Aminos?uren und Peptide

Zusammenfassung Es kann festgestellt werden, daß auf dem Gebiet der Analyse der Aminosäuren und Peptide neue Methoden entwickelt wurden, die dem Biochemiker und dem organischen Chemiker die Lösung verschiedenartigster Probleme erleichtern.

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Summary A survey is given of the analytical methods available for amino-acids and peptides and it is shown that several new procedures have been developed which can be successfully employed for solving various problems.

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Meinen Mitarbeitern, vor allem Herrn Dr. A. Prox, gilt mein aufrichtiger Dank für intensive Bemühungen; der Deutschen Forschungsgemeinschaft und dem Bundesministerium für Wissenschaftliche Forschung danke ich für die Unterstützung dieser Arbeiten.     

Supramolecular Chemistry of Peptide Bundles

Amphiphilic octadecapeptides containing 8～9 leucines in the hydrophobic phase wete syn-thesized and shown to self-associate to form α-helical hexamers. The NMR spectra of molecular com-plexes from such peptides and substrate 1 showed that these hexamers exist as a twisted helical bundlecontaining an annular space in its middle.     

Searching for Peptide Ligands of Interleukin-2 Receptor α Chain in Phage-displayed Peptide Library

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A Novel Peptide from Buthus martensii Karch

A novel peptide was purified and characterized from Buthus martensii Karch.The peptide,named BmK M6,is a single-chain polypeptide cross-linked by four intramolecular disulfide bridges.The molecular weight of the peptide was determined by MOLDI-TOF-MS as 7034 Da.The partial amino acid sequence of BmK M6 from N-terminal is VRDAYIAKPEN CVYECGITQDCNKLCTENG.     

A New Cyclic Peptide from Schnabelia tetradonta

A new cyclic octapeptide (schnabepeptide B) was isolated from the aerial part of Schnabelia tetradonta (Sun) C. Y. Wu et C. Chert (Lamiaceae). Its structure was elucidated as cyclo-(NH-Trp-Gly1-Leu1-Gly2-Pro1-Pro2-Leu2-Pr03-CO) on the basis of extensive 2D NMR and MS spectra.     

Construction and Analysis of N-phosphoryl Peptide Libraries

N-Phosphoryl peptide libraries were constructed by transformation from homo-oligopeptide libraries, which was synthesized by self-assembly of amino acids with the assistance of phosphorus oxychloride. Electrospray ionization mass spectrometry (ESI-MS) was used to monitor the reaction.     

Binding Mode of Insulin Receptor and Agonist Peptide

LI Wei Introduction In1986,Geysen[1]foundthatshortpeptidescon tainingthekeyresiduesofaproteincanmimicthede terminantoftheprotein;mostofthebindingenergybe tweenproteinsresultsfromthenoncovalentinteractions ofsomekeyresidues.Thesesmallpeptidesgenerally have…     

Role of Regulatory Peptide in Pathogenesis of Shock

The present study evaluated the pathogenetic roles of three kinds of regulatory peptide. The results showed that (i) plasma endothelin(ET) level elevated significantly in septic shock rats, persistent intravenous drip of low doses ET caused development of shock state in normal rats and the irreversible outcome of light hemorrhagic shock. Furthermore, i. v. administration of specific ET-antiserum was significantly effective to septic shock rats, (Ⅱ) Plasma calcitonin gene-related peptide (CGRP) increased by 260% in septic shock rats, i. v. drip of low doses CGRP both in early and late sepsis were effective to shock rats, (Ⅱi) An-giotensin-Ⅱ (ANG-Ⅱ) contents of heart and aorta increased dramatically both in early and late septic shock, and inhibiting its increase with Captopril in late sepsis significantly improved the shock state, but results were inverse in early sepsis. It could be concluded that ET was one of the most important factors participating in the pathogenesis of shock, CGRP had a compens     

Selection of Peptide Ligands Specific for Baculovirus DNA‐Binding Protein from the Flitrx™ Random Peptide Display Library

Abstract

Autographa californica nucleopolyhedrovirus (AcNPV) is a baculovirus that is widely employed as a vector for the expression of foreign genes and pest control. Although baculoviruses, including AcNPV, efficiently replicate in the nuclei of arthropod cells, the dynamics and mechanism of DNA replication within the infected cell are still poorly understood. It has been found that the DNA‐binding protein (DBP) is an early gene product and appears to be crucial for viral DNA replication.

