The role of aromatic side chains on the supramolecular hydrogelation of naphthalimide/dipeptide conjugates

2018 ◽  
Vol 42 (6) ◽  
pp. 4443-4449 ◽  
Author(s):  
Shu-Min Hsu ◽  
Rajan Deepan Chakravarthy ◽  
Hsun Cheng ◽  
Fang-Yi Wu ◽  
Tsung-Sheng Lai ◽  
...  
Keyword(s):  
Amino Acid ◽  
Side Chain ◽  
Side Chains ◽  
Amino Acid Side Chain ◽  
Aromatic Side Chains

This study demonstrates the influence of an amino-acid side chain of NI-dipeptides on supramolecular hydrogelation and biocompatibility.

scholarly journals Free Energy Landscape and Rate Estimation of the Aromatic Ring Flips in Basic Pancreatic Trypsin Inhibitor Using Metadynamics

2021 ◽  
Author(s):  
Pär Söderhjelm ◽  
Mandar Kulkarni
Keyword(s):  
Free Energy ◽  
Trypsin Inhibitor ◽  
Side Chain ◽  
Side Chains ◽  
Aromatic Residues ◽  
Basic Pancreatic Trypsin Inhibitor ◽  
Pancreatic Trypsin Inhibitor ◽  
Energy Surfaces ◽  
Aromatic Side Chains

Aromatic side-chains (phenylalanine and tyrosine) of a protein flip by 180° around the Cβ-Cγ axis (χ2 dihedral of side-chain) producing two symmetry-equivalent states. The ring-flip dynamics act as an NMR probe to understand local conformational fluctuations. Ring-flips are categorized as slow (ms onwards) or fast (ns to near ms) based on timescales accessible to NMR experiments. In this study, we investigated the ability of the infrequent metadynamics approach to discriminate between slow and fast ring-flips for eight individual aromatic side-chains (F4, Y10, Y21, F22, Y23, F33, Y35, F45) of basic pancreatic trypsin inhibitor (BPTI). Well-tempered metadynamics simulations were performed to observe ring-flipping free energy surfaces for all eight aromatic residues. The results indicate that χ2 as a standalone collective variable (CV) is not sufficient to classify fast and slow ring-flips. Most of the residues needed χ1 (N−Cχα) as a complementary CV, indicating the importance of librational motions in ring-flips. Multiple pathways and mechanisms were observed for residues F4, Y10, and F22. Recrossing events are observed for residues F22 and F33, indicating a possible role of friction effects in the ring-flipping. The results demonstrate the successful application of the metadynamics based approach to estimate ring-flip rates of aromatic residues in BPTI and identify certain limitations of the approach.

Molecular aggregation in crystalline 1:1 complexes of hydrophobic D- and L-amino acids. I. The L-isoleucine series

1999 ◽  
Vol 55 (3) ◽  
pp. 424-431 ◽  
Author(s):  
Bjørn Dalhus ◽  
Carl Henrik Görbitz
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aminobutyric Acid ◽  
Side Chain ◽  
Side Chains ◽  
Amino Acid Side Chain ◽  
Molecular Aggregation ◽  
Plane Symmetry ◽  
Hydrogen Bond Pattern ◽  
Polar Parts

The amino acid L-isoleucine has been cocrystallized with seven selected D-amino acids including D-methionine [L-isoleucine–D-methionine (1/1), C6H13NO2.C5H11NO2S, amino-acid side chain R = —CH2—CH2—S—CH3] and a homologous series from D-alanine [L-isoleucine–D-alanine (1/1), C6H13NO2.C3H7NO2, R = —CH3] through D-α-aminobutyric acid [L-isoleucine–D-α-aminobutyric acid (1/1), C6H13NO2.C4H9NO2, R = —CH2—CH3] and D-norvaline [L-isoleucine–D-norvaline (1/1), C6H13NO2.C5H11NO2, R = —CH2—CH2—CH3] to D-norleucine [L-isoleucine–D-norleucine (1/1), C6H13NO2.C6H13NO2, R = —CH2—CH2—CH2—CH3] with linear side chains, and D-valine [L-isoleucine–D-valine (1/1), C6H13NO2.C5H11NO2, R = —CH—(CH3)2] and D-leucine [L-isoleucine–D-leucine (1/1), C6H13NO2.C6H13NO2, R = —CH2—CH—(CH3)2] with branched side chains. All the crystal structures are divided into distinct hydrophilic and hydrophobic layers. In the five complexes with amino acids with linear side chains the polar parts of the D- and L-amino acids are related by pseudo-glide-plane symmetry, and four of them have remarkably similar molecular arrangements. The D-valine and D-leucine complexes, on the other hand, are structurally quite different with the polar parts of the D- and L-amino acids related by pseudo-inversion. Differences in the hydrogen-bond pattern in the two molecular arrangements are discussed.

