共查询到20条相似文献,搜索用时 31 毫秒
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J. Hlaváček J. Pícha V. Vaněk J. Jiráček J. Slaninová V. Fučík M. Buděšínský D. Gilner R. C. Holz 《Amino acids》2010,38(4):1155-1164
A series of N
α-acyl (alkyl)- and N
α-alkoxycarbonyl-derivatives of l- and d-ornithine were prepared, characterized, and analyzed for their potency toward the bacterial enzyme N
α-acetyl-l-ornithine deacetylase (ArgE). ArgE catalyzes the conversion of N
α-acetyl-l-ornithine to l-ornithine in the fifth step of the biosynthetic pathway for arginine, a necessary step for bacterial growth. Most of the
compounds tested provided IC50 values in the μM range toward ArgE, indicating that they are moderately strong inhibitors. N
α-chloroacetyl-l-ornithine (1g) was the best inhibitor tested toward ArgE providing an IC50 value of 85 μM while N
α-trifluoroacetyl-l-ornithine (1f), N
α-ethoxycarbonyl-l-ornithine (2b), and N
α-acetyl-d-ornithine (1a) weakly inhibited ArgE activity providing IC50 values between 200 and 410 μM. Weak inhibitory potency toward Bacillus subtilis-168 for N
α-acetyl-d-ornithine (1a) and N
α-fluoro- (1f), N
α-chloro- (1g), N
α-dichloro- (1h), and N
α-trichloroacetyl-ornithine (1i) was also observed. These data correlate well with the IC50 values determined for ArgE, suggesting that these compounds might be capable of getting across the cell membrane and that
ArgE is likely the bacterial enzymatic target. 相似文献
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4.
Fibromodulin from bovine articular cartilage has been subjected to lectin affinity chromatography by Sambucus nigra lectin which binds α(2-6)- linked N-acetylneuraminic acid, and the structure of the keratan sulphate in the binding and non-binding fractions examined by keratanase
II digestion and subsequent high pH anion exchange chromatography. It has been confirmed that the keratan sulphate chains
attached to fibromodulin isolated from bovine articular cartilage may have the chain terminating N-acetylneuraminic acid residue α(2-3)- or α(2-6)-linked to the adjacent galactose residue. Although the abundance of α(2-6)-linked
N-acetylneuraminic acid (ca. 22%) is such that this could cap one of the four chains in almost all fibromodulin molecules, it was found that ca. 34% of the fibromodulin proteoglycan molecules from bovine articular cartilage were capped exclusively with α(2-3)-linked
N-acetylneuraminic acid. The remainder of the fibromodulin proteoglycans, which bound to the lectin had a mixture of α(2-3)-
and α(2-6)-linked N-acetylneuraminic acid capping structures. The keratan sulphates attached to fibromodulin molecules capped exclusively with
α(2-3)- linked N-acetylneuraminic acid were found to have a higher level of galactose sulphation than those from fibromodulin with both α(2-3)-
and α(2-6)-linked N-acetylneuraminic acid caps, which bound to the Sambucus nigra lectin. In addition, both pools contained chains of similar length (ca. 8–9 disaccharides). Both also contained α(1-3)-linked fucose, showing that this feature does not co-distribute with α(2-6)-linked
N-acetylneuraminic acid, although these two features are present only in mature articular cartilage. These data show that there
are discrete populations of fibromodulin within articular cartilage, which may have differing impacts upon tissue processes. 相似文献
5.
Alessandro Moretto Marta De Zotti Marco Crisma Fernando Formaggio Claudio Toniolo 《International journal of peptide research and therapeutics》2008,14(4):307-314
“Mono-N-methyl scan” is a rational approach for the optimization of the peptide biological properties. N-Methylation of the –CONH– functionality is also a useful tool for discriminating solvent exposed from intramolecularly H-bonded
secondary amide groups in peptides. We are currently extending this reaction to linear peptides based on Cα-tetrasubstituted α-amino acids. Following our study on the synthesis and conformation of the mono-N-methylated peptides from Cα-methylated residues, in this work we investigated the N-methylation reaction on homo-peptides to the pentamer level from the Cα-ethylated residue Cα,α-diethylglycine. Under the classical experimental conditions used, exclusively mono-N-methylation (on the N-terminal, acetylated residue) takes place, as unambiguously shown by mass spectrometry, 2D-NMR, and X-ray diffraction techniques.