Presented here is the selection of peptide ligands that specifically bind to DBP for AcNPV from the FliTrx? random peptide display library; this entails the amplification, cloning of the DNA‐binding protein (DBP) gene from AcNPV and the construction of the expression plasmid for DBP, and the expression and purification of the recombinant His.Tag AcNPV DBP that was used as a target molecule for the selection of the peptide ligands specific for AcNPV DBP. The affinity and efficiency of such peptide ligands were then measured by ELISA procedures.

The beneficial aspect of this research is the monospecificity quality of the peptide ligands specific for AcNPV DBP. They could be used for the study of the dynamics of the viral genome and its replication within the infected cell, for the development of a quantitative method for the determination of the presence of baculovirus in various samples, for the development of a peptide ligandbased assay for the determination of baculovirus titers; or they could be immobilized on a chromatographic support for an improved affinity purification of AcNPV DBP.     

Peptide/laccase cocatalyzed asymmetric α-oxyamination of aldehydes

An asymmetric α-oxyamination could be successfully performed by a peptide catalyst and laccase. The combination of peptide catalysis and enzymatic air oxidation promoted the reaction smoothly in water without employing a metal reagent. The oxyaminated compounds could be obtained as both aldehyde and carboxylic acid products depending on the reaction conditions.     

Gold Ion–Angiotensin Peptide Interaction by Mass Spectrometry

Stimulated by the interest in developing gold compounds for treating cancer, gold ion–angiotensin peptide interactions are investigated by mass spectrometry. Under the experimental conditions used, the majority of gold ion–angiotensin peptide complexes contain gold in the oxidation states I and III. Both ESI-MS and MALDI-TOF MS detect singly/multiply charged ions for mononuclear/multinuclear gold-attached peptides, which are represented as [peptide + a Au(I) + b Au(III) + (e - a -3b) H]^e+, where a,b ≥ 0 and e is charge. ESI-MS data shows singly/multiply charged ions of Au(I)-peptide and Au(III)-peptide complexes. This study reveals that MALDI-TOF MS mainly detects singly charged Au(I)-peptide complexes, presumably due to the ionization process. The electrons in the MALDI plume seem to efficiently reduce Au(III) to Au(I). MALDI also tends to enhance the higher polymeric forms of gold-peptide complexes regardless of the laser power used. Collision-induced dissociation experiments of the mononuclear and dinuclear gold-attached peptide ions for angiotensin peptides show that the gold ion (a soft acid) binding sites are in the vicinity of Cys (a soft ligand), His (a major anchor of peptide for metal ion chelation), and the basic residue Arg. Data also suggests that the abundance of gold-attached peptides increases with higher gold concentration until saturation, after which an increase in gold ion concentration leads to the aggregation and/or precipitation of gold-bound peptides.     

Peptide Chirality Sensing by a Cyclodextrin–Polythiophene Conjugate

A new cyclodextrin–polythiophene conjugate ( CDPT ) has been prepared by attaching permethyl-α-cyclodextrins to polythiophene (PT) through a hexamethylene tether. Circular dichroism spectral examination of CDPT revealed that only a weak positive Cotton effect (Δε=0.1 M ⁻¹ cm⁻¹) was induced at the main band of the PT in dimethyl sulfoxide and similarly weak bisignate signals in pure and aqueous methanol solutions, which indicates that the α-cyclodextrins appended to PT with a long tether are ineffective in inducing a homochiral structure in the PT backbone. Nevertheless, enantiomeric amino acids and dipeptides added to an aqueous methanolic solution of CDPT caused chirality-dependent hypochromic changes in the UV/Vis spectra, which enabled us to sense these species and quantitatively determine the enantioselectivity by observing the difference in absorbance upon interaction with pairs of enantiomers. Enantiomeric d,d /l,l -dipeptide pairs rather than D /L -amino acid pairs were better differentiated in general, the highest dd /ll selectivity of 13.7 being observed for Phe-Phe.     

Peptide asparaginyl ligases——renegade peptide bond makers

Making peptide bonds is tightly controlled by genetic code and machinery which includes cofactors,ATP,and RNAs.In this regard,the stand-alone and genetic-code-independent peptide ligases constitute a new family of renegade peptide-bond makers.A prime example is butelase-1,an Asn/Asp(Asx)-specific ligase that structurally belongs to the asparaginyl endopeptidase family.Butelase-1 specifically recognizes a C-terminal Asx-containing tripeptide motif,Asn/Asp-Xaa-Yaa(Xaa and Yaa are any amino acids),to form a site-specific Asn-Xaa peptide bond either intramolecularly as cyclic proteins or intermolecularly as modified proteins.Our work in the past five years has validated that butelase-1 is a potent and versatile ligase.Here we review the advances in ligases,with a focus on butelase-1,and their applications in engineering bioactive peptides and precision protein modifications,antibody-drug conjugates,and live-cell labeling.     

