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The endostatin protein is a potent inhibitor of angiogenesis and tumor growth. The anti-angiogenic and antitumor properties of full-length endostatin can be mimicked by its N-terminal segment, including residues 1-27. Therefore, our previous studies have shown that a mutant N-terminal peptide which the Zn-binding loop was replaced by a disulfide loop (referred to as the ES-SS peptide) has preserved antiangiogenic and antitumor properties compared to the native peptide. To increase stability and plasma half-life of the ES-SS peptide, the nano-sized liposomal formulations of the peptide with different ratio of phosphocholine (PC) were synthesized. The liposomal peptide formulations possessed an average size of around 100 nm with (-4 to -36 mv) in zeta potential. The encapsulation efficiency of the ES-SS peptide was in the range of 24-54% with different lipid: peptide molar ratios. In vitro release of the peptide from liposomes indicated a complete peptide release after 7 days. Cytotoxicity assay was evaluated using the human umbilical vein endothelial cells (HUVECs) for various concentrations of the liposomal peptide. The results depicted the gradual release of the peptide through liposomes. By comparing with the free peptide, the liposomal peptide formulations have indicated higher cell viability with IC 50 value about 0.1 μM. The peptide-liposome interactions, as well as the peptide effect on the liposome structure, were also investigated through coarse-grained molecular dynamics (CG-MD) simulation. The results revealed that the peptides were assembled in the hydrophilic core of the liposome. The peptide behavior in liposome can stabilize the liposome structure and be a response to the observed low peptide release rate. The investigation is promising for designing a liposome-based anti-angiogenesis peptide delivery system., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A natural peptide motif in the first helix of osteocalcin (OCN) is used to promote nucleation and crystallization of hydroxyapatite (HA) in hard tissue. The capability of osteocalcin mimetic peptides to induce osteogenic activity of osteoblast cells leading to in-vitro mineralization is demonstrated. An osteocalcin-derived peptide consisting of thirteen amino acids is synthesized in both acidic (OSC) and amidic (OSN) forms and added into the human osteoblast-like cells (MG63) culture. The viability, proliferation, alkaline phosphatase activity, HA deposition and osteogenic gene expression by osteoblast cells are evaluated. It is revealed that the addition of 100 μg/ml of peptides enhances the proliferation rate and total protein content of osteoblast cells. Alkaline phosphatase activity is significantly higher in the presence of peptides which in turn stimulated RNA expression of collagen type I and osteopontin in a phosphate-dependent manner. Alizarin red staining and calcium content measurement show that mineral deposition is considerably increased. Ultrastructural characterization of MG63 cultures confirms the crystalline nature and chemical composition of HA mineral formation in the presence of peptides. It is confirmed that the osteocalcin-derived peptide, particularly in amidic form (OSN), is able to act as a bioactive inducer of mineralization process and hence accelerating bone tissue regeneration., (Copyright © 2018. Published by Elsevier B.V.)

Expansion of human induced pluripotent stem cells (h-iPSCs) on mouse derived feeder layers or murine cells secretions such as Matrigel hamper their clinical applications. Alternative methods have introduced novel substrates as stem cell niches or/and optimized combinations of humanized soluble factors as fully defined mediums. Accordingly vitronectin as a main part of ECM have been commercialized significantly as a stem cell niche-forming substrate. In this work, we used a functional peptide derived from vitronectin (VTN) and co-immobilized it with FGF-2 (as an indisputable ingredient of defined culture mediums) on chitosan film surface. After chemical and physical characterization of the pristine chitosan surface as well as ones modified by VTN or/and FGF-2, h-iPS cells were cultured on them at the xeno/feeder-free conditions. Our results demonstrated that co-immobilization of these two biomolecules has a synergistic effect on adhesion and clonal growth of h-iPS cells with maintained expression of pluripotency markers in a FGF-2 density-dependent manner. This is the first report of co-immobilization of an ECM derived molecule and a growth factor for stem cell culture., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The selective toxicity of depressant scorpion neurotoxins to insects is useful in studying the insect sodium channel gating, as well as being relevant to several other applications. In order to carry out structure/activity studies, the functional expression of such polypeptides is required. In the work reported here, the cDNA of a new peptide from the venom of the scorpion Buthotus saulcyi was cloned and sequenced. It codes for a 64 residues peptide (BsaulI) with 8 highly-conserved cysteines. This peptide shares high sequence similarity with depressant insect toxins of other scorpion species. Large amounts of insoluble BsaulI protein were expressed in Escherichia coli. Purification of this peptide was carried out under denaturing conditions. Renaturation was performed by pulsed dilution of the denatured BsaulI in the refolding buffer. Production of refolded Bsaul1, however, is approximately an order of magnitude higher than that obtained with similar scorpion depressant toxins. Intrinsic fluorescence, far-UV circular dichroism spectra and biological activity assays indicate that the peptide adopts a folded structure.

Aurein1.2 is a cationic peptide with antimicrobial and anticancer activity. In order to find a novel peptide with this activity, aurein1.2 was utilized as a template and the sequences were designed by a RosettaDesign server with our proposed pattern. As a result, tempY was designed and synthesized, and its structural and biological activity was investigated. TempY has a sequence similar to that of the temporins group but with potent antibacterial properties against Gram-positive bacteria and effective anticancer activity (LC is 20-30 μg/ml). This latter activity may be due to the tyrosine at the C terminus of the peptide. Kar peptide is another model derived from the complete design of aurein1.2. Kar is only active against A549 cells. The net charge of Kar is four, and it is inactive against Gram-positive bacteria and MCF-7 cells, which may be due to the high positive-charge density on the surface of peptide. [ABSTRACT FROM AUTHOR]

A novel peptide, PNP (Pseudocerastes persicus natriuretic peptide), was isolated from the venom of the Iranian viper P. persicus. Amino acid sequencing revealed that the 37-residue peptide belongs to the family of natriuretic peptides. The physiological effects of intra-venously PNP infused into anesthetized rats on urine flow, sodium excretion and blood pressure were comparable to those of atrial natriuretic peptide (ANP). In PC12 cells that were treated with either PNP, ANP, or C-type natriuretic peptide, PNP induced a similar cGMP response as ANP. Since PC12 cells only express the natriuretic peptide receptor (NPR)-A receptor we conclude that PNP binds to the NPR-A receptor. The solution conformation of PNP was characterized using 1H nuclear magnetic resonance spectroscopy and indicates a high degree of conformational flexibility. [Copyright &y& Elsevier]