Elastin Peptides Research Articles

MMP-14 degrades tropoelastin and elastin

Matrix metalloproteinases are a class of enzymes, which degrade extracellular matrix components such as collagens, elastin, laminin or fibronectin. So far, four matrix metalloproteinases have been shown to degrade elastin and its precursor tropoelastin, namely matrix metalloproteinase-2, -7, -9 and -12. This study focuses on investigating the elastinolytic capability of membrane-type 1 matrix metalloproteinase, also known as matrix metalloproteinase-14. We digested recombinant human tropoelastin and human skin elastin with matrix metalloproteinase-14 and analyzed the peptide mixtures using complementary mass spectrometric techniques and bioinformatics tools. The results and additional molecular docking studies show that matrix metalloproteinase-14 cleaves tropoelastin as well as elastin. While tropoelastin was well degraded, fewer cleavages occurred in the highly cross-linked mature elastin. The study also provides insights into the cleavage preferences of the enzyme. Similar to cleavage preferences of matrix metalloproteinases-2, -7, -9 and -12, matrix metalloproteinase-14 prefers small and medium-sized hydrophobic residues including Gly, Ala, Leu and Val at cleavage site P1’. Pro, Gly and Ala were preferably found at P1-P4 and P2′-P4′ in both tropoelastin and elastin. Cleavage of mature skin elastin by matrix metalloproteinase-14 released a variety of bioactive elastin peptides, which indicates that the enzyme may play a role in the development and progression of cardiovascular diseases that go along with elastin breakdown.

Identification of novel peptides with high stability against in vitro hydrolysis from bovine elastin hydrolysates and evaluation of their elastase inhibitory activity

SummarySurviving in the gastrointestinal tract is crucial for biopeptides to exert physiological effects in vivo. To enrich elastase inhibitory peptides with high digestive stability, elastin peptides was separated by using ultrafiltration and macroporous resin column, then changes in elastase inhibitory activity, amino acid composition and peptide profile of elastin peptides during in vitro digestion were measured. The results revealed that the fraction F3 eluted by 40% ethanol displayed high digestive stability possibly due to the high content of Pro‐containing peptides (20.25%). Particularly, thirty peptides in F3 exhibited high digestive stability and most of them contained GV and/or PG fragment. Since GV and PG could inhibit 35.70% and 51.77% elastase activity at the concentration of 20 mm, respectively, peptides in F3 survived in in vitro digestion which contained GV and PG sequence might be potential elastase inhibitors. This provides an approach for preparation of peptides with high bioactivity and digestive stability.

Role of elastin peptides and elastin receptor complex in metabolic and cardiovascular diseases

The Cardiovascular Continuum describes a sequence of events from cardiovascular risk factors to end-stage heart disease. It includes conventional pathologies affecting cardiovascular functions such as hypertension, atherosclerosis or thrombosis and was traditionally considered from the metabolic point of view. This Cardiovascular Continuum, originally described by Dzau and Braunwald, was extended by O'Rourke to consider also the crucial role played by degradation of elastic fibers, occurring during aging, in the appearance of vascular stiffness, another deleterious risk factor of the continuum. However, the involvement of the elastin degradation products, named elastin-derived peptides, to the Cardiovascular Continuum progression has not been considered before. Data from our laboratory and others clearly showed that these bioactive peptides are central regulators of this continuum, thereby amplifying appearance and evolution of cardiovascular risk factors such as diabetes or hypertension, of vascular alterations such as atherothrombosis and calcification, but also nonalcoholic fatty liver disease and nonalcoholic steatohepatitis. The Elastin Receptor Complex has been shown to be a crucial actor in these processes. We propose here the participation of these elastin-derived peptides and of the Elastin Receptor Complex in these events, and introduce a revisited Cardiovascular Continuum based on their involvement, for which elastin-based pharmacological strategies could have a strong impact in the future.

