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1.
A series of single isomers tetrahydro‐β‐carboline diketopiperazines were stereoselectively synthesized starting from l ‐tryptophan methyl ester hydrochloride and six aldehydes through a four‐step reaction including Pictet‐Spengler reaction, crystallization‐induced asymmetric transformations (CIAT), Schotten‐Baumann reaction, and intramolecular ester amidation. The chemical structures were characterized by nuclear magnetic resonance (NMR) and elemental analysis, among which two compounds were determined by x‐ray single crystal diffraction. Moreover, antimicrobial activities of all the compounds were also tested. Chirality 25:656–662, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
2.
Marcin Stasiak Mirosław T. Leplawy 《International journal of peptide research and therapeutics》1998,5(5-6):449-453
Summary The solid-phase synthesis of peptides derived from the sterically hindered α-hydroxymethylserine (HmS) was investigated. The
acid-sensitive,O,O-isopropylidene (Ipr) protection of HmS is compatible with the Fmoc chemistry, represented here by the Fmoc-HmS(Ipr)-OH and
Fmoc-HmS(Ipr)-F derivatives. Three analogs of the opioid pentapeptide DADLE with a single or two consecutive HmS residue(s)
were synthesized using Wang resin as the solid support. The HATU method has been shown to effectively accomplish ‘difficult’
couplings with the HmS(Ipr) residue. Wang resin is not suitable, for the synthesis of sequences with a C-terminal HmS because
of the easy formation of the diketopiperazine resulting from the cyclization of the susceptible dipeptide sequence AA-HmS(Ipr)
bound to the resin. A further drawback of the Wang resin methodology is the increased danger of the undersired N→O-acyl shift,
when long-lasting acidic cleavage is applied. These side reactions are totally suppressed when the 2-chlorotrityl polystyrene
is used as a solid support. The mild conditions (AcOH/TFE/DCM) applied for the peptide detachment from this resin do not affect
the Ipr protection, affording highly pure fragments with HmS(Ipr) residues suitable for post-cleavage condensation, cyclization
or controlled side-chain deprotection. This approach is documented by the efficient synthesis of linear and cyclic analogs
of the opioid hexapeptide DTLET containing two residues of HmS or HmS(Ipr) in positions 2 and 6. 相似文献
3.
Michael Beisswenger Taku Yoshiya Yoshiaki Kiso Chiara Cabrele 《Journal of peptide science》2010,16(6):303-308
Synthetic peptides reproducing the helix‐loop‐helix (HLH) domains of the Id proteins fold into highly stable helix bundles upon self‐association. Recently, we have shown that the replacement of the dipeptide Val‐Ser at the loop–helix‐2 junction with the corresponding O‐acyl iso‐dipeptide leads to a completely unfolded state that only refolds after intramolecular O → N acyl migration. Herein, we report on an Id HLH analog based on the substitution of the Pro‐Ser motif at the helix‐1–loop junction with the corresponding O‐acyl iso‐dipeptide. This analog has been successfully synthesized by solid‐phase Fmoc chemistry upon suppression of DKP formation. No secondary structure could be detected for the O‐acyl iso‐peptide before its conversion into the native form by O → N acyl shift. These results show that the loop–helix junctions are determinant for the folded/unfolded state of the Id HLH domain. Further, despite the high risk of DKP formation, peptides containing O‐acyl iso‐Pro‐Ser/Thr units are synthetically accessible by Fmoc chemistry. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
4.
《Bioscience, biotechnology, and biochemistry》2013,77(11):2341-2345
Cyclo(His–Phe) was effectively converted to its dehydro derivatives by the enzyme of Streptomyces albulus KO-23, an albonoursin-producing actinomycete. Two types of dehydro derivatives were isolated from the reaction mixture and identified as cyclo(ΔHis–ΔPhe) and cyclo(His–ΔPhe). This is the first report on cyclo(His–ΔPhe) and the enzymatic preparation of both compounds. Cyclo(ΔHis–ΔPhe), a tetradehydro cyclic dipeptide, exhibited a minimum inhibitory concentration of 0.78 μmol/ml inhibitory activity toward the first cleavage of sea urchin embryos, in contrast to cyclo(His–ΔPhe) that had no activity. The finding that the isoprenylated derivative of cyclo(ΔHis–ΔPhe), dehydrophyenylahistin, had 2,000 times higher activity than cyclo(ΔHis–ΔPhe) indicates that an isoprenyl group attached to an imidazole ring of the compound was essential for the inhibitory activity. 相似文献
5.
