			Home About us Contact

Aminoisobutyric Acid (aminoisobutyric + acid)

Distribution by Scientific Domains

Chemistry	75%

Selected Abstracts

Amyloid-Like Fibrillogenesis through Supramolecular Helix-Mediated Self-Assembly of Tetrapeptides Containing Non-Coded , -Aminoisobutyric Acid (Aib) and 3-Aminobenzoic Acid (m -ABA)

HELVETICA CHIMICA ACTA, Issue 6 2010
Arpita Dutta
Abstract Single-crystal X-ray diffraction studies of two terminally protected tetrapeptides Boc-Ile-Aib-Val- m -ABA-OMe (I) and Boc-Ile-Aib-Phe- m -ABA-OMe (II) (Aib=, -aminoisobutyric acid; m -ABA=meta -aminobenzoic acid) reveal that they form continuous H-bonded helices through the association of double-bend (type III and I) building blocks. NMR Studies support the existence of the double-bend (type III and I) structures of the peptides in solution also. Field emission scanning electron-microscopic (FE-SEM) and high-resolution transmission electron-microscopic (HR-TEM) images of the peptides exhibit amyloid-like fibrils in the solid state. The Congo red-stained fibrils of peptide I and II, observed between crossed polarizers, show green-gold birefringence, a characteristic of amyloid fibrils. [source]

Effects of ,-aminoisobutyric acid on leptin production and lipid homeostasis: mechanisms and possible relevance for the prevention of obesity

FUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 3 2010
Karima Begriche
Abstract ,-Aminoisobutyric acid (BAIBA) is a catabolite of thymine and antiretroviral thymine analogues AZT and d4T. We recently discovered that this ,-amino acid is able to enhance fatty acid oxidation and reduce body weight in mice through an increased production of leptin by the white adipose tissue (WAT). Furthermore, BAIBA could have favourable effects on nonalcoholic steatohepatitis in a leptin-independent manner. In the present review, we shall recall the circumstances that led us to discover the effects of BAIBA on body fat mass and lipid homeostasis. In addition, we put forward several hypothetical mechanisms whereby BAIBA could enhance leptin secretion by WAT and present some anti-inflammatory effects in the liver. We also discuss in this review (i) the deleterious impacts caused by the absence of, or low leptin expression on lipid homeostasis and body weight in humans and animals and (ii) recent data from other investigators suggesting that increasing leptin levels and/or responsiveness may be indeed an attractive pharmacological strategy in order to prevent (and/or treat) obesity, at least in some individuals. [source]

Metal ion-binding ability of tetrapeptides containing ,-aminoisobutyric acid

JOURNAL OF PEPTIDE SCIENCE, Issue 3 2004
Masayuki Hanyu
Abstract ,-Aminoisobutyric acid (Aib), one of the C,, , -disubstituted glycines, is a sterically hindered amino acid that acts as a conformational constraint in peptides. However, studies for the application of the ability of Aib to control conformation are quite few. The paper focuses on the molecular recognition ability of acyclic oligopeptides containing Aib. Liquid,liquid extraction of nine kinds of metal ions from aqueous layers to nonpolar organic layers with acyclic tetrapeptides, X-Trp-Xaa2 -Gly-Xaa4 -NH-Ar (X = H or C6H5CH2OCO (Z), Xaa2 = Aib or Gly, Xaa4 = Leu or Ala, Ar = phenyl or 3,5-dimethylphenyl) was examined using picrate as the anion of ion pairs. The extraction behaviour of the metal ions with the tetrapeptides was investigated in the pH range from 3 to 9. In the case of basic pH regions, Cu(II) and Ag(I) were effectively extracted with Trp-Aib-Gly-Leu-NH-Ar. Pd(II) was specifically extracted with Trp-Aib-Gly-Leu-NH-Ar in acidic pH regions. The extraction percent (%E) of the peptide host, which has a 3,5-dimethylphenyl group, was even larger than that of the host, which has a phenyl group. Moreover, Pd(II) was extracted with a peptide host which has Leu and a 3,5-dimethylphenyl group in the absence of picrate as the anion of ion pairs. The free ,-amino group, the turn conformation and the hydrophobicity of peptide molecules were important factors for the extraction of the metals. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd. [source]