Lipid Indices, Elastin Turnover and the Development of Microvascular Complications – A Study in Diabetic Patients with Arterial Hypertension

Abstract Background and Aims: An important factor in the development of vascular wall lesions is the degradation of the elastic fiber major protein – elastin. Elastin peptides (EDP) derived from this degradation are present in the circulation and are a stimulus for the production of anti-elastin antibodies (AEAbs) IgM, IgG and IgA. The aim of this study was to investigate the possible association between AEAbs, lipid indices and the development of microvascular complications. Material and Methods: Sera of 93 patients with type 2 diabetes mellitus (T2DM) and arterial hypertension (AH) were investigated (mean age 61,4 ± 11,3 years, diabetes duration 9,88 ± 3,12 years; hypertension duration 9,28 ± 4,98). ELISA was used for determination of anti-elastin antibodies. These levels were compared to serum AEAbs in 42 age- and sex-matched controls. Diabetic patients were divided in two groups according to the presence – Group 1 (n = 67) or absence – Group 2 (n = 26) of microangiopathy. The lipid profile and lipid indices (log TG/HDL, LDL/HDL, TC/HDL and TG/HDL) were also studied. Results: Patients with T2DM and AH showed statistically significant higher levels of serum AEAbs IgA than healthy controls – 0,338 (0,133÷0,452) vs. 0,006 (0,052÷0,068) (KW = 19,54; P < 0.0001). Group 1 showed statistically significant higher levels of AEAbs IgA than patients without microangiopathy – 0,353 (0,173÷0,471) vs. 0,235 (0,098÷0,377) (KW = 3,36; p = 0.05) and healthy controls – 0,353 (0,173÷0,471) vs. 0,006 (0,052÷0,068) (KW = 20,37; p < 0,0001) (0.37 ± 0,03 vs. 0.06÷0.01) (p = 0.0001). Patients from Group 2 showed significantly higher levels of AEAbs IgA than controls 0,235 (0,098÷0,377) vs. 0,006 (0,052÷0,068) (KW = 8,54; P = 0.003). AEAbs IgA showed correlation with insulin dose (r = −0.35); (p = 0.01), SBP (r = 0.31); (p = 0.001), HbA1c (r = 0.21); (p = 0.04), BMI (r = 0.22); (p = 0.01). AEAbs IgA correlated with log TG/HDL (r = 0.28); (p = 0.001), LDL/HDL (r = 0.22); (p = 0.01) TC/HDL (r = 0.22); (p = 0.01) and with TG/HDL (r = 0.15); (p = 0.05). Conclusion: Our study proved a relationship between elevation of AEAb IgA, high lipid indices and the development of microvascular complications in patients with type 2 diabetes mellitus and arterial hypertension.

Impact of aging on inflammatory and immune responses during elastin peptide-induced murine emphysema

Deterioration of lung functions and degradation of elastin fibers with age are accelerated during chronic obstructive pulmonary disease (COPD). Excessive genesis of soluble elastin peptides (EP) is a key factor in the pathophysiology of COPD. We have previously demonstrated that 6-wk-old mice exhibited emphysematous structural changes associated with proinflammatory immune response after EP instillation. In this study, we investigated the consequences of aging on inflammatory, immune, and histological criteria associated with murine emphysema progression after EP exposure. Young (6 wk old) and elderly (15 mo old) C57BL/6J mice were endotracheally instilled with EP, and, at various time points after treatment, the inflammatory cell profiles from bronchoalveolar lavage fluids (BALF) and the T-lymphocyte phenotypes, at local and systemic levels, were analyzed by flow cytometry. Lungs were also prepared to allow morphological and histological analysis by confocal microscopy. Elderly mice exhibited an earlier development of pulmonary emphysema, characterized by an increase of the inflammatory and lymphocytic infiltrates, extracellular matrix breakdown, and airspace enlargement compared with young mice. This age-dependent parenchymal tissue remodeling was associated with an increase of the matrix metalloproteinase expressions and desmosine levels in BALF and/or sera of EP-treated mice. In addition, both the proportion of CD4+CD28- and CD8+CD28- T cells in the tissues of EP-treated mice and the interferon-γ levels in the EP-specific memory T-cell clones were significantly higher in elderly versus younger mice. This study demonstrates that aging accelerates emphysema development and that this effect is linked to increased EP production and their effects on inflammatory and immune response.

