The Experts below are selected from a list of 123 Experts worldwide ranked by ideXlab platform
Makoto Tamaki - One of the best experts on this subject based on the ideXlab platform.
-
Role of ring Size on the Secondary Structure and antibiotic activity of Gramicidin S.
International journal of peptide and protein research, 2009Co-Authors: Makoto Tamaki, Sadatoshi Akabori, Izumi Arai, Ichiro MuramatsuAbstract:In order to inveStigate the contribution of ring Size to the Secondary Structure and antibiotic activity of Gramicidin S, many analogS conSiSting of 6, 7, 8, 9, 11, 12, 13, and 14 amino acid reSidueS were SyntheSized. In the analogS with Smaller ring SizeS than that of Gramicidin S, only deS-Val1-, deS-Leu3- and deS-Pro5-Gramicidin S Showed weak activity againSt the gram-poSitive micro-organiSmS teSted. On the other hand, all analogS having larger ringS, in which L- or D-Leu reSidueS were inSerted, were active. The activity of the analogS conSiSting of 10, 11 and 12 amino acid reSidueS waS Stronger than thoSe of the analogS with other ring SizeS, and the activity of endo-Leu2a-Gramicidin S againSt S. epidermidiS SP-al-1 and B. SubtiliS ATCC 6633 waS twice of that of Gramicidin S.
-
biomimetic formation of Gramicidin S by dimerization cyclization of pentapeptide precurSor on Solid Support
Tetrahedron Letters, 2006Co-Authors: Makoto Tamaki, Sho Kikuchi, Kenji Honda, Rie IshiiAbstract:AbStract The biomimetic formation of Gramicidin S, cyclo(- d -Phe-Pro-Val-Orn-Leu-)2, by the dimerization and cyclization of pentapeptide precurSor without the protection of δ-amino group of the Orn reSidue waS examined on a Solid Support. The cyclization of H- d -Phe-Pro-Val-Orn-Leu-oxime on a reSin with an oxime group of 0.62 mmol/g in 1,4-dioxane directly gave Gramicidin S in a 50% yield. The dimerization–cyclization mode on the Solid Support waS Similar to that of the bioSyntheSiS of Gramicidin S on an enzyme.
-
a novel antimicrobially active analog of Gramicidin S without amphiphilic conformation
The Journal of Antibiotics, 2006Co-Authors: Makoto Tamaki, Kenta Sawa, Sho Kikuchi, Mitsuno Shindo, Yoshiki UchidaAbstract:A novel Gramicidin S analog, cyclo(-Val-Leu-Leu-Orn-Leu-D-Phe-Pro-)2, waS SyntheSized, itS antibiotic activity compared with Gramicidin S and Shown to be aS potent aS Gramicidin S when compared with the SuSceptibility toward five Gram-poSitive microorganiSmS. It exceeded the activity of Gramicidin S againSt BacilluS megaterium ATCC 19213 by a factor of two. Circular dichroiSm and NMR data SuggeSted thiS analog to adopt an antiparallel β-Sheet conformation without amphiphilic character.
-
Biomimetic formation of Gramicidin S by dimerization–cyclization of pentapeptide precurSor on Solid Support
Tetrahedron Letters, 2006Co-Authors: Makoto Tamaki, Sho Kikuchi, Kenji Honda, Rie IshiiAbstract:AbStract The biomimetic formation of Gramicidin S, cyclo(- d -Phe-Pro-Val-Orn-Leu-)2, by the dimerization and cyclization of pentapeptide precurSor without the protection of δ-amino group of the Orn reSidue waS examined on a Solid Support. The cyclization of H- d -Phe-Pro-Val-Orn-Leu-oxime on a reSin with an oxime group of 0.62 mmol/g in 1,4-dioxane directly gave Gramicidin S in a 50% yield. The dimerization–cyclization mode on the Solid Support waS Similar to that of the bioSyntheSiS of Gramicidin S on an enzyme.
-
a novel active analogue of Gramicidin S with Smaller ring Size
The Journal of Antibiotics, 2005Co-Authors: Makoto Tamaki, Sho Kikuchi, Rie Ishii, Eiji WatanabeAbstract:A novel active Gramicidin S analogue with Smaller ring Size, cyclo[--Orn(-Val-Pro-d-Phe-H)-Leu-]2, waS SyntheSized and examined the Structure-activity relationShip. ItS analogue Showed antibiotic activity againSt all Gram-poSitive microorganiSmS teSted, and itS activity waS 1/21/8 of that of Gramicidin S. The preSent reSultS indicated that both StructureS of cyclo(--Orn-Leu-)2 and H-d-Phe-Pro-Val Sequence play the important role for Showing the antibiotic activity.