Epidermal Growth Factor Regulates Amino Acid Transport in Chick Embryo Hepatocytes via Protein Kinase C

EXPERIMENTAL PHYSIOLOGY, Issue 4 2000
Maria Marino
System A-mediated amino acid transport, activation of different steps of signal transduction and involvement of different isoforms of protein kinase C (PKC) have been investigated in chick embryo hepatocytes after epidermal growth factor (EGF) stimulation. EGF rapidly (10 min) increased the rate of aminoisobutyric acid (AIB) uptake in chick embryo hepatocytes freshly isolated on the 19th day of embryonic life, while no change was detectable at other embryonal stages. The growth factor stimulation was abolished by PKC and tyrosine kinase inhibitors and was mimicked by 4-phorbol-12-myristate-13-acetate, dimethyl-2 (PMA). EGF treatment did not modify the phosphorylation of the , isoform of phospholipase C (PLC-,), and inositol trisphosphate (IP3) and intracellular calcium levels, but it induced an increase in PKC activity. Our data show that EGF regulates amino acid uptake, via PKC and without PLC-, activation, only in the last period of chick embryo hepatocyte development. The effects of growth factor on PKC activity suggest the involvement of PKC-, and -, isoforms in EGF modulation of amino acid transport. [source]

Effects of ,-aminoisobutyric acid on leptin production and lipid homeostasis: mechanisms and possible relevance for the prevention of obesity

Amyloid-Like Fibrillogenesis through Supramolecular Helix-Mediated Self-Assembly of Tetrapeptides Containing Non-Coded , -Aminoisobutyric Acid (Aib) and 3-Aminobenzoic Acid (m -ABA)

Synthesis and Conformational Analysis of Pentapeptides Containing Enantiomerically Pure 2,2-Disubstituted Glycines

HELVETICA CHIMICA ACTA, Issue 3 2008
Kathrin
Abstract The synthesis and conformational analysis of model pentapeptides with the sequence Z-Leu-Aib-Xaa-Gln-Valol is described. These peptides contain two 2,2-disubstituted glycines (,,, -disubstituted , -amino acids), i.e., Aib (aminoisobutyric acid), and a series of unsymmetrically substituted, enantiomerically pure amino acids Xaa. These disubstituted amino acids were incorporated into the model peptides via the ,azirine/oxazolone method'. Conformational analysis was performed in solution by means of NMR techniques and, in the solid state, by X-ray crystallography. Both methods show that the backbones of these model peptides adopt helical conformations, as expected for 2,2-disubstitued glycine-containing peptides. [source]

The ,Azirine/Oxazolone Method' on Solid Phase: Introduction of Various ,,, -Disubstituted , -Amino Acids

HELVETICA CHIMICA ACTA, Issue 1 2006
Simon Stamm
Abstract Peptides containing various ,,, -disubstituted , -amino acids, such as , -aminoisobutyric acid (Aib), 1-aminocyclopentane-1-carboxylic acid, , -methylphenylalanine, and 3-amino-3,4,5,6-tetrahydro-2H -pyran-3-carboxylic acid have been synthesized from the N- to the C-terminus by the ,azirine/oxazolone method' under solid-phase conditions. In this convenient method for the synthesis of sterically demanding peptides on solid-phase, 2H -azirin-3-amines are used to introduce the ,,, -disubstituted , -amino acids without the need for additional reagents. Furthermore, the synthesis of poly(Aib) sequences has been explored. [source]

Sequence diversity of the peptaibol antibiotic suzukacillin-A from the mold Trichoderma viride

