Search results for "phenylalanine"
showing 10 items of 193 documents
Tarantula Hemocyanin Shows Phenoloxidase Activity
1998
An enzyme generally catalyzes one well defined reaction with high specificity and efficiency. We report here in contrast that the copper protein hemocyanin of the tarantula Eurypelma californicum exhibits two different functions. These occur at the same active site. While hemocyanin usually is an oxygen carrier, its function can be transformed totally to monophenoloxidase and o-diphenoloxidase activity after limited proteolysis with trypsin or chymotrypsin. N-acetyldopamine (NADA) is more effectively oxidized than L-dopa or dopamine. This irreversible functional switch of tarantula hemocyanin function is limited to the two subunits b and c of its seven subunit types. A conserved phenylalani…
Conformational investigation of ?,?-dehydropeptides.N-acetyl-(E)-dehydrophenylalanineN?-methylamide: conformational properties from infrared and theo…
2005
N-Acetyl-(E)-dehydrophenylalanine N'-methylamide [Ac-(E)-DeltaPhe-NHMe], one of a few representative (E)-alpha,beta-dehydroamino acids, was studied by FTIR in dichloromethane and acetonitrile. To support spectroscopic interpretations and to gain some deeper insight into the Ac-(E)-DeltaPhe-NHMe molecule, the Ramachandran potential energy surface was calculated by the B3LYP/6-31G*//HF/3-21G method and the conformers localized were fully optimized at the B3LYP/6-31 + G** level. The spectra and calculations were compared with those of the related molecules Ac-DeltaAla-NHMe and Ac-(Z)-DeltaPhe-NHMe. The title compound assumes two conformational states in equilibrium in dichloromethane solution …
β-turn tendency in N-methylated peptides with dehydrophenylalanine residue: DFT study.
2010
The tendency to adopt β-turn conformation by model dipeptides with α,β-dehydrophenylalanine (ΔPhe) residue in the gas phase and in solution is investigated by theoretical methods. We pay special attention to a dependence of conformational properties on the side-chain configuration of dehydro residue and the influence of N-methylation on β-turn stability. An extensive computational study of the conformational preferences of Z and E isomers of dipeptides Ac-Gly-(E/Z)-ΔPhe-NHMe (1a / 1b) and Ac-Gly-(E/Z)-ΔPhe-NMe(2) (2a/2b) by B3LYP/6-311++G(d,p) and MP2/6-311++G(d,p) methods is reported. It is shown that, in agreement with experimental data, Ac-Gly-(Z)-ΔPhe-NHMe has a great tendency to adopt …
Substituted phosphonic analogues of phenylglycine as inhibitors of phenylalanine ammonia lyase from potatoes.
2018
A series of phosphonic acid analogues of phenylglycine variously substituted in phenyl ring have been synthesized and evaluated for their inhibitory activity towards potato l-phenylalanine ammonia lyase. Most of the compounds appeared to act as moderate (micromolar) inhibitors of the enzyme. Analysis of their binding performed using molecular modeling have shown that they might be bound either in active site of the enzyme or in the non-physiologic site. The latter one is located in adjoining deep site nearby the to the entrance channel for substrate into active site.
Experimental and theoretical NMR studies of interaction between phenylalanine derivative and egg yolk lecithin
2014
The interaction of phenylalanine diamide (Ac-Phe-NHMe) with egg yolk lecithin (EYL) in chloroform was studied by 1H and 13C NMR. Six complexes EYL–Ac-Phe-NHMe, stabilized by N–H···O or/and C–H···O hydrogen bonds, were optimized at M06-2X/6-31G(d,p) level. The assignment of EYL and Ac-Phe-NHMe NMR signals was supported using GIAO (gauge including atomic orbital) NMR calculations at VSXC and B3LYP level of theory combined with STO-3Gmag basis set. Results of our study indicate that the interaction of peptides with lecithin occurs mainly in the polar ‘head’ of the lecithin. Additionally, the most probable lecithin site of H-bond interaction with Ac-Phe-NHMe is the negatively charged oxygen in …
Toward engineering efficient peptidomimetics. Screening conformational landscape of two modified dehydroaminoacids
2013
Effective peptidomimetics should posses structural rigidity and appropriate interaction pattern leading to potential spatial and electronic matching to the target receptor site. Rational design of such small bioactive molecules could push chemical synthesis and molecular modeling toward faster progress in medicinal chemistry. Conformational properties of N-t-butoxycarbonyl-glycine-(E/Z)-dehydrophenylalanine N′,N′-dimethylamides (Boc-Gly-(E/Z)-ΔPhe-NMe2) in chloroform were studied by NMR and IR spectroscopy. The experimental findings were supported by extensive calculations at DFT(B3LYP, M06-2X) and MP2 levels of theory and the β-turn tendency for both isomers of the studied dipeptide were d…
CCDC 201880: Experimental Crystal Structure Determination
2007
Related Article: S.Schwarz-Barac, H.Ritter, D.Schollmeyer|2003|Macromol.Rapid Commun.|24|325|doi:10.1002/marc.200391325
Influence of anti-inflammatory flavonoids on degranulation and arachidonic acid release in rat neutrophils.
1994
We assessed the effects of 24 flavonoid derivatives, reported as anti-inflammatory, on lysosomal enzyme secretion and arachidonic acid release in rat neutrophils. Amentoflavone, quercetagetin- 7-O -glucoside, apigenin, fisetin, kaem pferol, luteolin and quercetin were the most potent inhibitors of β-glucuronidase and lysozyme release. The first com pound was also able to inhibit basal release. These flavonoids besides chrysin and to a reduced extent, naringenin, significantly inhibited arachidonic acid release from membranes. A correlation between degranulation and arachidonic acid release was found for this series of compounds. Structureactivity relationships and implications for the anti-…
Conformational properties of N′,N′-dimethylamides of N-acetyldehydroalanine and N-acetyl-(Z)-dehydrophenylalanine
2001
Conformational preferences of Ac-deltaAla-NMe2 and Ac-(Z)-deltaPhe-NMe2 were studied and compared with those of their monomethyl counterparts as well as with those of their saturated analogues. X-Ray data and energy calculations revealed a highly conservative conformation of the dehydro dimethylamides, which is located in a high-energy region of the Ramachandran map.
Phenylalanine Hydroxylase Participation in the Synthesis of Serotonin and Pteridines in Drosophila melanogaster
1997
Abstract Phenylalanine hydroxylase is involved in the synthesis of serotonin and pteridines, probably catalysing the hydroxylation of tryptophan and a tetrahydropterin oxidase reaction, respectively. Supplementation of the wild-type Drosophila diet with either L-Phe or L-Trp induced a significant increase in the phenylalanine hydroxylase concentration, while L-Tyr supplementation had no effect. The level of serotonin in adult heads of the PAH-defective mutant Henna recessive-3 was significantly lower than that obtained for the wild-type strain. A 4-fold increase in the concentration of phenylalanine hydroxylase is observed during the pharate adult head development. It occurs in parallel wit…