Protective Effect of Bovine Elastin Peptides against Photoaging in Mice and Identification of Novel Antiphotoaging Peptides.

This study aimed to investigate the protective effects of bovine elastin hydrolysates on UV-induced skin photoaging in mice and to identify the potent antiphotoaging peptides. Results showed that the ingestion of elastin peptides could obviously ameliorate epidermis hyperplasia and fibroblast apoptosis, and increase the content of hydroxyproline and water in photoaging skin in vivo ( p < 0.05). Furthermore, four peptides with elastase inhibitory activity were purified and identified, including GLPY, PY, GLGPGVG, and GPGGVGAL. Interestingly, GLPY and GPGGVGAL exhibited the highest inhibition activity with 58.77% and 42.91% at 10 mΜ, respectively. This might be attributed to the N-terminal Gly, C-terminal Leu, and Pro at the third position of the N-terminus, which showed stronger affinity and interaction with elastase. Moreover, GLPY and GPGGVGAL could also inhibit the apoptosis of fibroblasts effectively at 50 μΜ ( p < 0.01). It suggested that elastin peptides had great potential to prevent and regulate skin photoaging.

The inflammatory response of elastin peptides in chronic obstructive pulmonary disease

The inflammatory response of elastin peptides in chronic obstructive pulmonary disease

Abstract 109: Exosomes from Mesenchymal Stem Cells Suppress Aortic Elastin Induced Inflammation in Macrophages

Introduction: Mesenchymal Stem Cells (MSCs) from bone marrow have been shown to attenuate aortic aneurysm formation in a variety of rodent models. These effects appear to rely on modulation of systemic inflammation, including the attenuation of macrophage mediated inflammation. Elastin appears to play a significant role in inducing this inflammation and stimulating macrophages to express an M1 phenotype. Here we evaluate the effects human elastin and elastin break down products on macrophage phenotype. We also evaluate the role of human exosomes derived from MSCs on modulating the effect of elastin on macrophage phenotype. Methods: Human peripheral blood monocytes were collected and cultured for six days to isolate human macrophages. The cells were then treated with digested elastin from human aortic tissue or the human peptide VGVAPG in combination with human MSCs or exosomes derived from human MSCs. The phenotype of the macrophages was then analyzed using enzyme linked immune sandwich assays for tumor necrosis factor alpha (TNF-a) secretion, quantitative real time PCR and flow-cytometry for cellular proteins. Results: Macrophages cultured with digested elastin from aortic tissue showed a significant dose response increase in TNF-a production and cell surface markers consistent with an M1 phenotype. In addition, transcripts for pro-inflammatory cytokines significantly increased after exposure to digested elastin. Similar results were obtained using the elastin peptide sequence VGVAPG. Co-culture with MSCs significantly attenuated elastin induced macrophage TNF-a production, production of pro-inflammatory transcripts and M1 related proteins. When MSC derived exosomes were cultured with macrophages, pro-inflammatory markers and TNF-a production was reduced below baseline levels, even after stimulation with elastin peptide. Conclusions: Macrophages develop an M1 phenotype in response to digested aortic elastin and elastin derived peptides. This response is significantly attenuated by exosomes derived from human MSCs

Structural characterization and in vivo pro-tumor properties of a highly conserved matrikine.