JOURNAL OF PEPTIDE SCIENCE, Issue 5 2006
Corina Krause
Abstract From the culture broth of the mold Trichoderma viride, strain 63 C-I, the polypeptide antibiotic suzukacillin (SZ) was isolated. A peptide mixture named SZ-A was obtained by crystallization from crude SZ. Individual peptides from SZ-A were isolated by semipreparative HPLC and sequences were determined by HPLC-ESI-MS. The data confirm a general sequence of SZ-A published previously and in addition establish the individual sequences of 15 acetylated eicosa peptides with C -terminal alcohols. The major peptide SZ-A4 (21% of all peptides) shows the sequence: Ac-Aib-Ala-Aib-Ala-Aib-Ala6 -Gln-Aib-Lx9 -Aib-Gly-Aib12 -Aib-Pro-Vx15 -Aib-Vx17 -Gln-Gln-Fol. Amino acid exchanges of the peptaibol are located in position 6 (Ala/Aib), 9 (Vx/Lx), 12 (Aib/Lx), 17 (Aib/Vx) and possibly at position15 (Val/Iva) (uncommon abbreviations: Aib (,-aminoisobutyric acid); Iva (D -isovaline); Lx (L -leucine or L -isoleucine); Vx (L -valine or D -isovaline); Fol (L -phenylalaninol)). Copyright © 2005 European Peptide Society and John Wiley & Sons, Ltd. [source]

Metal ion-binding ability of tetrapeptides containing ,-aminoisobutyric acid

Polycyclic aromatic hydrocarbons and amino acids in meteorites and ice samples from LaPaz Icefield, Antarctica

METEORITICS & PLANETARY SCIENCE, Issue 9 2008
Oliver BOTTA
Four LL5 ordinary chondrites (OCs) and one CK carbonaceous chondrite were collected as part of the 2003/2004 ANSMET season. Ice samples collected from directly underneath the meteorites were extracted. In addition, exhaust particles from the snowmobiles used during the expedition were collected to investigate possible contributions from this source. The meteorite samples, the particulate matter and solid-state extracts of the ice samples and the exhaust filters were subjected to two-step laser mass spectrometry (L2MS) to investigate the PAH composition. For amino acids analysis, the meteorites were extracted with water and acid hydrolyzed, and the extracts were analyzed with offline OPA/NAC derivatization combined with liquid chromatography with UV fluorescence detection and time of flight mass spectrometry (LC-FD/ToF-MS). PAHs in the particulate matter of the ice were found to be qualitatively similar to the meteorite samples, indicating that micron-sized grains of the meteorite may be embedded in the ice samples. The concentration levels of dissolved PAHs in all the ice samples were found to be below the detection limit of the L2MS. The PAH composition of the snowmobile exhaust is significantly different to the one in particulate matter, making it an unlikely source of contamination for Antarctic meteorites. The amino acids glycine, ,-alanine and ,-amino- n -butyric acid that were detected at concentrations of 3 to 19 parts per billion (ppb) are probably indigenous to the Antarctic meteorites. Some of the LaPaz ice samples were also found to contain amino acids at concentration levels of 1 to 33 parts per trillion (ppt), in particular ,-aminoisobutyric acid (AIB), an abundant non-protein amino acid of extraterrestrial origin found in some carbonaceous chondrites. We hypothesize that this amino acid could have been extracted from Antarctic micrometeorites and the particulate matter of the meteorites during the concentration procedure of the ice samples. [source]

Chiral interaction in Gly-capped N-terminal motif of 310 -helix and domino-type induction in helix sense

