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1.
Carl Henrik Grbitz Lars Male Hartviksen 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(3):o171-o176
The crystal structures of the four dipeptides l ‐seryl‐l ‐asparagine monohydrate, C7H13N3O5·H2O, l ‐seryl‐l ‐tyrosine monohydrate, C12H16N2O5·H2O, l ‐tryptophanyl‐l ‐serine monohydrate, C14H17N3O4·H2O, and l ‐tyrosyl‐l ‐tryptophan monohydrate, C20H21N3O4·H2O, are dominated by extensive hydrogen‐bonding networks that include cocrystallized solvent water molecules. Side‐chain conformations are discussed on the basis of previous observations in dipeptides. These four dipeptide structures greatly expand our knowledge on dipeptides incorporating polar residues such as serine, asparagine, threonine, tyrosine and tryptophan. 相似文献
2.
Carl Henrik Grbitz 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):500-502
A new `rule' for the association of hydrogen‐bond donors and acceptors in crystal structures is presented. It implies that ranks are assigned to each donor and each acceptor (1 is best, 2 is next best etc.), and that hydrogen bonds should be formed between donors and acceptors in rank order. l ‐Ser‐l ‐Ala, C6H12N2O4, is used together with its retroanalogue, l ‐Ala‐l ‐Ser, and three other pairs of dipeptide retroanalogues to illustrate this rule and the reasons why it may not always be followed. 相似文献
3.
Hadgu Girmay Gebreslasie
yvind Jacobsen Carl Henrik Grbitz 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(9):o359-o363
The title compound [systematic name (6S,12S)‐methyl 6‐(allyloxymethyl)‐12‐isopropyl‐2,2,9,9‐tetramethyl‐4,7,10‐trioxo‐3‐oxa‐5,8,11‐triazatridecan‐13‐oate], C21H37N3O7, containing the little studied O‐allyl‐l ‐serine residue [Ser(All)], crystallizes in the monoclinic space group C2 with one molecule in the asymmetric unit. The compound is an analogue of the Ser140‐Val142 segment of the water channel aquaporin‐4 (AQP4). It forms a distorted type‐II β‐turn with a PII–310L–PII backbone conformation (PII is polyproline II). The overall backbone conformation is markedly different from that of the CO(Pro139)–Val142 stretch of rat AQP4, but is quite similar to the corresponding segment of human AQP4, despite significant differences at the level of the individual residues. The side chain of the Ser(All) residue adopts a gauche conformation relative to the backbone CO—Cα and Cα—N bonds. The H atoms of the two CH2 groups in the Ser(All) side chain are almost eclipsed. The crystal packing of the title compound is divided into one‐molecule‐thick layers, each layer having a hydrophilic core and distinct hydrophobic interfaces on either side. 相似文献
4.
Carl Henrik Grbitz 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(12):1496-1498
One of the amino H atoms of l ‐phenylalanyl‐l ‐valine, C14H20N2O3, participates in a rare secondary interaction in being accepted by the aromatic ring of the phenylalanine side chain. The phenyl group is also a donor in a weak hydrogen bond to the peptide carbonyl group. 相似文献
5.
Hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry method for the simultaneous determination of l‐valine,l‐leucine,l‐isoleucine,l‐phenylalanine,and l‐tyrosine in human serum 下载免费PDF全文
Beibei Gao Qingyun Yuanzi Hongwen Zhang Yongqing Wang Ning Ou Hongwen Zhou 《Journal of separation science》2015,38(22):3876-3883
l ‐Valine, l ‐leucine, l ‐isoleucine, l ‐phenylalanine, and l ‐tyrosine are important proposed biomarkers for the early detection and diagnosis of type 2 diabetes. A simple and selective hydrophilic interaction chromatography with tandem mass spectrometry method was developed for the simultaneous determination of these amino acids in human serum, using stable isotope‐labeled amino acids as internal standards. Chromatographic separation was carried out on a Syncronis HILIC column (150 mm × 2.1 mm, 5 μm) with the column temperature of 35°C and a mobile phase consisted of acetonitrile/120 mM ammonium acetate (89:11, v/v), and the run time was 11.0 min. The mass spectrometric analysis was performed using a QTRAP 5500 mass spectrometer coupled with an electrospray ionization source in positive ion mode. As these five amino acids are endogenous compounds in serum, we used the corresponding stable isotope‐labeled amino acids to evaluate the matrix effect and recovery in serum. The matrix effect was 98.7–107.3%, and the recovery was 92.7–102.3%. Calibration curves spiked unlabeled amino acids in water were linear over the range of 0.200–100 μg/mL. The accuracy, inter‐, and intraday precision were below 10.2%. Analytes were stable during the study. This assay method has been validated and applied to the early diagnosis research of type 2 diabetes. 相似文献
6.