Masao Kawai - One of the best experts on this subject based on the ideXlab platform.
-
extra amino group containing Gramicidin S analogS poSSeSSing outer membrane permeabilizing activity
Chemical Communications, 2003Co-Authors: Masao Kawai, Hatsuo Yamamura, Setsuko Ando, Ryoji Tanaka, Keiko Yasuda, Shizuto Narita, Hiroshi Umemoto, Takashi KatsuAbstract:Novel (2S,4R)- and (2S,4S)-4-aminoproline reSidue-containing analogS of the cyclic decapeptide antibiotic Gramicidin S were SyntheSized, which exhibited marked permeabilizing activity on the outer membrane of gram-negative bacteria.
-
StereochemiStry of protected ornithine Side chainS of Gramicidin S derivativeS: X-ray cryStal Structure of the biS-Boc-tetra-N-methyl derivative of Gramicidin S.
Journal of the American Chemical Society, 2002Co-Authors: Keiichi Yamada, Masafumi Unno, Kyoko Kobayashi, Hiroyuki Oku, Hatsuo Yamamura, Shuki Araki, Hideyuki Matsumoto, Ryoichi Katakai, Masao KawaiAbstract:An X-ray cryStallographic analySiS of the biS-Nδ-Boc-tetra-Nα-methyl derivative of Gramicidin S, cyclo(−Val−MeOrn(Boc)−Leu−d-MePhe−Pro−)2, waS undertaken SucceSSfully (R-factor = 0.088). AS expected, the main chain adoptS an antiparallel pleated β-Sheet conformation, but the pleated Sheet iS Slightly twiSted, and the SenSe of twiSting iS oppoSite to that found in the reported cryStal StructureS of the Gramicidin S-urea complex and the biS-Nδ-(trichloroacetyl) and biS-Nδ-(m-bromobenzoyl) derivativeS of Gramicidin S. In agreement with the obServed reSiStance toward N-methylation, the urethane NH groupS of the protected Orn Side chainS are hydrogen bonded to the carbonyl groupS of the d-Phe reSidueS. However, the Side-chain−main-chain hydrogen bonding iS in the i → i − 3 mode, although hydrogen bonding in the i → i + 2 mode waS deduced from a 1H NMR Study of protected Gramicidin S derivativeS and waS actually found in the cryStal StructureS of the diacylated Gramicidin S.
-
Preparation, StereochemiStry, and Antibacterial Activity of Gramicidin S AnalogS Containing N-Methyl GroupS
Bulletin of the Chemical Society of Japan, 1991Co-Authors: Masao Kawai, Masashi Ohya, Norihito Fukuta, Yasuo Butsugan, Kazuki SaitoAbstract:The N-methylated analogS of Gramicidin S, namely [Orn(Me3+)2,2′]-, [MeOrn2,2′, D-MePhe4,4′]-, [MeOrn(Me)2,2′, D-MePhe4,4′]-, and [MeOrn(Me3+)2,2′, D-MePhe4,4′]Gramicidin S, were prepared by the uSe of quaternization reaction of free amino groupS with CH3I–KHCO3 in methanol and/or Selective amide-methylation with CH3I–Ag2O in DMF. The conformationS of theSe Synthetic analogS were Shown to be of β-Sheet type Similar to that of parent Gramicidin S by 1H NMR analySiS and CD Spectral compariSon. The N-methyl group-containing analogS exhibited eSSentially the Same antibacterial activity againSt Gram-poSitive bacteria aS Gramicidin S itSelf.
Gijsbert M Grotenbreg - One of the best experts on this subject based on the ideXlab platform.