BIOPOLYMERS, Issue 4 2006
Naoki Ousaka
Abstract Chiral interaction of helical peptide with chiral molecule, and concomitant induction in its helix sense have been demonstrated in optically inactive nonapeptide (1) possessing Gly at its N-terminus: H,Gly,(,ZPhe,Aib)4,OCH3 (1: ,ZPhe = Z-dehydrophenylalanine; Aib = ,-aminoisobutyric acid). Spectroscopic measurements [mainly nuclear magnetic resonance (NMR) and circular diochroism (CD)] as well as theoretical simulation have been carried out for that purpose. Peptide 1 in the 310 -helix tends to adopt preferentially a right-handed screw sense by chiral Boc- L -amino acid (Boc: t -butoxycarbonyl). Induction in the helix sense through the noncovalent chiral domino effect should be derived primarily from the complex supported by the three-point coordination on the N-terminal sequence. Thus the 310 -helical terminus consisting of only ,-amino acid residues enables chiral recognition of the Boc-amino acid molecule, leading to modulation of the original chain asymmetry. Dynamics in the helix-sense induction also have been discussed on the basis of a low-temperature NMR study. Furthermore, the inversion of induced helix sense has been achieved through solvent effects. © 2006 Wiley Periodicals, Inc. Biopolymers 83:337,351, 2006 This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source]

Crystal structure of achiral nonapeptide Boc,(Aib,,zPhe)4,Aib,OMe at atomic resolution: Evidence for a 310 -helix

BIOPOLYMERS, Issue 3 2003
Yoshihito Inai
Abstract An x-ray crystallographic analysis was carried out for Boc,(Aib,,ZPhe)4,Aib,OMe (1: Boc = t -butoxycarbonyl; Aib = ,-aminoisobutyric acid; ,ZPhe = Z -,,,-didehydrophenylalanine) to provide the precise conformational parameters of the octapeptide segment ,(Aib,,ZPhe)4,. Peptide 1 adopted a typical 310 -helical conformation characterized by ,,, = ±55.8° (50°,65°), ,,, = ±26.7° (15°,45°), and ,,, = ±179.5° (168°,188°) for the average values of the ,(Aib,,ZPhe)4, segment (the range of the eight values). The 310 -helix contains 3.1 residues per turn, being close to the "perfect 310 -helix" characterized by 3.0 residues per turn. NMR and Fourier transform infrared (FTIR) spectroscopy revealed that the 310 -helical conformation at the atomic resolution is essentially maintained in solution. Energy minimization of peptide 1 by semiempirical molecular orbital calculation converged to a 310 -helical conformation similar to the x-ray crystallographic 310 -helix. The preference for a 310 -helix in the ,(Aib,,ZPhe)4, segment is ascribed to strong inducers of the 310 -helix inherent in Aib and ,ZPhe residues,in particular, the Aib residues tend to stabilize a 310 -helix more effectively. Therefore, the ,(Aib,,ZPhe)4, segment is useful to rationally design an optically inactive 310 -helical backbone, which will be of great importance to provide novel insights into noncovalent and covalent chiral interactions of a helical peptide with a chiral molecule. © 2003 Wiley Periodicals, Inc. Biopolymers 70: 310,322, 2003 [source]

Preferred Conformations of Peptides Containing tert -Leucine, a Sterically Demanding, Lipophilic ,-Amino Acid with a Quaternary Side-Chain C, Atom

CHEMISTRY - A EUROPEAN JOURNAL, Issue 8 2005
Fernando Formaggio Prof.
Abstract Terminally protected homopeptides of tert -leucine, from the dimer to the hexamer, co-oligopeptides of tert -leucine in combination with ,-aminoisobutyric acid or glycine residues up to the hexamer level, and simple dipeptides representing known scaffolds for catalysts in asymmetric organic reactions were prepared by solution methods and fully characterized. The results of conformation analysis, performed by use of FT-IR absorption, NMR, CD, and X-ray diffraction techniques, indicate that this hydrophobic ,-amino acid with tetrasubstitution at the C, atom is structurally versatile. We show that it prefers extended or semiextended conformations, but can also be accommodated in folded structures, provided that these are biased by the presence of helicogenic residues. The current large-scale production of Tle, combined with its conformational preferences unravelled in this work, should make this bulky, hydrophobic, C, -trisubstituted ,-amino acid a regular building block of any strategy seeking to tailor peptides with improved catalytic and pharmacological properties. [source]

The Interaction of Highly Helical Structural Mutants with the NOP Receptor Discloses the Role of the Address Domain of Nociceptin/Orphanin FQ

