Reversible Photocontrol of Microtubule Stability by Spiropyran-Conjugated Tau-Derived Peptides

Spatiotemporal modulation of microtubules by light has become an important aspect of the biological and nanotechnological applications of microtubules. We previously developed a Tau-derived peptide as a binding unit to the inside of microtubules. Here, we conjugated the Tau-derived peptide to spiropyran, which is reversibly converted to merocyanine by light, as a reversible photocontrol system to stabilize microtubules. Among the synthesized peptides with spiropyran/merocyanine at different positions, several peptides were bound to the inside of microtubules and stabilized the structures of microtubules. The peptide with spiropyran at the N-terminus induced polymerization and stabilization of microtubules, whereas the same peptide with the merocyanine form did not exert these effects. Reversible formation of microtubules/tubulin aggregates was achieved using the peptide with spiropyran conjugated at the N-terminus and irradiation with UV and visible light. Spiropyran-conjugated Tau-derived peptides would be useful for spatiotemporal modulation of microtubule stability through reversible photocontrol of binding.     

Discovery and Biosynthesis of Ureidopeptide Natural Products Macrocyclized via Indole N-acylation in Marine Microbulbifer spp. Bacteria

Commensal bacteria associated with marine invertebrates are underappreciated sources of chemically novel natural products. Using mass spectrometry, we had previously detected the presence of peptidic natural products in obligate marine bacteria of the genus Microbulbifer cultured from marine sponges. In this report, the isolation and structural characterization of a panel of ureidohexapeptide natural products, termed the bulbiferamides, from Microbulbifer strains is reported wherein the tryptophan side chain indole participates in a macrocyclizing peptide bond formation. Genome sequencing identifies biosynthetic gene clusters encoding production of the bulbiferamides and implicates the involvement of a thioesterase in the indolic macrocycle formation. The structural diversity and widespread presence of bulbiferamides in commensal microbiomes of marine invertebrates point toward a possible ecological role for these natural products.     

辣木籽油粕多肽提取工艺及其活性的研究

以辣木籽的副产物辣木籽油粕为原料,采用酶解法提取辣木籽油粕多肽,在单因素试验的基础上,采用响应面试验对蛋白酶酶解提取多肽的工艺进行优化,并对辣木籽油粕多肽的生物活性进行了测定。结果表明,酶解辣木籽油粕的最佳工艺条件为：pH=6.60、酶添加量5200 U/g、酶解温度45.5 ℃、酶解时间5 h,在此条件下,辣木籽油粕多肽提取率为38.64%。此外辣木籽油粕多肽对DPPH、ABTS自由基有很好的清除效果,与Fe2+也具有很好螯合效果,以及对α-葡萄糖苷酶活性有一定的抑制作用。     

Fast Self-Assembly Dynamics of a β-Sheet Peptide Soft Material

Peptide-based hydrogels are promising biocompatible materials for wound healing, drug delivery, and tissue engineering applications. The physical properties of these nanostructured materials depend strongly on the morphology of the gel network. However, the self-assembly mechanism of the peptides that leads to a distinct network morphology is still a subject of ongoing debate, since complete assembly pathways have not yet been resolved. To unravel the dynamics of the hierarchical self-assembly process of the model β-sheet forming peptide KFE8 (Ac-FKFEFKFE-NH₂)_, high-speed atomic force microscopy (HS-AFM) in liquid is used. It is demonstrated that a fast-growing network, based on small fibrillar aggregates, is formed at a solid–liquid interface, while in bulk solution, a distinct, more prolonged nanotube network emerges from intermediate helical ribbons. Moreover, the transformation between these morphologies has been visualized. It is expected that this new in situ and in real-time methodology will set the path for the in-depth unravelling of the dynamics of other peptide-based self-assembled soft materials, as well as gaining advanced insights into the formation of fibers involved in protein misfolding diseases.     

New insights into the cholesterol esterase- and lipase-inhibiting potential of bioactive peptides from camel whey hydrolysates: Identification,characterization, and molecular interaction

Novel antihypercholesterolemic bioactive peptides (BAP) from peptic camel whey protein hydrolysates (CWPH) were generated at different time, temperature, and enzyme concentration (%). Hydrolysates showed higher pancreatic lipase- (PL; except 3 CWPH) and cholesterol esterase (CE)-inhibiting potential, as depicted by lower half-maximal inhibitory concentration values (IC₅₀ values) compared with nonhydrolyzed camel whey proteins (CWP). Peptide sequencing and in silico data depicted that most BAP from CWPH could bind active site of PL, whereas as only 3 peptides could bind the active site of CE. Based on higher number of reactive residues in the BAP and greater number of substrate binding sites, FCCLGPVPP was identified as a potential CE-inhibitory peptide, and PAGNFLPPVAAAPVM, MLPLMLPFTMGY, and LRFPL were identified as PL inhibitors. Molecular docking of selected peptides showed hydrophilic and hydrophobic interactions between peptides and target enzymes. Thus, peptides derived from CWPH warrant further investigation as potential candidates for adjunct therapy for hypercholesterolemia.     