Elastin-derived peptides (EDPs) exert protumor activities by increasing tumor growth, migration and invasion. A number of studies have highlighted the potential of VGVAPG consensus sequence-derived elastin-like polypeptides whose physicochemical properties and biocompatibility are particularly suitable for in vivo applications, such as drug delivery and tissue engineering. However, among the EDPs, the influence of elastin-derived nonapeptides (xGxPGxGxG consensus sequence) remains unknown. Here, we show that the AGVPGLGVG elastin peptide (AG-9) present in domain-26 of tropoelastin is more conserved than the VGVAPG elastin peptide (VG-6) from domain-24 in mammals. The results demonstrate that the structural features of AG-9 and VG-6 peptides are similar. CD, NMR and FTIR spectroscopies show that AG-9 and VG-6 present the same conformation, which includes a mixture of random coils and β-turn structures. On the other hand, the supraorganization differs between peptides, as demonstrated by AFM. The VG-6 peptide gathers in spots, whereas the AG-9 peptide aggregates into short amyloid-like fibrils. An in vivo study showed that AG-9 peptides promote tumor progression to a greater extent than do VG-6 peptides. These results were confirmed by in vitro studies such as 2D and 3D proliferation assays, migration assays, adhesion assays, proteinase secretion studies and pseudotube formation assays to investigate angiogenesis. Our findings suggest the possibility that the AG-9 peptide present in patient sera may dramatically influence cancer progression and could be used in the design of new, innovative antitumor therapies.

The Liquid-Like Structure of Elastin

The protein elastin imparts extensibility, elastic recoil, and resilience to tissues including arterial walls, skin, lung alveoli, and the uterus. Elastin and elastin-like peptides are hydrophobic, disordered, and undergo liquid-liquid phase separation upon self-assembly. Despite extensive study, the structure of elastin remains controversial. We use molecular dynamics simulations on a massive scale to elucidate the structural ensemble of aggregated elastin-like peptides. Consistent with the entropic nature of elastic recoil, the aggregated state is stabilized by the hydrophobic effect. However, self-assembly does not entail formation of a hydrophobic core. The polypeptide backbone forms transient, sparse hydrogen-bonded turns and remains significantly hydrated even as self-assembly triples the extent of nonpolar side-chain contacts. Individual chains in the assembly approach a maximally-disordered, melt-like state which may be called the liquid state of proteins. These findings resolve long-standing controversies regarding elastin structure and function and afford insight into the phase separation of disordered proteins.

Degradation of tropoelastin and skin elastin by neprilysin

Neprilysin is also known as skin fibroblast-derived elastase, and its up-regulation during aging is associated with impairments of the elastic fiber network, loss of skin elasticity and wrinkle formation. However, information on its elastase activity is still limited. The aim of this study was to investigate the degradation of fibrillar skin elastin by neprilysin and the influence of the donor's age on the degradation process using mass spectrometry and bioinformatics approaches. The results showed that cleavage by neprilysin is dependent on previous damage of elastin. While neprilysin does not cleave young and intact skin elastin well, it degrades elastin fibers from older donors, which may further promote aging processes. With regards to the cleavage behavior of neprilysin, a strong preference for Gly at P1 was found, while Gly, Ala and Val were well accepted at P1′ upon cleavage of tropoelastin and skin elastin. The results of the study indicate that the progressive release of bioactive elastin peptides by neprilysin upon skin aging may enhance local tissue damage and accelerate extracellular matrix aging processes.

The liquid structure of elastin.

The protein elastin imparts extensibility, elastic recoil, and resilience to tissues including arterial walls, skin, lung alveoli, and the uterus. Elastin and elastin-like peptides are hydrophobic, disordered, and undergo liquid-liquid phase separation upon self-assembly. Despite extensive study, the structure of elastin remains controversial. We use molecular dynamics simulations on a massive scale to elucidate the structural ensemble of aggregated elastin-like peptides. Consistent with the entropic nature of elastic recoil, the aggregated state is stabilized by the hydrophobic effect. However, self-assembly does not entail formation of a hydrophobic core. The polypeptide backbone forms transient, sparse hydrogen-bonded turns and remains significantly hydrated even as self-assembly triples the extent of non-polar side chain contacts. Individual chains in the assembly approach a maximally-disordered, melt-like state which may be called the liquid state of proteins. These findings resolve long-standing controversies regarding elastin structure and function and afford insight into the phase separation of disordered proteins.