This backbone modification does not seem to involve any significant change in the peptide conformation in the crystalline
state.
Dedicated to the memory of Prof. Miroslav T. Leplawy (Technical University of Łodz, Poland), who performed the first synthesis
of the extremely sterically demanding Cα,α-diethylglycine peptides. 相似文献
6.
Background
Thymosin α1 (Tα1), a 28-amino acid N α -acetylated peptide, has a powerful general immunostimulating activity. Although biosynthesis is an attractive means of large-scale manufacture, to date, Tα1 can only be chemosynthesized because of two obstacles to its biosynthesis: the difficulties in expressing small peptides and obtaining N α -acetylation. In this study, we describe a novel production process for N α -acetylated Tα1 in Escherichia coli. 相似文献7.
Kyoung-Soon Jang Woo-Jae Chung Hyun-Ki Kim Yun-Gon Kim Yoon-Sik Lee Byung-Gee Kim 《Biotechnology and Bioprocess Engineering》2008,13(4):445-452
A novel α-Gal resin was chemo-enzymatically synthesized for the efficient adsorption of anti-α-Gal antibodies in human serum
for xenotransplantation. To covalently conjugate a hexanoate linker with lactose and N-acetylglucosamine, both acceptor sugars were acetylated and brominated. Then, α-and β-galactoses were sequentially added
to the linker-containing saccharides at their non-reducing ends by using recombinant α-(1,3)-and β-(1,4)-galactosyltransferases
from E. coli. Finally, the synthesized α-Gal derivatives were immobilized on HiCore, a core-shell type resin, that was functionalized with amino groups on the shell region, as a packing material on-column.
Using this method we were able to demonstrate that the α-Gal HiCore resin had a reduced level of non-specific protein adsorption compared with the commercially available polystyrene supports,
TentaGel, and agarose-based supports, when Lectin BS-I was used as the model binding protein. Furthermore, the α-Gal HiCore resin was more efficient at eliminating anti-α-Gal IgGs from the total human IgGs through immunoadsorption than the other
two α-Gal resins, α-Gal TentaGel and α-Gal agarose. The α-Gal HiCore resin developed in this study can be utilized in a wide range of applications including ex vivo immunoadsorption and as a quantitative assay of anti-Gal antibody in human sera. 相似文献
8.
Summary. A concise preparation of N
α-Fmoc-N
ɛ-(Boc, methyl)-lysine and its application in the synthesis of site-specifically lysine monomethylated peptide is described.
N
α-Fmoc-N
ɛ-(Boc, methyl)-lysine is obtained, via consecutive reductive benzylation and reductive methylation in a one-pot reaction,
followed by debenzylation through catalytic hydrogenolysis and Boc protection in another one-pot reaction. A peptide containing
monomethylated lysine is successfully synthesized by incorporating N
α-Fmoc-N
ɛ-(Boc, methyl)-lysine as a building block via solid-phase peptide synthesis. 相似文献
9.
J. Custot Jean-Luc Boucher Sandrine Vadon Catherine Guedes Sylvie Dijols Marcel Delaforge Daniel Mansuy 《Journal of biological inorganic chemistry》1996,1(1):73-82
The effects of various compounds bearing an N-OH group such as N-hydroxy-guanidines, amidoximes, and hydroxylamines, on bovine and rat liver arginases was studied. Some of these compounds
with an l-α-amino acid function at an appropriate distance from the N-OH group acted as strong competitive liver arginase inhibitors,
displaying Ki values between 4 and 150 μM. Two compounds, N
ε-hydroxy-l-lysine and N
ω-hydroxy-d,l-indospicine, which exhibited Ki values of 4 and 20 μM (at pH 7.4), were the most potent inhibitors of arginase described
to date. The distance between the α-amino acid and N-OH functions appeared to be crucial for potent inhibition of arginase,
as N
δ-hydroxy-l-ornithine, which has one -CH2 group less than N
ε-hydroxy-l-lysine, exhibited a 37-fold higher Ki value than N
ε-hydroxy-l-lysine. Based on these results, a model for the interaction of N
ω-hydroxyamino-l-α-amino acids with the arginase active site is proposed. This model involves the binding of the N-OH group of the inhibitors
to the arginase Mn(II) center and suggests that N
ε-hydroxy-l-lysine is a good transition state analog of arginase. 相似文献
10.
