The influence of the methionine residue on the dissociation mechanisms of photoionized methionine-enkephalin probed by VUV action spectroscopy

Abstract VUV action spectroscopy has recently gained interest for the study of peptides and proteins. However, numerous aspects of the fundamental processes involved in the photodissociation are yet to be understood. It can, for example, be expected that sulfur-containing amino-acid residues have a significant impact on the dissociation processes following photoionization because of their potential involvement in the transport of electron holes in proteins. In order to investigate the influence of the sulfur-containing methionine residue on the VUV photodissociation of a small peptide a VUV action spectroscopy study of gas-phase protonated methionine-enkephalin and leucine-enkephalin in the photon energy range of 6–35 eV was performed. The results show that upon non-ionizing photoexcitation, the fragmentation patterns of the two peptides are nearly identical, whereas significant differences were observed upon photoionization. The differences between the fragment yields and the identified specific dissociation channels for methionine-enkephalin could be explained by the high electron hole affinity of sulfur, which efficiently directs the radical to the methionine side chain. Additionally, for both peptides the presence of the intact photoionized precursor ions was confirmed by their isotopic patterns and the stability of these species could be evaluated. Graphic abstract

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Amino acid sequence of cyanogen bromide fragment CB5 of human hemopexin

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19890803 ◽

1989 ◽

Vol 54 (3) ◽

pp. 803-810 ◽

Cited By ~ 1

Author(s):

Ivan Kluh ◽

Ladislav Morávek ◽

Manfred Pavlík

Keyword(s):

Amino Acid ◽

Amino Acid Sequence ◽

Acid Hydrolysis ◽

Cyanogen Bromide ◽

Polypeptide Chain ◽

Amino Acid Residues ◽

Mild Acid Hydrolysis ◽

Methionine Residue ◽

Cyanogen Bromide Fragment ◽

Mild Acid

Cyanogen bromide fragment CB5 represents the region of the polypeptide chain of hemopexin between the fourth and fifth methionine residue (residues 232-352). It contains 120 amino acid residues in the following sequence: Arg-Cys-Ser-Pro-His-Leu-Val-Leu-Ser-Ala-Leu-Thr-Ser-Asp-Asn-His-Gly-Ala-Thr-Tyr-Ala-Phe-Ser-Gly-Thr-His-Tyr-Trp-Arg-Leu-Asp-Thr-Ser-Arg-Asp-Gly-Trp-His-Ser-Trp-Pro-Ile-Ala-His-Gln-Trp-Pro-Gln-Gly-Pro-Ser-Ala-Val-Asp-Ala-Ala-Phe-Ser-Trp-Glu-Glu-Lys-Leu-Tyr-Leu-Val-Gln-Gly-Thr-Gln-Val-Tyr-Val-Phe-Leu-Thr-Lys-Gly-Gly-Tyr-Thr-Leu-Val-Ser-Gly-Tyr-Pro-Lys-Arg-Leu-Glu-Lys-Glu-Val-Gly-Thr-Pro-His-Gly-Ile-Ile-Leu-Asp-Ser-Val-Asp-Ala-Ala-Phe-Ile-Cys-Pro-Gly-Ser-Ser-Arg-Leu-His-Ile-Met. The sequence was derived from the data on peptides prepared by cleavage of fragment CB5 by mild acid hydrolysis, by trypsin and chymotrypsin.

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Experimental and computational study on roles of WOx promoting strong metal support promoter interaction in Pt catalysts during glycerol hydrogenolysis

Scientific Reports ◽

10.1038/s41598-020-79764-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Tinnakorn Saelee ◽

Poonnapa Limsoonthakul ◽

Phakaorn Aphichoksiri ◽

Meena Rittiruam ◽

Mongkol Lerdpongsiripaisarn ◽

...

Keyword(s):