Nikolett Mihala Antal Csámpai Janez Ilas Danijel Kikelj Robert Kiss Helga Süli-Vargha 《Journal of peptide science》2006,12(10):663-669
Alternative RGD mimetics-with the exception of glycine-c(Arg-Asp) 1, c(Arg-Glu) 2 and c[Arg-Asp(Phe-OH)] 3 were synthesized. The DKPs were prepared on solid phase with orthogonal protection allowing further derivatization in solution. During solution phase cyclization in NH(3)/methanol, the side chain benzyl ester group of H-Arg(Tos)-Asp(OBzl)-OMe and H-Arg(Tos)-Glu(OBzl)-OMe suffer transesterification, while beta-t-butyl or beta-cyclohexyl esters are stable under the same conditions. In spite of the simple structure, all compounds bind selectively to the alpha(v)beta(3) integrin receptor, 3 showing the highest affinity with an IC(50) value of 0.74 microM value. On the other hand only 3 binds with measurable activity to the alpha(IIb)beta(3) receptor (IC(50) 159 microM). The binding affinities seem to be in accordance with the distances between the arginine guanidino and the aspartic acid carboxyl group in extended conformation determined by semiempirical geometry optimization. 相似文献
6.
Cristina Chiva Marta Vilaseca Ernest Giralt Fernando Albericio 《Journal of peptide science》1999,5(3):131-140
DKP formation is a serious side reaction during the solid‐phase synthesis of peptide acids containing either Pro or Gly at the C‐terminus. This side reaction not only leads to a lower overall yield, but also to the presence in the reaction crude of several deletion peptides lacking the first amino acids. For the preparation of protected peptides using the Fmoc/tBu strategy, the use of a ClTrt‐Cl‐resin with a limited incorporation of the C‐terminal amino acid is the method of choice. The use of resins with higher loading levels leads to more impure peptide crudes. The use of HPLC‐ESMS is a useful method for analysing complex samples, such as those formed when C‐terminal Pro peptides are prepared by non‐optimized solid‐phase strategies. Copyright © 1999 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
7.
8.
The structure of a novel diketopiperazine metabolite, named nigrifortine, isolated from cultures of Penicillium nigricans is deduced from its 1H NMR, mass and UV spectra together with biosynthetic reasoning. 相似文献
9.
The solid-phase synthesis of peptides derived from the sterically hindered -hydroxymethylserine (HmS) was investigated. The acid-sensitive, O,O-isopropylidene (Ipr) protection of HmS is compatible with the Fmoc chemistry, represented here by the Fmoc-HmS(Ipr)-OH and Fmoc-HmS(Ipr)-F derivatives. Three analogs of the opioid pentapeptide DADLE with a single or two consecutive HmS residue(s) were synthesized using Wang resin as the solid support. The HATU method has been shown to effectively accomplish difficult couplings with the HmS(Ipr) residue. Wang resin is not suitable for the synthesis of sequences with a C-terminal HmS because of the easy formation of the diketopiperazine resulting from the cyclization of the susceptible dipeptide sequence AA-HmS(Ipr) bound to the resin. A further drawback of the Wang resin methodology is the increased danger of the undesired NO-acyl shift, when long-lasting acidic cleavage is applied. These side reactions are totally suppressed when the 2-chlorotrityl polystyrene is used as a solid support. The mild conditions (AcOH/TFE/DCM) applied for the peptide detachment from this resin do not affect the Ipr protection, affording highly pure fragments with HmS(Ipr) residues suitable for post-cleavage condensation, cyclization or controlled side-chain deprotection. This approach is documented by the efficient synthesis of linear and cyclic analogs of the opioid hexapeptide DTLET containing two residues of HmS or HmS(Ipr) in positions 2 and 6. 相似文献
10.
Diketopiperazines in peptide and combinatorial chemistry. 总被引:2,自引:0,他引:2
Peter M Fischer 《Journal of peptide science》2003,9(1):9-35
Diketopiperazines (DKPs), the smallest cyclic peptides, represent an important class of biologically active natural products and their research has been fundamental to many aspects of peptide chemistry. The advent of combinatorial chemistry has revived interest in DKPs for two reasons: firstly, they are simple heterocyclic scaffolds in which diversity can be introduced and stereochemically controlled at up to four positions; secondly, they can be prepared from readily available alpha-amino acids using very robust chemistry. Here synthetic methods, conformation, as well as applications of DKPs are summarized and discussed critically. 相似文献