http://www.sastra.edu/dcse/index.html.     

Development of a process to manufacture PEGylated orally bioavailable insulin

To make insulin orally bioavailable, insulin was modified by covalent attachment (conjugation) of a short-chain methoxy polyethylene glycol (mPEG) derivative to the ε-amino group of a specific amino acid residue (LysB(29)). During the conjugation process, activated PEG can react with any of the free amino groups, the N-terminal of the B chain (PheB(1)), the N-terminal of the A chain (GlyA(1)), and the ε-amino group of amino acid (LysB(29)), resulting in a heterogeneous mixture of conjugated products. The abundance of the desired product (Methoxy-PEG(3)-propionyl--insulin at LysB(29):IN-105) in the conjugation reaction can be controlled by changing the conjugation reaction conditions. Reaction conditions were optimized for maximal yield by varying the proportions of protein to mPEG molecule at various values of pH and different salt and solvent concentrations. The desired conjugated molecule (IN-105) was purified to homogeneity using RP-HPLC. The purified product, IN-105, was crystallized and lyophilized into powder form. The purified product was characterized using multiple analytical methods including ESI-TOF and peptide mapping to verify its chemical structure. In this work, we report the process development of new modified insulin prepared by covalent conjugation of short chain mPEG to the insulin molecule. The attachment of PEG to insulin resulted in a conjugated insulin derivative that was biologically active, orally bioavailable and that showed a dose-dependent glucose lowering effect in Type 2 diabetes patients.     

Discovery of curcumin inspired sulfonamide derivatives as a new class of carbonic anhydrase isoforms I,II, IX,and XII inhibitors

A series of curcumin inspired sulfonamide derivatives was prepared from various chalcones and 4-sulfamoyl benzaldehyde via Claisen–Schmidt condensation. All new compounds were assayed as inhibitors of four human isoforms of the metalloenzyme carbonic anhydrase (hCA, EC 4.2.1.1) isoforms hCA I, II, IX and XII. Interesting inhibitory activities were observed against all these isoforms. hCA I, an isoform involved in several eye diseases was inhibited moderately with K_Is in the range of 191.8–904.2?nM, hCA II, an antiglaucoma drug target was highly inhibited by the new sulfonamides, with K_Is in the range of 0.75–8.8?nM. hCA IX, a tumor-associated isoform involved in cancer progression and metastatic spread was potently inhibited by the new sulfonamides, with K_Is in the range of 2.3–87.3?nM, whereas hCA XII, and antiglaucoma and anticancer drug target, was inhibited with K_Is in the range of 6.1–71.8?nM. It is noteworthy that one of the new compounds, 5d, was found to be almost 9 times more selective against hCA II (K_I =?0.89?nM) over hCA IX and hCA XII, whereas 5e was 3 and 70 times more selective against hCA II (K_I =?0.75?nM) over hCA IX and hCA XII, respectively.     

Allosteric interactions of DNA and nucleotides with S. cerevisiae RSC

RSC (remodel the structure of chromatin) is an essential chromatin remodeler of Saccharomyces cerevisiae that has been shown to have DNA translocase properties. We studied the DNA binding properties of a "trimeric minimal RSC" (RSCt) of the RSC chromatin remodeling complex and the effect of nucleotides on this interaction using fluorescence anisotropy. RSCt binds to 20 bp fluorescein-labeled double-stranded DNA with a K(d) of ～100 nM. The affinity of RSCt for DNA is reduced in the presence of AMP-PNP and ADP in a concentration-dependent manner with the addition of AMP-PNP having more pronounced effect. These differences in the magnitude at which the binding of ADP and AMP-PNP affects the affinity of DNA binding by RSCt suggest that the physical movement of the enzyme along DNA begins between the binding of ATP and its subsequent hydrolysis. Furthermore, the fact that the highest affinity for DNA binding by RSCt occurs in the absence of bound nucleotide offers a mechanistic explanation for the apparent low processivity of DNA translocation by the enzyme.     

Dual action of ATP hydrolysis couples lid closure to substrate release into the group II chaperonin chamber

Group II chaperonins are ATP-dependent ring-shaped complexes that bind nonnative polypeptides and facilitate protein folding in archaea and eukaryotes. A built-in lid encapsulates substrate proteins within the central chaperonin chamber. Here, we describe the fate of the substrate during the nucleotide cycle of group II chaperonins. The chaperonin substrate-binding sites are exposed, and the lid is open in both the ATP-free and ATP-bound prehydrolysis states. ATP hydrolysis has a dual function in the folding cycle, triggering both lid closure and substrate release into the central chamber. Notably, substrate release can occur in the absence of a lid, and lid closure can occur without substrate release. However, productive folding requires both events, so that the polypeptide is released into the confined space of the closed chamber where it folds. Our results show that ATP hydrolysis coordinates the structural and functional determinants that trigger productive folding.     

BCA2/Rabring7 Targets HIV-1 Gag for Lysosomal Degradation in a Tetherin-Independent Manner

BCA2 (Rabring7, RNF115 or ZNF364) is a RING-finger E3 ubiquitin ligase that was identified as a co-factor in the restriction imposed by tetherin/BST2 on HIV-1. Contrary to the current model, in which BCA2 lacks antiviral activity in the absence of tetherin, we found that BCA2 possesses tetherin-independent antiviral activity. Here we show that the N-terminus of BCA2 physically interacts with the Matrix region of HIV-1 and other retroviral Gag proteins and promotes their ubiquitination, redistribution to endo-lysosomal compartments and, ultimately, lysosomal degradation. The targeted depletion of BCA2 in tetherin-expressing and tetherin-deficient cells results in a significant increase in virus release and replication, indicating that endogenous BCA2 possesses antiviral activity. Therefore, these results indicate that BCA2 functions as an antiviral factor that targets HIV-1 Gag for degradation, impairing virus assembly and release.