Aortic microcalcification is associated with elastin fragmentation in Marfan syndrome.

Marfan syndrome (MFS) is a connective tissue disorder in which aortic rupture is the major cause of death. MFS patients with an aortic diameter below the advised limit for prophylactic surgery (<5 cm) may unexpectedly experience an aortic dissection or rupture, despite yearly monitoring. Hence, there is a clear need for improved prognostic markers to predict such aortic events. We hypothesize that elastin fragments play a causal role in aortic calcification in MFS, and that microcalcification serves as a marker for aortic disease severity. To address this hypothesis, we analysed MFS patient and mouse aortas. MFS patient aortic tissue showed enhanced microcalcification in areas with extensive elastic lamina fragmentation in the media. A causal relationship between medial injury and microcalcification was revealed by studies in vascular smooth muscle cells (SMCs); elastin peptides were shown to increase the activity of the calcification marker alkaline phosphatase (ALP) and reduce the expression of the calcification inhibitor matrix GLA protein in human SMCs. In murine Fbn1C1039G/+ MFS aortic SMCs, Alpl mRNA and activity were upregulated as compared with wild-type SMCs. The elastin peptide-induced ALP activity was prevented by incubation with lactose or a neuraminidase inhibitor, which inhibit the elastin receptor complex, and a mitogen-activated protein kinase kinase-1/2 inhibitor, indicating downstream involvement of extracellular signal-regulated kinase-1/2 (ERK1/2) phosphorylation. Histological analyses in MFS mice revealed macrocalcification in the aortic root, whereas the ascending aorta contained microcalcification, as identified with the near-infrared fluorescent bisphosphonate probe OsteoSense-800. Significantly, microcalcification correlated strongly with aortic diameter, distensibility, elastin breaks, and phosphorylated ERK1/2. In conclusion, microcalcification co-localizes with aortic elastin degradation in MFS aortas of humans and mice, where elastin-derived peptides induce a calcification process in SMCs via the elastin receptor complex and ERK1/2 activation. We propose microcalcification as a novel imaging marker to monitor local elastin degradation and thus predict aortic events in MFS patients. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Hydrophobic Magnetic Nanoparticle Assisted One‐Pot Liquid‐Phase Peptide Synthesis

Chemically stable hydrophobic magnetic nanoparticles were prepared by using an isocyanate as an anchoring group and were applied to the soluble tag‐assisted liquid‐phase peptide synthesis of the peptide elastin. Couplings and deprotections were effectively performed in the presence of the nanoparticles, and the desired product was rapidly collected as a “magnetic” precipitate, enabling a one‐pot procedure. Sonication of the nanoparticles significantly suppressed gelation of the reaction mixture, which allowed the highly aggregating elastin peptide to be synthesized in one pot without difficulty.

Remnant Epitope Autoimmunity in Human Abdominal Aortic Aneurysm: A Pilot Study with Elastin Peptides

Abdominal aortic aneurysm (AAA) is a prevalent disease affecting around 5% of the population aged more than 65years. The exact etiology and physiopathology of AAA still raises questions, and elective surgery is currently the only treatment option for this often progressive disease. In this study, we hypothesized and tested a pathophysiological model that depicts AAA as an inflammation-triggered autoimmune disease with remnant vessel wall peptide fragments as the antigen. A pilot study with male AAA patients (n=14) and male controls (n=8) was conducted. In both study groups, peripheral blood monocytes and plasma were separated from whole blood by centrifugation. An ELISpot test was performed on cultured white blood cells for the presence of elastin-specific T-lymphocytes. An Enzyme-linked immuno sorbent assay (ELISA) was performed on plasma for the presence of elastin-specific IgG molecules. ELISpot interferon-gamma secretion in AAA (7.7±9.5%) and control (4.6±3.5%) and ELISA anti-elastin IgG titer in AAA (77.5±17.8%) and control (78.2±31.5%) were not significantly different (P=0.94 and P=0.55, respectively). Both results are expressed as a percentage relative to the respective positive and negative control. The results of our pilot study did not indicate a clear and invariable autoimmune process directed against remnant elastin peptide fragments. Further research into the model mechanics and a possible antigen is still necessary. In the mean time, the model as presented here already offers a pathophysiological framework to further research into the possible remnant epitope-driven AAA etiology.