Über die beim tryptischen Abbau von Pferde-Cytochromc entstehenden Peptide

Zusammenfassung Die bei tryptischer Spaltung von Pferde-Cytochromc entstehenden Peptide wurden mit Hilfe papierelektrophoretischer und papierchromatographischer Methoden isoliert und ihre Aminosäuresequenz bestimmt. Damit wurde eine wichtige Voraussetzung für die Ermittlung der gesamten Struktur des Cytochromsc erfüllt⁴⁰. Besonders interessant war der Befund, daß eines der tryptischen Peptide, das offenbar vom Aminoende der Polypeptidkette des Cytochrom-c-Apoproteins stammt, einen acetylierten N-terminalen Aminosäurerest enthält.Mit 3 Abbildungen     

All-d-Enantiomer of β-Amyloid Peptide Forms Ion Channels in Lipid Bilayers

Alzheimer's disease (AD) is the most common type of senile dementia in aging populations. Amyloid β (Aβ)-mediated dysregulation of ionic homeostasis is the prevailing underlying mechanism leading to synaptic degeneration and neuronal death. Aβ-dependent ionic dysregulation most likely occurs either directly via unregulated ionic transport through the membrane or indirectly via Aβ binding to cell membrane receptors and subsequent opening of existing ion channels or transporters. Receptor binding is expected to involve a high degree of stereospecificity. Here, we investigated whether an Aβ peptide enantiomer, whose entire sequence consists of d-amino acids, can form ion-conducting channels; these channels can directly mediate Aβ effects even in the absence of receptor-peptide interactions. Using complementary approaches of planar lipid bilayer (PLB) electrophysiological recordings and molecular dynamics (MD) simulations, we show that the d-Aβ isomer exhibits ion conductance behavior in the bilayer indistinguishable from that described earlier for the l-Aβ isomer. The d isomer forms channel-like pores with heterogeneous ionic conductance similar to the l-Aβ isomer channels, and the d-isomer channel conductance is blocked by Zn(2+), a known blocker of l-Aβ isomer channels. MD simulations further verify formation of β-barrel-like Aβ channels with d- and l-isomers, illustrating that both d- and l-Aβ barrels can conduct cations. The calculated values of the single-channel conductance are approximately in the range of the experimental values. These findings are in agreement with amyloids forming Ca(2+) leaking, unregulated channels in AD, and suggest that Aβ toxicity is mediated through a receptor-independent, nonstereoselective mechanism.     

Small Peptide Interacting with Pollen Calmodulinand their Effects on Cellular Functions

Calmodulin(CaM),asmallCa' -bindingproteininalleukaryoticorganisms,regulatesmanydifferentiatedfunctionsincellthroughmodulationofCa2 signalsandinteractionWithsomeimportantenZymes.Althoughtheaminoacidsequencesofcalmlodulinsfromdifferentspeciesarehighlyconserved',therearesomedistinctionsintheirproperties'.UPtonoW,animalCaMshavealwaysbeenusedtostudytheinteractionofthisproteinwithtargetpeptidessoastofindefficientCaMantagonists.Inthisreport,thediscoveryofsynthesizedpeptides'bindingtorapepollenca…     

Synthesis of New Chiral Building Blocks for Novel Peptide Nucleic Acids

IntroductionAbouttenyearsago ,PNA ,astructuralmimicofDNAinwhichthesugar phosphatebackboneisreplacedbyN (2 aminoethyl)glycine (aeg)linkageemergedasapotentialanti sensetherapeuticagent.1PNAhassomeadvantages:(1)itisstabletocellularnucleasesandproteases,(2 )ithybridizeswithcomplementaryDNAorRNA (cDNA/RNA)sequenceswithhighaffinity ,(3)ithaslownon specificinteractionwithcellularcontentsand (4 )itiseasilysynthesizedbyadoptionofsolidphasepeptidesynthesischemistry .However,thema jorlimitationo…     

Synthesis of New Chrial Building Blocks for Novel Peptide Nucleic Acids

N-Boc protected amino acids of analogues of peptide nucleic acid (PNA),which are a class of conformationally constrained building blocks based on 4-aminoproline backbone with chirality at 2-c and 4-c,have been synthesized.Those monomers can be used for the construction of novel peptide nucleic acid analogues.     

Neural Network Learning of the Interaction Between Peptide Segments of Proteins

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