Marius Bruvoll Selma Dizdarevic Nina Fimland Jasmina Hafizovic Carl Henrik Grbitz Helen Therese Kalfjs Kristian Vestli Alexander Krivokapic 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(1):o22-o25
The structures of the title dipeptides, C9H18N2O4·0.33H2O, C12H16N2O4 and C8H16N2O4S·0.34H2O, complete a series of investigations focused on l ‐Xaa‐l ‐serine peptides, where Xaa is a hydrophobic residue. All three structures are divided into hydrophilic and hydrophobic layers. The hydrophilic layers are thin for l ‐phenylalanyl‐l ‐serine, rendered possible by an unusual peptide conformation, and thick for l ‐isoleucyl‐l ‐serine and l ‐methionyl‐l ‐serine, which include cocrystallized water molecules on the twofold axes. 相似文献
7.
Carl Henrik Grbitz Silja Agustsdottir Francesca Bleken 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(1):o58-o60
The title peptide, C7H14N2O3, crystallizes with seven independent molecules in the asymmetric unit. All have essentially the same overall conformation, but some flexibility is exhibited by the glycine residue. It appears that the high Z′ value, observed only three times before for an organic compound, permits formation of shorter hydrogen bonds in one of the two head‐to‐tail chains involving the N‐terminal amino groups and the C‐terminal carboxylate groups than found in a hypothetical model structure of glycyl‐l ‐valine with Z′ = 1, and that it furthermore alleviates strain associated with an eclipsed orientation of the amino group. 相似文献
8.
Arne Johansen Randi Midtkandal Heidi Roggen Carl Henrik Grbitz 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(4):o198-o200
The valine side chains in the crystal structure of the title compound [systematic name: 2‐(2‐ammonio‐3‐methylbutanamido)‐3‐hydroxypropanoate trihydrate], C8H16N2O4·3H2O, stack along an a axis of 4.77 Å to form hydrophobic columns surrounded by remarkable water/hydroxyl shells. The peptide main chains are connected by hydrogen bonds in two‐dimensional layers. The peptide molecules in each layer are related only by translation, and generate a very rare pattern. This is rendered possible through the formation of the shortest Cα—H·O(carboxylate) interaction ever recorded. 相似文献
9.
Ina Hydal Helle Camilla Victoria Lkken Carl Henrik Grbitz Bjrn Dalhus 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(10):o771-o772
The peptide bond in the crystal structure of the title compound, C8H16N2O4, deviates substantially from planarity in the same manner as in other l ‐Ser‐l ‐Xaa dipeptides, where Xaa is a hydrophobic residue. 相似文献
10.
Carl Henrik Grbitz 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(5):o371-o373
The structure of the title compound, C15H22N2O3·2H2O, was derived from data collected on a very thin twinned needle. The peptide molecule is in a rare conformation normally associated with hydrophobic dipeptides that form nanotubes. Nevertheless, the present structure is divided into hydrophobic and hydrophilic layers. 相似文献
11.
Carl Henrik Grbitz 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(12):o730-o732
The side chains of l ‐alanyl‐l ‐methionine hemihydrate, C8H16N2O3S·0.5H2O, form hydrophobic columns within a three‐dimensional hydrogen‐bond network that includes extended polymers of cocrystallized water molecules and Cα—H⋯S interactions. 相似文献
12.
Carl Henrik Grbitz 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):575-576
A new type of molecular arrangement for dipeptides is observed in the crystal structure of l ‐phenylalanyl‐l ‐alanine dihydrate, C12H16N2O3·2H2O. Two l ‐Phe and two l ‐Ala side chains aggregate into large hydrophobic columns within a three‐dimensional hydrogen‐bond network. 相似文献
13.
Ariana Posadaz Alicia Biasutti Csar Casale Jesús Sanz Francisco Amat‐Guerri Norman A. García 《Photochemistry and photobiology》2004,80(1):132-138
The Rose Bengal‐sensitized photooxidations of the dipeptides l ‐tryptophyl‐l ‐phenylalanine (Trp‐Phe), l ‐tryptophyl‐l ‐tyrosine (Trp‐Tyr) and l ‐tryptophyl‐l ‐tryptophan (Trp‐Trp) have been studied in pH 7 water solution using static photolysis and time‐resolved methods. Kinetic results indicate that the tryptophan (Trp) moiety interacts with singlet molecular oxygen (O2(1Δg)) both through chemical reaction and through physical quenching, and that the photooxidations can be compared with those of equimolecular mixtures of the corresponding free amino acids, with minimum, if any, influence of the peptide bond on the chemical reaction. This is not a common behavior in other di‐ and polypeptides of photooxidizable amino acids. The ratio between chemical (kr) and overall (kt) rate constants for the interaction O2(1Δg)‐dipeptide indicates that Trp‐Phe and Trp‐Trp are good candidates to suffer photodynamic action, with krlkt values of 0.72 and 0.60, respectively (0.65 for free Trp). In the case of Trp‐Tyr, a lower krlkt value (0.18) has been found, likely as a result of the high component of physical deactivation of O2(1Δg) by the tyrosine moiety. The analysis of the photooxidation products shows that the main target for O2(1Δg) attack is the Trp group and suggests a much lower accumulation of kynurenine‐type products, as compared with free Trp. This is possibly because of the occurrence of another accepted alternative pathway of oxidation that gives rise to 3a‐oxidized hydrogenated pyrrolo[2,3‐b]indoles. 相似文献
14.
