Potential anticancer peptides design from the cysteine rich plant defensins: An in silico approach

Cancer is the second leading cause of mortality worldwide preceded by cardiovascular diseases. The therapeutic approaches for drug developmentinclude the use of small molecules, antibodies, peptidesor short nucleic acid sequences. The peptide-based drugs have been developed to treat many diseases like cardiovascular diseases, cancer, metabolic disorders, immunological diseases and viral infections. More than 80 peptide drugs are already in the market. These therapeutic peptides have several important benefits over antibodies and proteins due to their small size, ease for chemical synthesis and further the ability to penetrate cell membrane. Furthermore, peptide drugs have high specificity, activity, and affinity. The plant defensins BcDef1, TPP3, NaD1, 2N2R and 2LR3 have been studied for their role in wide range of diseases. This study focussed on the conformation of plant defensins rich in disulfide bonds. The structure for BcDef1 has been predicted from the conformational ensemble. Then, we designed anticancer peptides from these defensins with computational methods. The designed anticancer peptides have been studied for their immunogenicity as well as homology with human proteome. The role of designed peptides has been suggested for interferon-gamma induction, the later has been shown to possess a very important role in cancer

A novel 13 residue acyclic peptide from the marine snail, Conus monile, targets potassium channels

A novel 13-residue peptide Mo1659 has been isolated from the venom of a vermivorous cone snail, Conus monile. HPLC fractions of the venom extract yielded an intense UV absorbing fraction with a mass of 1659 Da. De novo sequencing using both matrix assisted laser desorption and ionization and electrospray MS/MS methods together with analysis of proteolytic fragments successfully yielded the amino acid sequence, FHGGSWYRFPWGY-NH2. This was further confirmed by comparison with the chemically synthesized peptide and by conventional Edman sequencing. Mo1659 has an unusual sequence with a preponderance of aromatic residues and the absence of apolar, aliphatic residues like Ala, Val, Leu, and Ile. Mo1659 has no disulfide bridges distinguishing it from the conotoxins and bears no sequence similarity with any of the acyclic peptides isolated thus far from the venom of cone snails. Electrophysiological studies on the effect of Mo1659 on measured currents in dorsal root ganglion neurons suggest that the peptide targets non-inactivating voltage-dependent potassium channels

Novel peptides of therapeutic promise from Indian conidae

Highly structured small peptides are the major toxic constituents of the venom of cone snails, a family of widely distributed predatory marine molluscs. These animals use the venom for rapid prey immobilization. The peptide components in the venom target a wide variety of membrane-bound ion channels and receptors. Many have been found to be highly selective for a diverse range of mammalian ion channels and receptors associated with pain-signaling pathways. Their small size, structural stability, and target specificity make them attractive pharmacologic agents. A select number of laboratories mainly from the United States, Europe, Australia, Israel, and China have been engaged in intense drug discovery programs based on peptides from a few snail species. Coastal India has an estimated 20-30% of the known cone species; however, few serious studies have been reported so far. We have begun a comprehensive program for the identification and characterization of peptides from cone snails found in Indian Coastal waters. This presentation reviews our progress over the last 2 years. As expected from the evolutionary history of these venom components, our search has yielded novel peptides of therapeutic promise from the new species that we have studied

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

Escherichia coli ilvN Interacts with the FAD Binding Domain of ilvB and Activates the AHAS I Enzyme

The unique multidomain organization in the multimeric Escherichia coli AHAS I (ilvBN) enzyme has been exploited to generate polypeptide fragments which, when cloned and expressed, reassemble in the presence of cofactors to yield a catalytically competent enzyme. Multidimensional multinuclear NMR methods have been employed for obtaining near complete sequence specific NMR assignments for backbone HN, 15N, 13Cα and 13Cβ atoms of the FAD binding domain of ilvB on samples that were isotopically enriched in 2H, 13C and 15N. Unambiguous assignments were obtained for 169 of 177 backbone Cα atoms and 127 of 164 side chain Cβ atoms. The secondary structure determined on the basis of observed 13Cα secondary chemical shifts and sequential NOEs agrees well with the structure of this domain in the catalytic subunit of yeast AHAS. Binding of ilvN to the ilvBα and ilvBβ domains was studied by both circular dichroism and isotope edited solution nuclear magnetic resonance methods. Changes in CD spectra indicate that ilvN interacts with ilvBα and ilvBβ domains of the catalytic subunit and not with the ilvBγ domain. NMR chemical shift mapping methods show that ilvN binds close to the FAD binding site in ilvBβ and proximal to the intrasubunit ilvBα/ilvBβ domain interface. The implication of this interaction on the role of the regulatory subunit on the activity of the holoenzyme is discussed

Solution structures and thermodynamics of cis-trans X-Pro conformers of a novel single disulfide conopeptide

