Dissociation States of Collagen Functional Groups and their Effects on the Priming Efficacy of HEMA Bonded to Collagen

2003 ◽  
Vol 82 (4) ◽  
pp. 257-261 ◽  
Author(s):  
N. Nishiyama ◽  
K. Suzuki ◽  
A. Nagatsuka ◽  
I. Yokota ◽  
K. Nemoto
Keyword(s):  
Amino Acid ◽  
Carboxylic Acid ◽  
Bond Strength ◽  
Functional Groups ◽  
Functional Group ◽  
Side Chain ◽  
Amino Acid Residues ◽  
Bonding Agents

Applying 2-hydroxyethylmethacrylate (HEMA) solution to etched dentin enhances the bonding of resin to dentin. However, the principal adhesion mechanisms have not yet been identified. In this study, we examined the dissociation states of the collagen functional groups of the side-chain amino acid residues and their effects on the bond strength of resin to etched dentin primed by the HEMA solution. The bond strength was strongly dependent upon the dissociation state of the collagen functional groups. Inhibiting the dissociation of the carboxylic acid or the amine of a collagen functional group resulted in increased bond strength of resin to collagen. By understanding the significance of inhibiting the dissociation state, we can better design and develop more effective and efficient primer and bonding agents.

Schistosomal Sulfotransferase Interaction with Oxamniquine Involves Hybrid Mechanism of Induced-fit and Conformational Selection

2020 ◽  
Vol 16 (4) ◽  
pp. 451-459 ◽  
Author(s):  
Fortunatus C. Ezebuo ◽  
Ikemefuna C. Uzochukwu
Keyword(s):  
Molecular Dynamics ◽  
Amino Acid ◽  
Binding Energy ◽  
Binding Site ◽  
Conformational Dynamics ◽  
Side Chain ◽  
Amino Acid Residues ◽  
Conformational Selection ◽  
Hybrid Mechanism ◽  
Dynamics Simulations

Background: Sulfotransferase family comprises key enzymes involved in drug metabolism. Oxamniquine is a pro-drug converted into its active form by schistosomal sulfotransferase. The conformational dynamics of side-chain amino acid residues at the binding site of schistosomal sulfotransferase towards activation of oxamniquine has not received attention. Objective: The study investigated the conformational dynamics of binding site residues in free and oxamniquine bound schistosomal sulfotransferase systems and their contribution to the mechanism of oxamniquine activation by schistosomal sulfotransferase using molecular dynamics simulations and binding energy calculations. Methods: Schistosomal sulfotransferase was obtained from Protein Data Bank and both the free and oxamniquine bound forms were subjected to molecular dynamics simulations using GROMACS-4.5.5 after modeling it’s missing amino acid residues with SWISS-MODEL. Amino acid residues at its binding site for oxamniquine was determined and used for Principal Component Analysis and calculations of side-chain dihedrals. In addition, binding energy of the oxamniquine bound system was calculated using g_MMPBSA. Results: The results showed that binding site amino acid residues in free and oxamniquine bound sulfotransferase sampled different conformational space involving several rotameric states. Importantly, Phe45, Ile145 and Leu241 generated newly induced conformations, whereas Phe41 exhibited shift in equilibrium of its conformational distribution. In addition, the result showed binding energy of -130.091 ± 8.800 KJ/mol and Phe45 contributed -9.8576 KJ/mol. Conclusion: The results showed that schistosomal sulfotransferase binds oxamniquine by relying on hybrid mechanism of induced fit and conformational selection models. The findings offer new insight into sulfotransferase engineering and design of new drugs that target sulfotransferase.

Synthesis and conformation of sequential basic polypeptides with branched and linear side chains

1985 ◽  
Vol 50 (12) ◽  
pp. 2925-2936 ◽  
Author(s):  
Štěpánka Štokrová ◽  
Jan Pospíšek ◽  
Jaroslav Šponar ◽  
Karel Bláha
Keyword(s):  
Amino Acid ◽  
Salt Concentration ◽  
Salt Solution ◽  
Theoretical Work ◽  
Side Chain ◽  
Amino Acid Residues ◽  
Cd Spectra ◽  
Low Salt ◽  
Conformational Freedom ◽  
Basic Polypeptides

Polypeptides (Lys-X-Ala)n and (Lys-X-Gly)n in which X represents residues of isoleucine and norleucine, respectively, and polypeptide (Tle-Lys-Ala)n, were synthesized via polymerization of 1-hydroxysuccinimidyl esters of the appropriate tripeptides to complete previously studied series. Circular dichroism (CD) spectra of the respective polymers were measured as a function of pH and salt concentration of the medium. The results were correlated with those obtained previously with the same series containing different amino acid residues at the X-position. The helix forming ability of the polypeptides (Lys-X-Ala)n with linear X side chain was found to be independent of the length. In the series (Lys-X-Gly)n the unordered conformation was the most probable one except (Lys-Ile-Gly)n. This polymer assumed the β conformation even in low salt solution at neutral pH. An agreement with some theoretical work concerned with the restriction of conformational freedom of amino acid residue branching at Cβ atom with our experimental results is evident.