Elastin receptor (S-gal) occupancy by elastin peptides modulates T-cell response during murine emphysema.

Chronic obstructive pulmonary disease and emphysema are associated with increased elastin peptides (EP) production because of excessive breakdown of lung connective tissue. We recently reported that exposure of mice to EP elicited hallmark features of emphysema. EP effects are largely mediated through a receptor complex that includes the elastin-binding protein spliced-galactosidase (S-gal). In previous studies, we established a correlation between cytokine production and S-gal protein expression in EP-treated immune cells. In this study, we investigated the S-gal-dependent EP effects on T-helper (Th) and T-cytotoxic (Tc) responses during murine EP-triggered pulmonary inflammation. C57BL/6J mice were endotracheally instilled with the valine-glycine-valine-alanine-proline-glycine (VGVAPG) elastin peptide, and, 21 days after treatment, local and systemic T-lymphocyte phenotypes were analyzed at cytokine and transcription factor expression levels by multicolor flow cytometry. Exposure of mice to the VGVAPG peptide resulted in a significant increase in the proportion of the CD4+ and CD8+ T cells expressing the cytokines IFN-γ or IL-17a and the transcription factors T-box expressed in T cells or retinoic acid-related orphan receptor-γt (RORγt) without effects on IL-4 and Gata-binding protein 3 to DNA sequence [A/T]GATA[A/G] expression. These effects were maximized when each T-cell subpopulation was challenged ex vivo with EP, and they were inhibited in vivo when an analogous peptide antagonizing the EP/S-gal interactions was instilled together with the VGVAPG peptide. This study demonstrates that, during murine emphysema, EP-S-gal interactions contribute to a Th-1 and Th-17 proinflammatory T-cell response combined with a Tc-1 response. Our study also highlights the S-gal receptor as a putative pharmacological target to modulate such an immune response.

Abstract 480: Aortic Microcalcification Associates With Aortic Elastin Fragmentation in Marfan Syndrome

Marfan syndrome (MFS) is a genetic connective tissue disorder, in which aortic rupture is the major cause of death. MFS patients with an aortic diameter below the advised limit for prophylactic surgery (&lt;5cm) may unexpectedly experience an aortic dissection or rupture, despite yearly monitoring. Hence, there is a clear need for improved prognostic markers to predict such aortic events. We hypothesize that elastin fragments play a causal role in aortic calcification in MFS and that microcalcification serves as a novel marker for aortic disease severity. To address this hypothesis, we analyzed MFS patient and mouse aortas. MFS patient aortic tissue showed enhanced microcalcification in areas with extensive elastic lamina fragmentation in the media. A causal relationship between medial injury and microcalcification was revealed by studies in vascular smooth muscle cells (SMCs); elastin peptides were shown to increase the activity of the calcification marker alkaline phosphatase (ALP) and reduce the expression of the calcification inhibitor matrix gla protein (MGP) in human SMCs. In murine Fbn1 C1039G/+ MFS aortic SMCs, ALP mRNA and activity was upregulated when compared to wildtype SMCs. The elastin peptide-induced ALP activity was prevented by incubation with lactose as inhibitor of the elastin receptor complex, and a MEK1/2 kinase inhibitor, indicating downstream involvement of ERK1/2 phosphorylation. Histological analyses in MFS mice revealed macrocalcification in the aortic root, while the ascending aorta contained microcalcification, as identified with the near-infrared fluorescent bisphosphonate probe OsteoSense-800. Significantly, microcalcification correlated strongly with aortic diameter, aortic distensibility, elastin breaks and phosphorylated ERK1/2. In conclusion, microcalcification co-localizes with aortic elastin degradation in MFS aorta of man and mice, where elastin-derived peptides induce a calcification process in SMCs via the elastin receptor complex and ERK1/2 activation. We propose microcalcification as a novel imaging marker to monitor local elastin degradation and thus predict aortic events in MFS patients.