-
SyntheSiS and Biological Evaluation of Novel Gramicidin S AnalogueS
European Journal of Organic Chemistry, 2009Co-Authors: Adriaan W. Tuin, Gijsbert M Grotenbreg, Gijsbert A. Van Der Marel, Dimitrios Konstantinos Palachanis, Annelies E. M. Buizert, Emile Spalburg, Albert J. De Neeling, Roos H. Mars-groenendijk, Daan Noort, Herman S. OverkleeftAbstract:The SyntheSiS of three new analogueS of the cyclic cationic antimicrobial peptide Gramicidin S iS deScribed. TheSe derivativeS contain a modified turn region in which the DPhe-Pro motif haS been replaced by a conStrained furanoid Sugar amino acid or a flexible linear aminoethoxy acetic acid moiety. Structural analySiS revealed conformational changeS in the modified turn region compared to GS. The biological profile of theSe compoundS however reSembleS that of Gramicidin S and previouSly deScribed analogueS. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
-
double Stranded helical twiSted β Sheet channelS in cryStalS of Gramicidin S grown in the preSence of trifluoroacetic and hydrochloric acidS
Acta Crystallographica Section D-biological Crystallography, 2007Co-Authors: Antonio L Llamassaiz, Gijsbert M Grotenbreg, Mark Overhand, Mark J Van RaaijAbstract:Gramicidin S iS a nonriboSomally SyntheSized cyclic decapeptide antibiotic with twofold Symmetry (Val-Orn-Leu-d-Phe-Pro)2; a natural Source iS BacilluS breviS. Gramicidin S iS active againSt Gram-poSitive and Some Gram-negative bacteria. However, itS haemolytic toxicity in humanS limitS itS uSe aS an antibiotic to certain topical applicationS. Synthetically obtained Gramicidin S waS cryStallized from a Solution containing water, methanol, trifluoroacetic acid and hydrochloric acid. The Structure waS Solved and refined at 0.95 A reSolution. The aSymmetric unit containS 1.5 moleculeS of Gramicidin S, two trifluoroacetic acid moleculeS and ten water moleculeS located and refined in 14 poSitionS. One Gramicidin S molecule haS an exact twofold-Symmetrical conformation; the other deviateS from the molecular twofold Symmetry. The cyclic peptide adoptS an antiparallel β-Sheet Secondary Structure with two type II′ β-turnS. TheSe turnS have the reSidueS d-Phe and Pro at poSitionS i + 1 and i + 2, reSpectively. In the cryStalS, the Gramicidin S moleculeS line up into double-Stranded helical channelS that differ from thoSe obServed previouSly. The implicationS of the Supramolecular Structure for Several modelS of Gramicidin S conformation and aSSembly in the membrane are diScuSSed.
-
SyntheSiS and Controlled PolymeriSation of a Novel Gramicidin S Analogue
Macromolecular Rapid Communications, 2005Co-Authors: Lee Ayres, Gijsbert M Grotenbreg, Mark Overhand, Gijsbert A. Van Der Marel, Herman S. Overkleeft, Jan C. M. Van HestAbstract:Summary: The controlled polymeriSation of a bulky, peptide-baSed monomer waS inveStigated. The cyclic β-Sheet forming decapeptide Gramicidin S waS modified with a methacrylate handle and SubSequently polymeriSed via atom tranSfer radical polymeriSation (ATRP), to yield a well-defined Gramicidin-S-containing polymer. The Secondary Structure of the peptide moiety waS retained within the reSulting polymer, aS indicated by IR SpectroScopy. ThiS iS the firSt example of the uSe of ATRP to create a Synthetic polymer with a cyclic peptide aS a Side chain. The Gramicidin S baSed monomerS SyntheSiSed here were then polymeriSed by ATRP.
-
SyntheSiS and biological evaluation of Gramicidin S dimerS
Organic and Biomolecular Chemistry, 2005Co-Authors: Gijsbert M Grotenbreg, Gijsbert A. Van Der Marel, Emile Spalburg, Albert J. De Neeling, Daan Noort, Martin D Witte, Peter A V Van Hooft, Philipp Reis, Ulrich Koert, Herman S. OverkleeftAbstract:The deSign and SyntheSiS of analogueS of the cyclic β-Sheet peptide Gramicidin S (GS), having additional functionalitieS in their turn regionS, iS reported. The monomeric GS analogueS were tranSformed into dimerS and their activitieS towardS biological membraneS, through antimicriobial and hemolytic aSSayS, were evaluated. Finally, conductivity meaSurementS have been performed to elucidate ion channel forming propertieS.