Beltrán Maite Maseda Marta Robles Jordi Pedroso Enrique Grandas Anna 《International journal of peptide research and therapeutics》1997,4(3):147-155
Summary Covalently linked peptide-oligonucleotide hybrids are good candidates for antisense or anti-gene therapeutics. The use of
homoserine as the linking amino acid allows nucleopeptide analogues with a base-stable amino acid-nucleoside phosphate diester
linkage to be obtained. Three Nα, O-protected homoserine derivatives (N
α-Boc-Hse(DMT)-O− HTEA+ (I),N
α-Fmoc-Hse(MMT)-O−Hpyr+ (II) andN
α-Phac-Hse(DMT)-O−HTEA+(III) were prepared after transient silylation,N
α-acylation, desilylation and protection of the hydroxyl group. The first can be placed at any position in the peptide sequence,
while the other two must be placed at theN-terminus to afford nucleopeptides with the N-terminal amine group free or permanently blocked, respectively. 相似文献
11.
J. Ogawa A. Ryono S. -X. Xie R. M. Vohra R. Indrati H. Miyakawa T. Ueno Y. Ikenaka H. Nanba S. Takahashi S. Shimizu 《Applied microbiology and biotechnology》1999,52(6):797-801
N-Carbamoyl-d-α-amino acid amidohydrolase (d-carbamoylase) was found to distinguish stereochemistry not only at the α-carbon but also at the β-carbon of N-carbamoyl-d-α-amino acids. The enzyme selectively acted on one of the four stereoisomers of N-carbamoyl-α,β-diastereomeric amino acids. This simultaneous recognition of two chiral centers by d-carbamoylase was useful for the fine stereoselective synthesis of α,β-diastereomeric amino acids such as threonine, isoleucine,
3,4-methylenedioxyphenylserine and β-methylphenylalanine. The stereoselectivity for the β-carbon was influenced by the pH
of the reaction mixture and by the bulk of the substituent at the β-carbon.
Received: 18 June 1999 / Received revision: 30 July 1999 / Accepted: 6 August 1999 相似文献
12.
L. A. Simeoni N. E. Byramova N. V. Bovin 《Russian Journal of Bioorganic Chemistry》2000,26(3):183-191
The first synthesis of the Neu5Gc analogue of SiaT
n
disaccharide, which can be detected in breast tumors by immunochemical methods, is reported. The regioselective sialylation
of (3-trifluoroacetamidopropyl)-2-azido-2-deoxy-α-D-galactopyranoside with peracetate of the methyl ester ofN-acetoxyacetyl-neuraminic acid β-ethylthioglycoside in the presence ofN-iodosuccinimide and trifluoromethanesulfonic acid (or its trimethylsilyl ester) resulted in the derivatives of α- and β-sialyl(2→6)galactosaminide
in 39 and 32% yields, respectively. The catalytic hydrogenolysis of the azido group and subsequentN- andO-acetylation of the α-anomer gave the peracetate of trifluoroacetamidopropyl glycoside. Removal of the protective groups led
to glycoside Neu5Gcα2→6GalNAcα-O(CH2)3NH2. Using the Neu5Gc derivative with acetoxyacetyl groups at positions O9 and O4 as a donor increases the α-selectivity of sialylation
to afford the α- and β-anomers in 69 and 8% yields, respectively. 相似文献
13.