Density Of States ◽

Design Guidelines ◽

Total Density ◽

High Electron ◽

Metal Support Interaction ◽

Metal Support ◽

Glycerol Hydrogenolysis ◽

The Stability ◽

Total Density Of States ◽

Promoter Interaction

AbstractBiodiesel is of high interest due to increased demand for energy with the concern regarding more sustainable production processes. However, an inevitable by-product is glycerol. Hence, the conversion of this by-product to higher-value chemicals, especially 1,3-propanediol (1,3-PDO) via glycerol hydrogenolysis reaction, is one of the most effective pathways towards a profitable process. In general, this process is catalyzed by a highly active Pt-based catalyst supported on γ-Al2O3. However, its low 1,3-PDO selectivity and stability due to surface deactivation of such catalysts remained. This led to the surface modification by WOx to improve both the selectivity by means of the increased Brønsted acidity and the stability in terms of Pt leaching-resistance. Hence, we applied experimental and density functional theory (DFT)-based techniques to study the fundamentals of how WOx modified the catalytic performance in the Pt/γ-Al2O3 catalyst and provided design guidelines. The effects of WOx promoter on improved activity were due to the shifting of the total density of states towards the antibonding region evident by the total density of states (TDOS) profile. On the improved 1,3-PDO selectivity, the main reason was the increasing number of Brønsted acid sites due to the added WOx promoter. Interestingly, the stability improvement was due to the strong metal-support interaction (SMSI) that occurred in the catalyst, like typical high leaching-resistant catalysts. Also, the observed strong metal-support-promoter interaction (SMSPI) is an additional effect preventing leaching. The SMSPI stemmed from additional bonding between the WOx species and the Pt active site, which significantly strengthened Pt adsorption to support and a high electron transfer from both Pt and Al2O3 to WOx promoter. This suggested that the promising promoter for our reaction performed in the liquid phase would improve the stability if SMSI occurred, where the special case of the WOx promoter would even highly improve the stability through SMSPI. Nevertheless, various promoters that can promote SMSPI need investigations.

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Production, purification and characterization of thermomycolase, the extracellular serine protease of the thermophilic fungus Malbranchea pulchella var. sulfurea

Canadian Journal of Microbiology ◽

10.1139/m76-023 ◽

1976 ◽

Vol 22 (2) ◽

pp. 165-176 ◽

Cited By ~ 34

Author(s):

Poh Seng Ong ◽

G. Maurice Gaucher

Keyword(s):

Serine Protease ◽

Thermophilic Fungus ◽

Amino Acid Residues ◽

Submerged Cultures ◽

Ph Optimum ◽

Alkaline Serine Protease ◽

Associated Production ◽

Specificity Study ◽

Malbranchea Pulchella ◽

The Stability

The thermophilic fungus Malbranchea pulchella produces a single extracellular, alkaline, serine protease when grown at 45 °C, on 2% casein as sole carbon source. The growth-associated production of protease in submerged cultures was inhibited by addition of glucose, amino acids, or yeast extract. A simple four-step purification which yields homogeneous protease in 78% yield is described. The protease has an isoelectric point of 6.0, a pH optimum of 8.5, and is completely inhibited by serine protease inhibitors. A specificity study with small synthetic ester substrates indicated that the protease preferentially hydrolyzed bonds situated on the carboxyl side of aromatic or apolar amino acid residues which are not β-branched, positively charged or of the D configuration. Peptidase substrates and others such as N-acetyl-L-tyrosine-ethyl ester were not hydrolyzed. The protease was stable over a broad range of pH (6.5–9.5 at 30 °C, 20 h), and was particularly thermostable (t1/2 = 110 min at 73 °C, pH 7.4) in the presence of Ca2+ (10 mM). Macromolecules and Ca2+ also provide protection against the significant autolysis which occurs at pure protease concentrations greater than 0.01 mg/ml, as well as against surface denaturation which is enhanced by the presence of a silicone antifoam agent. Hence the stability of protease in submerged cultures is rationalized.

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Bioinspired organometallic chemistry

Pure and Applied Chemistry ◽

10.1351/pac200274010115 ◽

2002 ◽

Vol 74 (1) ◽

pp. 115-122 ◽

Cited By ~ 24

Author(s):

Lanny S. Liebeskind ◽

Jiri Srogl ◽

Cecile Savarin ◽

Concepcion Polanco

Keyword(s):

Organometallic Chemistry ◽

Refractory Metal ◽

Redox Active ◽

The Stability ◽

New Procedures ◽

Sulfur Containing ◽

Insight Into

Given the stability of the bond between a mercaptide ligand and various redox-active metals, it is of interest that Nature has evolved significant metalloenzymatic processes that involve key interactions of sulfur-containing functionalities with metals such as Ni, Co, Cu, and Fe. From a chemical perspective, it is striking that these metals can function as robust biocatalysts in vivo, even though they are often "poisoned" as catalysts in vitro through formation of refractory metal thiolates. Insight into the nature of this chemical discrepancy is under study in order to open new procedures in synthetic organic and organometallic chemistry.