Graham Smith Urs D. Wermuth Jonathan M. White 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(12):o694-o698
The structures of two compounds of l ‐tartaric acid with quinoline, viz. the proton‐transfer compound quinolinium hydrogen (2R,3R)‐tartrate monohydrate, C9H8N+·C4H5O6−·H2O, (I), and the anhydrous non‐proton‐transfer adduct with quinaldic acid, bis(quinolinium‐2‐carboxylate) (2R,3R)‐tartaric acid, 2C10H7NO2·C4H6O6, (II), have been determined at 130 K. Compound (I) has a three‐dimensional honeycomb substructure formed from head‐to‐tail hydrogen‐bonded hydrogen tartrate anions and water molecules. The stacks of π‐bonded quinolinium cations are accommodated within the channels and are hydrogen bonded to it peripherally. Compound (II) has a two‐dimensional network structure based on pseudo‐centrosymmetric head‐to‐tail hydrogen‐bonded cyclic dimers comprising zwitterionic quinaldic acid species which are interlinked by tartaric acid molecules. 相似文献
15.
Carl Henrik Grbitz 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(11):o810-o812
The asymmetric unit in the crystal structure of the title compound, C15H22N2O3·0.88H2O, contains two peptide molecules with completely different conformations. The structure is divided into hydrophobic and hydrophilic layers, with channels of water molecules at the layer interface. 相似文献
16.
Carl Henrik Grbitz 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(6):o328-o330
The title compound, C20H21N3O3·0.75H2O, crystallizes as exceedingly thin fibers. The crystal packing arrangement is related to those of other hydrophobic dipeptides with phenylalanine residues, but the structure has pseudo‐tetragonal symmetry in an orthorhombic space group with four peptide molecules and three water molecules in the asymmetric unit. 相似文献
17.
M. Gary Newton Charles F. Campana Guo‐Chen Chi Doowon Lee Zhi‐Jie Liu Vasu Nair James Phillips John P. Rose B.‐C. Wang 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(8):o518-o520
The first X‐ray crystal structure of a non‐natural dinucleotide, 5′‐O‐phosphoryl‐1′‐deoxy‐2′‐isoadenylyl‐(3′ → 5′)‐cytidine 6.5‐hydrate (pIsodApC), C19H26N8O13P2·6.5H2O, belonging to a family of dinucleotides that contain an isomeric nucleoside component, is described. A complex system of hydrogen bonds between water molecules and various sites on the dinucleotide was found. All H atoms were located from electron‐density difference maps, which allowed identification of protonation sites. Compounds of this family have been found to bind at the active site of HIV integrase and to be inhibitors of this key viral enzyme. These dinucleotides are completely resistant to cleavage by exonucleases; an abnormal dihedral angle twist in an internucleotide phosphate bond revealed in the X‐ray crystal structure may be contributing to this unusual stability towards nucleases. 相似文献
18.
Lilianna Chciska Diana Frster Wolfgang Morgenroth Peter Luger 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(8):o454-o457
The low‐temperature crystal and molecular structure analyses of two modifications of l ‐alanyl‐l ‐tyrosyl‐l ‐alanine with water, C15H21N3O5·2.63H2O [(I), at 9 K], and ethanol, C15H21N3O5·C2H5O [(II), at 20 K], solvent molecules in the crystal lattice show that the overall conformations of both modifications of the title tripeptide are practically the same. Moreover, despite the presence of different solvent molecules in the crystal lattice, the specific intermolecular interactions characteristic for individual tripeptide molecules of (I) and (II) are conserved. The crystal packing of the two modifications of Ala‐Tyr‐Ala differ from each other only in the solvent region. The tight arrangements of tripeptide molecules seem to be responsible for similar displacement parameters for all non‐H atoms, despite the different distances from the molecular centre of mass. Comparison of the displacement parameters between the room‐ and low‐temperature structures shows that an average Ueq value decrease of about 80% takes place at 9 K [for (I)] and 20 K [for (II)] with respect to room temperature. 相似文献
19.
Carl Henrik Grbitz 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(8):o533-o536
The crystal structure of N‐(l ‐2‐aminobutyryl)‐l ‐alanine, C7H14N2O3, is closely related to the structure of l ‐alanyl‐l ‐alanine, both being tetragonal, while the retro‐analogue 2‐(l ‐alanylamino)‐l ‐butyric acid 0.33‐hydrate, C7H14N2O3·0.33H2O, forms a new type of molecular columnar structure with three peptide molecules in the asymmetric unit. 相似文献
20.
Diana Frster Marc Messerschmidt Peter Luger 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(7):o420-o421
The X‐ray crystal structure of the title compound, C8H15N3O4·H2O, at 20 K (space group P21) reveals that the molecular conformation of the tripeptide is remarkably different from the water‐free form (space group P212121) reported previously [Padiyar & Seshadri (1996), Acta Cryst. C 52 , 1693–1695]. 相似文献