710-728The conopeptide Mo1853 (MW = 1853 Da) consists of 17 residues and a single disulfide bond. Structural studies using homonuclear solution NMR methods (2D 1H,1H DQF-COSY, TOCSY, NOESY and ROESY spectra) revealed that Mo1853 exists as two equally populated cis and trans X–Pro peptide bond conformers which are in slow exchange regime, compared to the chemical shift time scale. Temperature dependence of chemical shifts was measured and using coalescence temperature of two amide protons, the rate of exchange and the free energy of activation for the conformational exchange were determined to be 59 Hz and ≈ 67.2 kJ mol−1, respectively, at 318 K. Additional evidence for this conformational equilibrium was also observed as exchange correlation peaks in the 2D-NOESY and ROESY spectra. Tertiary structures of both the cis (PDB ID 8K3N) and trans (PDB ID 8K3M) conformers were determined using distance restraints, backbone dihedral angle restraints, the disulfide bond restraint and the cis or trans conformation of the X–Pro peptide bond. The trans conformer of Mo1853 is stabilized by hydrogen bonds while the cis conformer seems to be stabilized predominantly by hydrophobic interactions. This was further corroborated by the fact that at lower temperatures, the hydrophobic interactions became weaker reducing the population of the cis conformer with respect to that of the trans conformer. The cis and trans X–Pro peptide bond conformational exchange could be another means to enhance the structural variability of the conopeptides and could have significance in the synergistic functional response caused by the cone snail venom peptides

NMR assignment of 2H^2H, 13C^{13}C and 15N^{15}N labeled amino-terminal domain of apo-pantothenate synthetase from E. coli

Pantothenate (vitamin $b_5$) is an essential precursor for the biosynthesis of coenzyme A (CoA), an essential metabolite for many important cellular processes (Brown et al., 1987). Pantothenate Synthetase (PS) catalyzes the ATP dependent condensation of D-pantoate with $_\beta$-alanine to give rise to pantothenate. Our interest lies in studying the solution-state inter-domain interactions in E. coli PS that results in formation of the catalytic site. As a first step we have cloned and over-expressed an isotopically enriched sample of the dimeric amino-terminal domain (residues 1–176) of E. coli PS. Here we report the backbone and side-chain assignments for HN, ^{13}C (C^a, C^\beta & CO) and $^{15}N$ nuclei of the protein, obtained using triple resonance NMR experiments (Yamazaki et al., 1994). CSI and NOE data indicates that the protein is well folded containing both \alpha-helices and $_\beta$-sheet. Assignment for \sim 95% of backbone and side-chain resonances for the catalytic domain has been obtained and deposited in BMRB (accession # 6940)

NMR assignment of 2H^2H, 13C^{13}C and 15N^{15}N labeled amino-terminal domain of apo-pantothenate synthetase from E. coli

Pantothenate (vitamin $b_5$) is an essential precursor for the biosynthesis of coenzyme A (CoA), an essential metabolite for many important cellular processes (Brown et al., 1987). Pantothenate Synthetase (PS) catalyzes the ATP dependent condensation of D-pantoate with $_\beta$-alanine to give rise to pantothenate. Our interest lies in studying the solution-state inter-domain interactions in E. coli PS that results in formation of the catalytic site. As a first step we have cloned and over-expressed an isotopically enriched sample of the dimeric amino-terminal domain (residues 1–176) of E. coli PS. Here we report the backbone and side-chain assignments for HN, ^{13}C (C^a, C^\beta & CO) and $^{15}N$ nuclei of the protein, obtained using triple resonance NMR experiments (Yamazaki et al., 1994). CSI and NOE data indicates that the protein is well folded containing both \alpha-helices and $_\beta$-sheet. Assignment for \sim 95% of backbone and side-chain resonances for the catalytic domain has been obtained and deposited in BMRB (accession # 6940)

The Coil-to-Helix Transition in IlvN Regulates the Allosteric Control of Escherichia coli Acetohydroxyacid Synthase I

The solution structure of IlvN, the regulatory subunit of Escherichia coil acetohydroxyacid synthase I, in the valine-bound form has been determined using high-resolution multidimensional, multinuclear nuclear magnetic resonance (NMR) methods. IlvN in the presence or absence of the effector molecule is present as a 22.5 kDa dimeric molecule. The ensemble of 20 low-energy structures shows a backbone root-mean-square deviation of 0.73 +/- 0.13 angstrom and a root-mean-square deviation of 1.16 +/- 0.13 angstrom for all heavy atoms. Furthermore, more than 98% of the backbone phi and psi dihedral angles occupy the allowed and additionally allowed regions of the Ramachandran map, which is indicative of the fact that the structures are of high stereochemical quality. Each protomer exhibits a beta alpha beta beta alpha beta alpha topology that is a characteristic feature of the ACT domain seen in metabolic enzymes. In the valine-bound form, IlvN exists apparently as a single conformer. In the free form, IlvN exists as a mixture of conformational states that are in intermediate exchange on the NMR time scale. Thus, a large shift in the conformational equilibrium is observed upon going from the free form to the bound form. The structure of the valine-bound form of IlvN was found to be similar to that of the ACT domain of the unliganded form of IlvH. Comparisons of the structures of the unliganded forms of these proteins suggest significant differences. The structural and conformational properties of IlvN determined here have allowed a better understanding of the mechanism of regulation of branched chain amino acid biosynthesis