Structure and Self-Assembly of Elastin-Like Peptides: A Joint Molecular Dynamics and NMR Study

Elastin endows tissues such as skin, arterial walls, lung alveoli, and the uterus with extensibility and elasticity. Elastin and elastin-like peptides self-aggregate via a liquid-liquid phase separation process. Although elastin has been the object of biophysical investigation for over eighty years, the structural basis for the self-assembly and the mechanical properties of elastin remains controversial. Elastin is structurally heterogeneous and must be described by an ensemble of structures. As an essential step towards elucidating the structural ensemble of elastin, we combine molecular dynamics simulations and nuclear magnetic resonance (NMR) spectroscopy to study an elastin-like peptide modelled after the sequence of alternating hydrophobic and cross-linking domains of elastin. We perform extensive all-atom molecular dynamics simulations totalling hundreds of microseconds and obtain detailed structural and dynamic data by NMR on the same peptide sequences under the same thermodynamic conditions. Simulation and NMR results are in excellent agreement and show that although the peptide is highly disordered, it possesses a significant propensity for secondary structure. The cross-linking domains are characterized by fluctuating helical structure, whereas the hydrophobic domains adopt fluctuating hydrogen-bonded turns. The latter secondary structure elements are sparse, local, and transient. As a result, the individual domains do not form extensive interactions; they are collapsed but not compact, and they remain disordered and hydrated despite their predominantly hydrophobic character. Taken together, these findings resolve long-standing discrepancies between previous models of the structure and function of elastin. Importantly, these results also afford unprecedented insight into the physical and structural basis for the liquid-liquid phase separation of disordered proteins.

Highly Flexible and Resilient Elastin Hybrid Cryogels with Shape Memory, Injectability, Conductivity, and Magnetic Responsive Properties.

A strategy utilizing elastin peptide macroporous cryogels to build highly flexible scaffolds to load carbon nanotubes, polypyrrole, and iron oxide magnetic nanoparticles, is presented. This combines high elasticity, flexibility, shape memory property, and injectable property together with conductivity and/or magnetic responsive property. The network can afford 97.5% compressive strain with an excellent conductivity of 50.1 ± 2.9 S cm(-1) at 90% strain.

High-molecular-weight poly(Gly-Val-Gly-Val-Pro) synthesis through microwave irradiation

In this study, we synthesized a polypeptide from its pentapeptide unit using microwave irradiation. Effective methods for polypeptide synthesis from unit peptides have not been reported. Here, we used a key elastin peptide, H-GlyValGlyValPro-OH (GVGVP), as the monomer peptide. It is difficult to obtain poly(Gly-Val-Gly-Val-Pro) (poly(GVGVP)) from the pentapeptide unit of elastin, GVGVP, via polycondensation. Poly(GVGVP) prepared from genetically recombinant Escherichia coli is a well-known temperature-sensitive polypeptide, and this temperature sensitivity is known as the lower critical solution temperature. When microwave irradiation was performed in the presence of various additives, the pentapeptide (GVGVP) polycondensation reaction proceeded smoothly, resulting in a product with a high molecular weight in a relatively good yield. The reaction conditions, like microwave irradiation, coupling agents, and solvents, were optimized to increase the reaction efficiency. The product exhibited a molecular weight greater than Mr 7000. Further, the product could be synthesized on a gram scale. The synthesized polypeptide exhibited a temperature sensitivity that was similar to that of poly(GVGVP) prepared from genetically recombinant E. coli. Therefore, this technique offers a facile and quick approach to prepare polypeptides in large amounts. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.