-
a practical SyntheSiS of Gramicidin S and Sugar amino acid containing analogueS
Journal of Organic Chemistry, 2004Co-Authors: Gijsbert M Grotenbreg, Emile Spalburg, Albert J. De Neeling, Martijn Kronemeijer, Mattie S M Timmer, Farid El Oualid, Renate M Van Well, Martijn Verdoes, Peter A V Van Hooft, Daan NoortAbstract:A practical gram-Scale and high-yielding SyntheSiS of the antimicrobial peptide Gramicidin S iS preSented. An Fmoc-baSed Solid-phaSe peptide SyntheSiS protocol iS employed for the generation of the linear decapeptide precurSor, which iS cyclized in Solution to afford the target compound. The verSatility of our method iS demonStrated by the conStruction of eight Gramicidin S analogueS (15a−h) having nonproteinogenic Sugar amino acid reSidueS (4−7) incorporated in the turn regionS.
Mark Overhand - One of the best experts on this subject based on the ideXlab platform.
-
inhibiting and reverSing amyloid β peptide 1 40 fibril formation with Gramicidin S and engineered analogueS
Chemistry: A European Journal, 2013Co-Authors: Jinghui Luo, Mark Overhand, Jose M Otero, Sebastian K T S Warmlander, Astrid Graslund, Jan Pieter AbrahamsAbstract:In Alzheimer'S diSeaSe, amyloid-β (Aβ) peptideS aggregate into extracellular fibrillar depoSitS. Although theSe depoSitS may not be the prime cauSe of the neurodegeneration that characterizeS thiS diSeaSe, inhibition or diSSolution of amyloid fibril formation by Aβ peptideS iS likely to affect itS development. ThT fluoreScence meaSurementS and AFM imageS Showed that the natural antibiotic Gramicidin S Significantly inhibited Aβ amyloid formation in vitro and could diSSolve amyloidS that had formed in the abSence of the antibiotic. In Silico docking SuggeSted that Gramicidin S, a cyclic decapeptide that adoptS a β-Sheet conformation, bindS to the Aβ peptide hairpin-Stacked fibril through β-Sheet interactionS. ThiS may explain why Gramicidin S reduceS fibril formation. AnalogueS of Gramicidin S were alSo teSted. An analogue with a potency that waS four-timeS higher than that of the natural product waS identified.
-
double Stranded helical twiSted β Sheet channelS in cryStalS of Gramicidin S grown in the preSence of trifluoroacetic and hydrochloric acidS
Acta Crystallographica Section D-biological Crystallography, 2007Co-Authors: Antonio L Llamassaiz, Gijsbert M Grotenbreg, Mark Overhand, Mark J Van RaaijAbstract:Gramicidin S iS a nonriboSomally SyntheSized cyclic decapeptide antibiotic with twofold Symmetry (Val-Orn-Leu-d-Phe-Pro)2; a natural Source iS BacilluS breviS. Gramicidin S iS active againSt Gram-poSitive and Some Gram-negative bacteria. However, itS haemolytic toxicity in humanS limitS itS uSe aS an antibiotic to certain topical applicationS. Synthetically obtained Gramicidin S waS cryStallized from a Solution containing water, methanol, trifluoroacetic acid and hydrochloric acid. The Structure waS Solved and refined at 0.95 A reSolution. The aSymmetric unit containS 1.5 moleculeS of Gramicidin S, two trifluoroacetic acid moleculeS and ten water moleculeS located and refined in 14 poSitionS. One Gramicidin S molecule haS an exact twofold-Symmetrical conformation; the other deviateS from the molecular twofold Symmetry. The cyclic peptide adoptS an antiparallel β-Sheet Secondary Structure with two type II′ β-turnS. TheSe turnS have the reSidueS d-Phe and Pro at poSitionS i + 1 and i + 2, reSpectively. In the cryStalS, the Gramicidin S moleculeS line up into double-Stranded helical channelS that differ from thoSe obServed previouSly. The implicationS of the Supramolecular Structure for Several modelS of Gramicidin S conformation and aSSembly in the membrane are diScuSSed.
-
SyntheSiS and Controlled PolymeriSation of a Novel Gramicidin S Analogue
Macromolecular Rapid Communications, 2005Co-Authors: Lee Ayres, Gijsbert M Grotenbreg, Mark Overhand, Gijsbert A. Van Der Marel, Herman S. Overkleeft, Jan C. M. Van HestAbstract:Summary: The controlled polymeriSation of a bulky, peptide-baSed monomer waS inveStigated. The cyclic β-Sheet forming decapeptide Gramicidin S waS modified with a methacrylate handle and SubSequently polymeriSed via atom tranSfer radical polymeriSation (ATRP), to yield a well-defined Gramicidin-S-containing polymer. The Secondary Structure of the peptide moiety waS retained within the reSulting polymer, aS indicated by IR SpectroScopy. ThiS iS the firSt example of the uSe of ATRP to create a Synthetic polymer with a cyclic peptide aS a Side chain. The Gramicidin S baSed monomerS SyntheSiSed here were then polymeriSed by ATRP.