scholarly journals The Role of Arg13 in Protein Phosphatase M tPphA from Thermosynechococcus elongatus

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Jiyong Su ◽  
Karl Forchhammer
Keyword(s):  
Amino Acid ◽  
Protein Phosphatase ◽  
Arginine Residue ◽  
Side Chain ◽  
Wild Type ◽  
Catalytic Center ◽  
Nitrophenyl Phosphate ◽  
Reduced Activity ◽  
Amino Acid Variants

A highly conserved arginine residue is close to the catalytic center of PPM/PP2C-type protein phosphatases. Different crystal structures of PPM/PP2C homologues revealed that the guanidinium side chain of this arginine residue can adopt variable conformations and may bind ligands, suggesting an important role of this residue during catalysis. In this paper, we randomly mutated Arginine 13 of tPphA, a PPM/PP2C-type phosphatase from Thermosynechococcus elongatus, and obtained 18 different amino acid variants. The generated variants were tested towards p-nitrophenyl phosphate and various phosphopeptides. Towards p-nitrophenyl phosphate as substrate, twelve variants showed 3–7 times higher Km values than wild-type tPphA and four variants (R13D, R13F, R13L, and R13W) completely lost activity. Strikingly, these variants were still able to dephosphorylate phosphopeptides, although with strongly reduced activity. The specific inability of some Arg-13 variants to hydrolyze p-nitrophenyl phosphate highlights the importance of additional substrate interactions apart from the substrate phosphate for catalysis. The properties of the R13 variants indicate that this residue assists in substrate binding.

Amino acid side-chain populations in aqueous and saline solution: Bis-penicillamine enkephalin

Biopolymers ◽  
1992 ◽  
Vol 32 (12) ◽  
pp. 1623-1629 ◽  
Author(s):  
Paul E. Smith ◽  
B. Montgomery Pettitt
Keyword(s):  
Amino Acid ◽  
Saline Solution ◽  
Side Chain ◽  
Amino Acid Side Chain

Effect of charged amino acid side chain length on lateral cross-strand interactions between carboxylate- and guanidinium-containing residues in a β-hairpin

Amino Acids ◽  
2015 ◽  
Vol 47 (5) ◽  
pp. 885-898 ◽  
Author(s):  
Hsiou-Ting Kuo ◽  
Shing-Lung Liu ◽  
Wen-Chieh Chiu ◽  
Chun-Jen Fang ◽  
Hsien-Chen Chang ◽  
...  
Keyword(s):  
Amino Acid ◽  
Chain Length ◽  
Side Chain ◽  
Amino Acid Side Chain ◽  
Side Chain Length

The Influence of the Aromatic Amino Acid Side-Chains on the Sign of the Soret Cotton Effect in Chironomus Hemoglobin (CTT III)

1972 ◽  
Vol 27 (5) ◽  
pp. 530-532 ◽  
Author(s):  
Jörg Fleischhauer ◽  
Axel Wollmer
Keyword(s):  
Amino Acid ◽  
Aromatic Amino Acid ◽  
Cotton Effect ◽  
Side Chain ◽  
Side Chains ◽  
Aromatic Side Chain ◽  
Rotational Strength ◽  
Amino Acid Side Chains ◽  
Atomic Coordinates

The origin of the positive Soret Cotton effect of myoglobin was calculated by Hsu and WOODY on the basis of a mechanism taking into account the coupling of the Soret and aromatic side-chain π—π* transitions. HUBER and coworkers have worked out the atomic coordinates of a monomeric insect hemoglobin which exhibits a negative Soret Cotton effect.It seemed of some importance to examine the capability of this mechanism to explain the observed inversion of sign. The calculations resulted indeed in a negative total rotational strength (—0,2 DBM), the main contributions arising from phenylalanine residues.

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