Analogues of the cholecystokinin octapeptide modified in the central part of the molecule

1991 ◽  
Vol 56 (9) ◽  
pp. 1963-1970 ◽  
Author(s):  
Jan Hlaváček ◽  
Václav Čeřovský ◽  
Jana Pírková ◽  
Pavel Majer ◽  
Lenka Maletínská ◽  
...  
Keyword(s):  
Amino Acid ◽  
Biological Activities ◽  
Point Of View ◽  
Biologically Active ◽  
Side Chain ◽  
Amino Acid Residues ◽  
Cholecystokinin Octapeptide ◽  
Biological Tests ◽  
Biological Potency ◽  
Biologically Active Conformation

In a series of analogues of the cholecystokinin octapeptide (CCK-8) the amino acid residues were gradually modified by substituting Gly by Pro in position 4, Trp by His in position 5, Met by Cle in position 6, or the Gly residue was inserted between Tyr and Met in positions 2 and 3 of the peptide chain, and in the case of the cholecystokinin heptapeptide (CCK-7) the Met residues were substituted by Nle or Aib. These peptides were investigated from the point of view of their biological potency in the peripheral and central region. From the results of the biological tests it follows that the modifications carried out in these analogues and in their Nα-Boc derivatives mean a suppression of the investigated biological activities by 2-3 orders of magnitude (at a maximum dose of the tested substance of 2 . 10-2 mg per animal).This means that a disturbance of the assumed biologically active conformation of CCK-8, connected with a considerable decrease of the biological potency of the molecule, takes place not only after introduction of the side chain into its centre (substitution of Gly4), but also after the modification of the side chains of the amino acids or by extension of the backbone in further positions around this central amino acid.

scholarly journals Effect of roasting temperature on lipid and protein oxidation and amino acid residue side chain modification of beef patties

RSC Advances ◽  
2021 ◽  
Vol 11 (35) ◽  
pp. 21629-21641
Author(s):  
Chao Xia ◽  
Pingping Wen ◽  
Yaming Yuan ◽  
Xiaofan Yu ◽  
Yijing Chen ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Residue ◽  
Protein Oxidation ◽  
Relative Number ◽  
Side Chain ◽  
Amino Acid Residues ◽  
Beef Patties ◽  
Lipid And Protein Oxidation ◽  
Roasting Temperature

The relative number of peptides modified by the amino acid residues of actin from raw beef patties and those cooked at different roasting temperatures.

scholarly journals Development of Antimicrobial Stapled Peptides Based on Magainin 2 Sequence

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 444
Author(s):  
Motoharu Hirano ◽  
Chihiro Saito ◽  
Hidetomo Yokoo ◽  
Chihiro Goto ◽  
Ryuji Kawano ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Amino Acid ◽  
Hemolytic Activity ◽  
Helical Structure ◽  
Antimicrobial Activities ◽  
Side Chain ◽  
Membrane Disruption ◽  
Amino Acid Residues ◽  
Electrophysiological Measurements ◽  
Cell Membrane Disruption

Magainin 2 (Mag2), which was isolated from the skin of the African clawed frog, is a representative antimicrobial peptide (AMP) that exerts antimicrobial activity via microbial membrane disruption. It has been reported that the helicity and amphipathicity of Mag2 play important roles in its antimicrobial activity. We investigated and recently reported that 17 amino acid residues of Mag2 are required for its antimicrobial activity, and accordingly developed antimicrobial foldamers containing α,α-disubstituted amino acid residues. In this study, we further designed and synthesized a set of Mag2 derivatives bearing the hydrocarbon stapling side chain for helix stabilization. The preferred secondary structures, antimicrobial activities, and cell-membrane disruption activities of the synthesized peptides were evaluated. Our analyses revealed that hydrocarbon stapling strongly stabilized the helical structure of the peptides and enhanced their antimicrobial activity. Moreover, peptide 2 stapling between the first and fifth position from the N-terminus showed higher antimicrobial activity than that of Mag2 against both gram-positive and gram-negative bacteria without exerting significant hemolytic activity. To investigate the modes of action of tested peptides 2 and 8 in antimicrobial and hemolytic activity, electrophysiological measurements were performed.