Soussilane P Soussillane P D'Alessio C Paccalet T Fitchette AC Parodi AJ Williamson R Plasson C Faye L Gomord V 《Glycoconjugate journal》2009,26(5):609-607
Glucosidase II, one of the early N-glycan processing enzymes and a major player in the glycoprotein folding quality control, has been described as a soluble
heterodimer composed of α and β subunits. Here we present the first characterization of a plant glucosidase II α subunit at
the molecular level. Expression of the Arabidopsis α subunit restored N-glycan maturation capacity in Schizosaccharomyces pombe α− or αβ−deficient mutants, but with a lower efficiency in the last case. Inactivation of the α subunit in a temperature
sensitive Arabidopsis mutant blocked N-glycan processing after a first trimming by glucosidase I and strongly affected seedling development.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Cecilia D’Alessio and Thomas Paccalet have equal contributions to this work
An erratum to this article can be found at 相似文献
14.
4-Methylumbelliferyl N-acetyllactosaminide and 4-methylumbelliferyl sialyl N-acetyllactosaminides, which are used for the assay of sialytransferase, neuraminidase and fucosyltransferase, were synthesized,
respectively, by the β-D-galactosidase from Bacillus circulans and by a recombinant rat α2,3-(N)-sialyltransferase or rat liver α2,6-(N)-sialyltransferase with CMP-N-acetylneuraminic acid as donor. 相似文献
15.
Jan Pícha Miloš Buděšínský Pavel Fiedler Miloslav Šanda Jiří Jiráček 《Amino acids》2010,39(5):1265-1280
In the present study, we describe in detail the synthesis of a relatively rare class of phosphorus compounds, α-carboxyphosphinopeptides.
We prepared several norleucine-derived α-carboxyphosphinic pseudopeptides of the general formula Nle-Ψ[PO(OH)]-Gly. These
compounds could have important applications as transition state-mimicking inhibitors for methionine or leucine aminopeptidases
or other enzymes. For the preparation of the key α-carboxyphosphinate protected precursors, we investigated, compared and
improved two different synthetic methods described in literature: the Arbuzov reaction of a silylated N-protected phosphinic acid with a bromoacetate ester and the nucleophilic addition of a mixed O-methyl S-phenyl N-protected phosphonic acid or a methyl N-protected phosphonochloridate with tert-butyl lithioacetate. We also prepared two N-Fmoc protected synthons, Fmoc-Nle-Ψ[PO(OH)]-Gly-COOH and Fmoc-Nle-Ψ[PO(OAd)]-Gly-COOH, and demonstrated that these precursors
are suitable building blocks for the solid-phase synthesis of α-carboxyphosphinopeptides. 相似文献
16.
Pseudomonas fluorescens NCIMB 11671 metabolises α-pinene via α-pinene oxide and 2-methyl-5-isopropylhexa-2,5-dienal. Mutants unable to grow on α-pinene
and/or α-pinene oxide have been isolated by N-methyl-N′-nitro-N-nitrosoguanidine mutagenesis, including an unexpected phenotype able to grow on α-pinene but not on α-pinene oxide. The mutants
have been classified on the basis of their α-pinene monooxygenase, α-pinene oxide lyase and aldehyde dehydrogenase activities.
Biotransformation of α-pinene by the wild-type and mutant strains has revealed evidence for alternative routes for pinene
metabolism to that already proposed.
Received: 24 August 1995/Received revision: 20 December 1995/Accepted: 8 January 1996 相似文献
17.
Veronique Maes Dirk Tourwé 《International journal of peptide research and therapeutics》2006,12(3):197-202
The retro-N
α-carboxymethyl histidine moiety, short (N
αHis)Ac, functions as an efficient chelator for the 99mTc(CO)3 core which allows the labeling of the peptides with a very high specific activity. However as a general consequence of the neutral [99mTc(CO)3] (N
αHis)Ac-complex, undesired accumulation in kidney and liver may be high. In order to improve the pharmacokinetic properties of the radiolabeled peptides containing this chelate, attempts have been made to conjugate a carbohydrate using the Maillard reaction. Since the (N
αHis)Ac moiety has an unusually reactive N
α, various chemical strategies have been explored to perform the Maillard reaction followed by the Amadori rearrangement on peptides containing this chelator. This indicated that a selective protection of the secondary nitrogen in the chelator is necessary.Australian Peptide Conference Issue. 相似文献
18.