CHEMISTRY - A EUROPEAN JOURNAL, Issue 7 2005
Teodorico Tancredi Dr.
Abstract Nociceptin is a heptadecapeptide whose sequence is similar to that of Dynorphin A, sharing a message domain characterized by two glycines and two aromatic residues, and a highly basic C-terminal address domain but, in spite of these similarities, displays no opioid activity. Establishing the relative importance of the message and address domains of nociceptin has so far been hampered by its extreme conformational flexibility. Here we show that mutants of this peptide, designed to increase the helical content in the address domain, can be employed to explain the mode of interaction with the NOP receptor. Nociceptin analogues in which Ala residues are substituted with aminoisobutyric acid (Aib) show a substantial increment of activity in their interaction with the NOP receptor. The increment of biological activity was attributed to the well-documented ability of Aib to induce helicity. Here we have verified this working hypothesis by a conformational investigation extended to new analogues in which the role of Aib is taken up by Leu. The NMR conformational analysis confirms that all Ala/Aib peptides as well as [Leu7,11]-N/OFQ-amide and [Leu11,15]-N/OFQ-amide mutants (N/OFQ=nociceptin/orphanin FQ) have comparable helix content in helix-promoting media. We show that the helical address domain of nociceptin can place key basic residues at an optimal distance from complementary acidic groups of the EL2 loop of the receptor. Our structural data are used to rationalize pharmacological data which show that although [Leu11,15]-N/OFQ-amide has an activity comparable to those of Ala/Aib peptides, [Leu7,11]-N/OFQ-amide is less active than N/OFQ-amide. We hypothesize that bulky residues cannot be hosted in or near the hinge region (Thr5 -Gly6 -Ala7) without severe steric clash with the receptor. This hypothesis is also consistent with previous data on this hinge region obtained by systematic substitution of Thr, Gly, and Ala with Pro. [source]

Recent Advances and Future Prospects in Peptaibiotics, Hydrophobin, and Mycotoxin Research, and Their Importance for Chemotaxonomy of Trichoderma and Hypocrea

CHEMISTRY & BIODIVERSITY, Issue 5 2008
Thomas Degenkolb
Abstract Fungi of the genus Trichoderma with teleomorphs in Hypocrea are abundant producers of a group of amphiphilic, non-ribosomal peptide antibiotics, which are rich in the non-proteinogenic amino acid Aib (, -aminoisobutyric acid). They are referred to as peptaibiotics, or peptaibols, if a 1,2-amino alcohol is present at the C-terminus. Trichoderma/Hypocrea, like other ascomycetous fungi, also produce hydrophobins, a class of small, cysteine-rich proteins. Advanced soft ionization mass spectrometric techniques such as LC-CID-MS, LC-ESI-MSn, and IC-MALDI-TOF-MS enabled the high-throughput analysis, simultaneous detection and sequence determination of peptaibiotics and hydrophobins from minute quantities of fungal materials. Some Trichoderma species have been recognized to produce peptaibiotics as well as simple mycotoxins of the trichothecene group. The combination of sequence data of both groups of peptides with the pattern of low-molecular-weight secondary metabolites, including trichothecene-type mycotoxins, independently confirmed the results of morphological, molecular, and phylogenetic analyses. This approach established a new lineage in Trichoderma/Hypocrea, the Brevicompactum clade, comprising four new and one redescribed species. Notably, commercial preparations of single or mixed cultures of Trichoderma species, in particular T. harzianum, and T. koningii, are registered as biocontrol agents for soil and plant pathogens. In this context, it is emphasized that the four mycotoxin-producing species of the recently established Brevicompactum clade (T. brevicompactum, T. arundinaceum, T. turrialbense, and T. protrudens) are not closely related to any of the Trichoderma species currently used as biocontrol agents. Furthermore, possible health concerns about release of peptaibiotics in the biosphere are discussed with respect to their bioactivities and their use as drugs in human and veterinary medicine. Finally, future prospects regarding novel bioactivities and further research needs, including interdisciplinary taxonomic approaches, are outlined. [source]