Stability to thermal treatment of dipeptidyl peptidase-IV inhibitory activity of a boarfish (Capros aper) protein hydrolysate when incorporated into tomato-based products

Biofunctional peptide ingredients should retain their stability following standard processing operations in food-based delivery vehicles. A boarfish protein hydrolysate, exhibiting anti-diabetic activity, was subjected to a range of thermal treatments following incorporation into tomato-based soup and juice products. The dipeptidyl peptidase-IV (DPP-IV) inhibitory activity and peptide profile of the hydrolysate within the products were assessed before and after thermal treatment. The treatments applied had no effect on the DPP-IV inhibitory activity or peptide profile of the protein hydrolysate. The heat-treated (90 °C × 1 min and 121 °C × 42 s) juice-fortified beverage had microbial counts within the acceptable limits for consumption when stored at 4 °C for 30 days. Furthermore, the hydrolysate within the beverage products was resistant to simulated gastrointestinal digestion (SGID) regardless of whether it was heat- or non-heat-treated, or stored for 30 days at 4 °C. Therefore, tomato-based beverages are suitable delivery vehicles for biofunctional peptide ingredients.     

大孔树脂分离红花籽粕酶解产物制备抗氧化肽的工艺研究

为制备红花籽粕抗氧化活性肽,比较不同酶解工艺下产物的抗氧化性,研究AB-8大孔树脂分离工艺,对比分离前后多肽抗氧化性,结果表明:碱性蛋白酶Alcalase酶解产物抗氧化性最佳,测得还原力为1.755,DPPH自由基清除率39.84％,羟自由基清除率26.76％、超氧阴离子自由基清除率25.90％,多肽含量达到10.71...     

Viral Transduction Enhancing Effect of EF-C Peptide Nanofibrils Is Mediated by Cellular Protrusions

Self-assembling peptide nanofibrils (PNF) have gained increasing attention as versatile molecules in material science and biomedicine. One important application of PNF is to enhance retroviral gene transfer, a technology that has been central for gene therapy approaches. The best-investigated and commercially available PNF is derived from a 12-mer peptide termed EF-C. The mechanism of transduction enhancement depends on the polycationic surface of EF-C PNF, which bind to the negatively charged membranes of viruses and cells, thereby overcoming electrostatic repulsions and increasing virion attachment and fusion. To better understand how EF-C PNF interact with the cell surface, scanning electron and time-lapse confocal microscopy were performed. The fibrils are found to be actively engaged by cellular protrusions such as filopodia. Consequently, chemical suppression of protrusion formation abrogates fibril binding and virion delivery to the cell surface of immortalized and primary T cells. Vice versa, induction of plasma membrane blebs result in increased fibril binding. Thus, the mechanism of PNF-mediated viral transduction enhancement involves an active engagement of virus-loaded fibrils by cellular protrusions, which may explain its superior performance over soluble transduction enhancers.     

Engineering Next Generation Cyclized Peptide Ligands for Light-Controlled Capture and Release of Therapeutic Proteins

Photo-affinity adsorbents (i.e., translucent matrices functionalized with ligands featuring light-controlled biorecognition) represent a futuristic technology for purifying labile biologics. In this study, a framework for prototyping photo-affinity adsorbents comprising azobenzene-cyclized peptides (ACPs) conjugated to translucent porous beads (ChemMatrix) is presented. This approach combines computational and experimental tools for designing ACPs and investigating their light-controlled isomerization kinetics and protein biorecognition. First, a modular design for tailoring ACP's conformation, facilitating sequencing, and streamlining the in silico modeling of cis/trans isomers and their differential protein binding is introduced. Then, a spectroscopic system for measuring the photo-isomerization kinetics of ACPs on ChemMatrix beads is reported; using this device, it is demonstrated that the isomerization at different light intensities is correlated to the cyclization geometry, specifically the energy difference of trans versus cis isomers as calculated in silico. Also, a microfluidic device for sorting ACP-ChemMatrix beads to select and validate photo-affinity ligands using Vascular Cell Adhesion Molecule 1 (VCAM-1) as target protein and cyclo_AZOB[GVHAKQHRN-K*]-G-ChemMatrix as model photo-affinity adsorbent is presented. The proposed ACPs exhibit rapid and defined light-controlled isomerization and biorecognition. Controlling the adsorption and release of VCAM-1 using light demonstrates the potential of photo-affinity adsorbents for targets whose biochemical liability poses challenges to its purification.