Unravelling the complex correlation between chemical shifts of 13
C
α, 13
C
β, 13
C′, 1
H
α, 15
N, 1
H
N
atoms in amino acids of proteins from NMR experiment and local structural environments of amino acids facilitates the assignment
of secondary structures of proteins. This is an important impetus for both determining the three-dimensional structure and
understanding the biological function of proteins. The previous empirical correlation scores which relate chemical shifts
of 13
C
α, 13
C
β, 13
C′, 1
H
α, 15
N, 1
H
N
atoms to secondary structures resulted in progresses toward assigning secondary structures of proteins. However, the physical-mathematical
framework for these was elusive partly due to both the limited and orthogonal exploration of higher-dimensional chemical shifts
of hetero-nucleus and the lack of physical-mathematical understanding underlying those correlation scores. Here we present
a simple multi-dimensional hetero-nuclear chemical shift score function (MDHN-CSSF) which captures systematically the salient
feature of such complex correlations without any references to a random coil state of proteins. We uncover the symmetry-breaking
vector and its reliability order not only for distinguishing different secondary structures of proteins but also for capturing
the delicate sensitivity interplayed among chemical shifts of 13
C
α, 13
C
β, 13
C′, 1
H
α, 15
N, 1
H
N
atoms simultaneously, which then provides a straightforward framework toward assigning secondary structures of proteins.
MDHN-CSSF could correctly assign secondary structures of training (validating) proteins with the favourable (comparable) Q3
scores in comparison with those from the previous correlation scores. MDHN-CSSF provides a simple and robust strategy for
the systematic assignment of secondary structures of proteins and would facilitate the de novo determination of three-dimensional
structures of proteins. 相似文献
19.
Profiling of carbohydrate structures on cell membranes has been difficult to perform because of the complexity and the variations
of such structures on cell surface glycans. This study presents a novel method for rapid profiling of cell surface glycans
for terminal N-acetyllactosamines (Galβ1-(3)4GlcNAc-R) that are uncapped, capped with sialic acid as SA-Galβ1-(3)4GlcNAc-R, or with α1,3galactosyls
as the α-gal epitope- Galα1-3Galβ1-(3)4GlcNAc-R. This method includes two enzymatic reactions: (1) Terminal sialic acid is
removed by neuraminidase, and (2) α-gal epitopes are synthesized on the exposed N-acetyllactosamines by α1,3galactosyltransferase. Existing and de novo synthesized α-gal epitopes on cells are quantified by a modification of radioimmunoassay designated as “ELISA inhibition
assay,” which measures binding of the monoclonal anti-Gal antibody M86 to α-gal epitopes. This binding is proportional to
the number of cell surface α-gal epitopes. The amount of free M86 antibody molecules remaining in the solution is determined
by ELISA using synthetic α-gal epitopes linked to albumin as solid phase antigen. The number of α-gal epitopes on cells is
estimated by comparing binding curves of M86 incubated with the assayed cells, at various concentrations of the cells, with
the binding of M86 to rabbit red cells expressing 2 × 106 α-gal epitopes/cell. We could demonstrate large variations in the number of sialic acid capped N-acetyllactosamines, α-gal epitopes and uncapped N-acetyllactosamines on different mammalian red blood cells, and on nucleated cells originating from a given tissue in various
species. This method may be useful for rapid identification of changes in glycosylation patterns in cells subjected to various
treatments, or in various states of differentiation. 相似文献
20.
Summary A Monte Carlo simulation is proposed to study the dynamics of helper T-cells (N
H) and viral (N
V) populations in an immune response model relevant to HIV. Cellular states are binary variables and the interactions are described
by logical expressions. Viral population shows a nonmonotonic growth before reaching a constant value while helper T-cells
grow to a constant after a relaxation/reaction time. Initially, the population of helper cells grows with time with a power-law,
N
H ∼t
β, before reaching the steady-state; the growth exponent β increases systematically (β ≈ 1 – 2) with the mutation rate (P
mut≈0.1–0.4). The critical recovery time (t
c) increases exponentially with the viral mutation, t
c≈Ae
αP
mut
, with α=4.52±0.29 in low mutation regime and α=15.21±1.41 in high mutation regime. The equilibrium population of helper T-cell
declines slowly with P
mut and collapses at ∼ 0.40; the viral population exhibits a reverse trend, i.e., a slow increase before the burst around the
same mutation regime. 相似文献