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Radiolytic Modification of Sulfur-Containing Amino Acid Residues in Model Peptides: Fundamental Studies for Protein Footprinting

Analytical Chemistry ◽

10.1021/ac0484629 ◽

2005 ◽

Vol 77 (8) ◽

pp. 2437-2449 ◽

Cited By ~ 71

Author(s):

Guozhong Xu ◽

Mark R. Chance

Keyword(s):

Amino Acid ◽

Amino Acid Residues ◽

Protein Footprinting ◽

Sulfur Containing ◽

Model Peptides

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Study of Caspase 8 Inhibition for the Management of Alzheimer’s Disease: A Molecular Docking and Dynamics Simulation

Molecules ◽

10.3390/molecules25092071 ◽

2020 ◽

Vol 25 (9) ◽

pp. 2071

Author(s):

Syed Sayeed Ahmad ◽

Meetali Sinha ◽

Khurshid Ahmad ◽

Mohammad Khalid ◽

Inho Choi

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Molecular Docking ◽

Md Simulation ◽

Simulation Analysis ◽

Dynamics Simulation ◽

Caspase 8 ◽

Amino Acid Residues ◽

The Stability ◽

Molecular Docking And Dynamics

Alzheimer’s disease (AD) is the most common type of dementia and usually manifests as diminished episodic memory and cognitive functions. Caspases are crucial mediators of neuronal death in a number of neurodegenerative diseases, and caspase 8 is considered a major therapeutic target in the context of AD. In the present study, we performed a virtual screening of 200 natural compounds by molecular docking with respect to their abilities to bind with caspase 8. Among them, rutaecarpine was found to have the highest (negative) binding energy (−6.5 kcal/mol) and was further subjected to molecular dynamics (MD) simulation analysis. Caspase 8 was determined to interact with rutaecarpine through five amino acid residues, specifically Thr337, Lys353, Val354, Phe355, and Phe356, and two hydrogen bonds (ligand: H35-A: LYS353:O and A:PHE355: N-ligand: N5). Furthermore, a 50 ns MD simulation was conducted to optimize the interaction, to predict complex flexibility, and to investigate the stability of the caspase 8–rutaecarpine complex, which appeared to be quite stable. The obtained results propose that rutaecarpine could be a lead compound that bears remarkable anti-Alzheimer’s potential against caspase 8.

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Synthesis and Evaluation of Cyclic Acetals of Serine Hydroxylamine for Amide-Forming KAHA Ligations

Synthesis ◽

10.1055/s-0037-1611635 ◽

2019 ◽

Vol 51 (05) ◽

pp. 1273-1283 ◽

Cited By ~ 1

Author(s):

Simon Baldauf ◽

Jeffrey Bode

Keyword(s):

Amino Acid ◽

Amino Acid Residue ◽

Amino Acid Residues ◽

High Demand ◽

Cyclic Acetals ◽

Ligation Product ◽

Canonical Amino Acid ◽

The Stability ◽

Peptide Segments ◽

Derivatives Of

The α-ketoacid–hydroxylamine (KAHA) ligation allows the coupling of unprotected peptide segments. The most widely used variant employs a 5-membered cyclic hydroxylamine that forms a homoserine ester as the primary ligation product. While very effective, monomers that give canonical amino acid residues are in high demand. In order to preserve the stability and reactivity of cyclic hydroxylamines, but form a canonical amino acid residue upon ligation, we sought to prepare cyclic derivatives of serine hydroxylamine. An evaluation of several cyclization strategies led to cyclobutanone ketals as the leading structures. The preparation, stability, and amide-forming ligation of these serine-derived ketals are described.

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Mass Spectra of Some Carbamates and Related Ureas. II

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/51.2.347 ◽

1968 ◽

Vol 51 (2) ◽

pp. 347-365 ◽

Cited By ~ 1

Author(s):

W R Benson ◽

J N Damico

Keyword(s):

Spectral Data ◽

Relative Abundance ◽

Mass Spectra ◽

The Other ◽

Methyl Isocyanate ◽

Mass Spectral Data ◽

Mass Spectral ◽

Fragmentation Patterns ◽

Sulfur Containing

Abstract Mass spectral data for fourteen carbamates, live dithiocarbamates, one thiocarbamate, and eight phenylureas are given with some interpretations. Among the compounds examined were some sulfur-containing aliphatic oxime carbamates; these lost the sulfur moieties more easily than the methyl isocyanate moiety. In the aryl IV-methylcarbamate series, the CH3NCO moiety appears to be lost most easily, as it is in pyrolysis. When l-(2-chlorophenyI)-3- methylurea is fragmented, unexpectedly the [HNC0]+ ion is found in high relative abundance. However, the remaining ureas undergo fragmentation in a manner similar to their related carbamates. Although the two ethylene bisdithiocarbamates give essentially identical fragmentation patterns, the spectra of the other four thio- and dithiocarbamates show sufficient differences so that they may be distinguished from one another.

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