scholarly journals Glycine in Water Favors the Polyproline II State

Biomolecules ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1121 ◽  
Author(s):  
Brian Andrews ◽  
Shuting Zhang ◽  
Reinhard Schweitzer-Stenner ◽  
Brigita Urbanc
Keyword(s):  
Amino Acid ◽  
Spectroscopic Data ◽  
Heavy Atom ◽  
Conformational Space ◽  
Side Chain ◽  
Amino Acid Residues ◽  
Glycine Residue ◽  
Polyproline Ii ◽  
Conformational Preferences ◽  
Central Residue

Conformational preferences of amino acid residues in water are determined by the backbone and side-chain properties. Alanine is known for its high polyproline II (pPII) propensity. The question of relative contributions of the backbone and side chain to the conformational preferences of alanine and other amino acid residues in water is not fully resolved. Because glycine lacks a heavy-atom side chain, glycine-based peptides can be used to examine to which extent the backbone properties affect the conformational space. Here, we use published spectroscopic data for the central glycine residue of cationic triglycine in water to demonstrate that its conformational space is dominated by the pPII state. We assess three commonly used molecular dynamics (MD) force fields with respect to their ability to capture the conformational preferences of the central glycine residue in triglycine. We show that pPII is the mesostate that enables the functional backbone groups of the central residue to form the most hydrogen bonds with water. Our results indicate that the pPII propensity of the central glycine in GGG is comparable to that of alanine in GAG, implying that the water-backbone hydrogen bonding is responsible for the high pPII content of these residues.

Efficient and Practical Procedure for the Esterification of the Free α-Carboxylic Acid of Amino Acid Residues with β-(Trimethylsilyl)ethoxymethyl Chloride and Triisopropylsilyl Chloride

Synthesis ◽  
2014 ◽  
Vol 46 (22) ◽  
pp. 3075-3084 ◽  
Author(s):  
Renata de Figueiredo ◽  
Jean-Marc Campagne ◽  
Jean-Simon Suppo ◽  
Danilo de Sant’Ana ◽  
Luiz Dias
Keyword(s):  
Amino Acid ◽  
Carboxylic Acid ◽  
Amino Acid Residues ◽  
Practical Procedure

scholarly journals Differentiating Amino Acid Residues and Side Chain Orientations in Peptides Using Scanning Tunneling Microscopy

2013 ◽  
Vol 135 (49) ◽  
pp. 18528-18535 ◽  
Author(s):  
Shelley A. Claridge ◽  
John C. Thomas ◽  
Miles A. Silverman ◽  
Jeffrey J. Schwartz ◽  
Yanlian Yang ◽  
...  
Keyword(s):  
Amino Acid ◽  
Scanning Tunneling Microscopy ◽  
Side Chain ◽  
Scanning Tunneling ◽  
Amino Acid Residues ◽  
Tunneling Microscopy

Diversifying Polyhydroxyalkanoates – End-Group and Side-Chain Functionality

2017 ◽  
Vol 14 (6) ◽  
pp. 757-767 ◽  
Author(s):  
Michal Michalak ◽  
Iwona Kwiecien ◽  
Michal Kwiecien ◽  
Grazyna Adamus ◽  
Karin Odelius ◽  
...  
Keyword(s):  
Functional Groups ◽  
Polymer Chain ◽  
Ring Opening ◽  
Functional Group ◽  
Side Chain ◽  
Natural Origin ◽  
Polymer Formation ◽  
End Groups ◽  
Group Diversity ◽  
End Group

Background: Polyhydroxyalkanoates (PHAs) are a natural origin biodegradable polyesters consisted of various 3- and 4-hydroxyacid derived repeating units produced by microorganisms as energy storage. PHAs have been intensively studied due to their biodegradability and biocompatibility enabling their use both in packaging and agriculture as well as in medicine and pharmacy. PHAs obtained via biotechnological routes can possess various functional groups in their side chains. However, the diversity in their functionality is limited due to issues of conservation of functional groups during the polymer formation. Objective: The review focuses on recent progress in the area of synthesis of PHAs functionalized with various reactive as well as bioactive end and side groups. Conclusion: A potent route to resolve the problem of functional group diversity in natural origin PHAs involves post-polymerization modification, where the desired side groups can be created. On the contrary, synthetically produced PHA analogs obtained directly via ring-opening polymerization of β-lactones offer various functionalities at different position throughout the polymer chain. The desired α- and ω-end groups can be introduced into the polymer chain using specific polymerization, initiation or termination strategies, respectively. The preferred side chain functionality is obtained by choosing the appropriate β-lactone monomers bearing respective functional groups. All functional groups may also be subjected to additional chemical modification. The degradation of PHA as a method for producing functional polymers as well as their possible further applications are also discussed.

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