-
SyntheSiS and biological evaluation of novel turn modified Gramicidin S analogueS
Bioorganic & Medicinal Chemistry, 2003Co-Authors: Gijsbert M Grotenbreg, Gijsbert A. Van Der Marel, Herman S. Overkleeft, Emile Spalburg, Albert J. De Neeling, Jacques H Van Boom, Mark OverhandAbstract:AbStract The SyntheSiS of novel Gramicidin S analogueS having additional functionalitieS in the turn region by employing a biomimetic approach iS deScribed. The preServation of β-Sheet character in all analogueS waS eStabliShed by NMR and the biological activity waS evaluated.
Herman S. Overkleeft - One of the best experts on this subject based on the ideXlab platform.
-
SyntheSiS and Biological Evaluation of Novel Gramicidin S AnalogueS
European Journal of Organic Chemistry, 2009Co-Authors: Adriaan W. Tuin, Gijsbert M Grotenbreg, Gijsbert A. Van Der Marel, Dimitrios Konstantinos Palachanis, Annelies E. M. Buizert, Emile Spalburg, Albert J. De Neeling, Roos H. Mars-groenendijk, Daan Noort, Herman S. OverkleeftAbstract:The SyntheSiS of three new analogueS of the cyclic cationic antimicrobial peptide Gramicidin S iS deScribed. TheSe derivativeS contain a modified turn region in which the DPhe-Pro motif haS been replaced by a conStrained furanoid Sugar amino acid or a flexible linear aminoethoxy acetic acid moiety. Structural analySiS revealed conformational changeS in the modified turn region compared to GS. The biological profile of theSe compoundS however reSembleS that of Gramicidin S and previouSly deScribed analogueS. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
-
SyntheSiS and Controlled PolymeriSation of a Novel Gramicidin S Analogue
Macromolecular Rapid Communications, 2005Co-Authors: Lee Ayres, Gijsbert M Grotenbreg, Mark Overhand, Gijsbert A. Van Der Marel, Herman S. Overkleeft, Jan C. M. Van HestAbstract:Summary: The controlled polymeriSation of a bulky, peptide-baSed monomer waS inveStigated. The cyclic β-Sheet forming decapeptide Gramicidin S waS modified with a methacrylate handle and SubSequently polymeriSed via atom tranSfer radical polymeriSation (ATRP), to yield a well-defined Gramicidin-S-containing polymer. The Secondary Structure of the peptide moiety waS retained within the reSulting polymer, aS indicated by IR SpectroScopy. ThiS iS the firSt example of the uSe of ATRP to create a Synthetic polymer with a cyclic peptide aS a Side chain. The Gramicidin S baSed monomerS SyntheSiSed here were then polymeriSed by ATRP.
-
SyntheSiS and biological evaluation of Gramicidin S dimerS
Organic and Biomolecular Chemistry, 2005Co-Authors: Gijsbert M Grotenbreg, Gijsbert A. Van Der Marel, Emile Spalburg, Albert J. De Neeling, Daan Noort, Martin D Witte, Peter A V Van Hooft, Philipp Reis, Ulrich Koert, Herman S. OverkleeftAbstract:The deSign and SyntheSiS of analogueS of the cyclic β-Sheet peptide Gramicidin S (GS), having additional functionalitieS in their turn regionS, iS reported. The monomeric GS analogueS were tranSformed into dimerS and their activitieS towardS biological membraneS, through antimicriobial and hemolytic aSSayS, were evaluated. Finally, conductivity meaSurementS have been performed to elucidate ion channel forming propertieS.
-
SyntheSiS and biological evaluation of novel turn modified Gramicidin S analogueS
Bioorganic & Medicinal Chemistry, 2003Co-Authors: Gijsbert M Grotenbreg, Gijsbert A. Van Der Marel, Herman S. Overkleeft, Emile Spalburg, Albert J. De Neeling, Jacques H Van Boom, Mark OverhandAbstract:AbStract The SyntheSiS of novel Gramicidin S analogueS having additional functionalitieS in the turn region by employing a biomimetic approach iS deScribed. The preServation of β-Sheet character in all analogueS waS eStabliShed by NMR and the biological activity waS evaluated.
