scholarly journals The Position 68(E11) Side Chain in Myoglobin Regulates Ligand Capture, Bond Formation with Heme Iron, and Internal Movement into the Xenon Cavities

2005 ◽  
Vol 280 (46) ◽  
pp. 38740-38755 ◽  
Author(s):  
David Dantsker ◽  
Camille Roche ◽  
Uri Samuni ◽  
George Blouin ◽  
John S. Olson ◽  
...  
Keyword(s):  
Bond Formation ◽  
Heme Iron ◽  
Side Chain

Peptide Modifications: Versatile Tools in Peptide and Natural Product Syntheses

Synlett ◽  
2019 ◽  
Vol 30 (11) ◽  
pp. 1289-1302 ◽  
Author(s):  
Phil Servatius ◽  
Lukas Junk ◽  
Uli Kazmaier
Keyword(s):  
Amino Acids ◽  
Natural Product ◽  
Bond Activation ◽  
Bond Formation ◽  
Side Chain ◽  
Peptide Backbone ◽  
Claisen Rearrangements ◽  
The Past ◽  
Allylic Alkylations ◽  
Peptide Modifications

Peptide modifications via C–C bond formation have emerged as valuable tools for the preparation and alteration of non-proteinogenic amino acids and the corresponding peptides. Modification of glycine subunits in peptides allows for the incorporation of unusual side chains, often in a highly stereoselective manner, orchestrated by the chiral peptide backbone. Moreover, modifications of peptides are not limited to the peptidic backbone. Many side-chain modifications, not only by variation of existing functional groups, but also by C–H functionalization, have been developed over the past decade. This account highlights the synthetic contributions made by our group and others to the field of peptide modifications and their application in natural product syntheses.1 Introduction2 Peptide Backbone Modifications via Peptide Enolates2.1 Chelate Enolate Claisen Rearrangements2.2 Allylic Alkylations2.3 Miscellaneous Modifications3 Side-Chain Modifications3.1 C–H Activation3.1.1 Functionalization via Csp3–H Bond Activation3.2.2 Functionalization via Csp2–H Bond Activation3.2 On Peptide Tryptophan Syntheses4 Conclusion

Critical Review of Biotransformational Studies on Steroids by Using Culture of Cunninghamella blakesleeana

2021 ◽  
Vol 18 ◽  
Author(s):  
Azizuddin ◽  
Muhammad Iqbal ◽  
Syed Ghulam Musharraf
Keyword(s):  
Double Bond ◽  
Critical Review ◽  
Structural Modification ◽  
Bond Formation ◽  
Environmentally Friendly ◽  
Side Chain ◽  
Synthetic Compounds ◽  
Efficient Approach ◽  
Cunninghamella Blakesleeana ◽  
Different Strains

: For several decades, biotransformational studies on steroidal compounds have gained a lot of attention because it is an efficient approach for the structural modification of complicated natural or synthetic compounds with high regio-, chemo- and stereoselectivity at environmentally friendly conditions. This review summarizes the use of different strains of Cunninghamella blakesleeana for the biotransformation of sixteen steroids 1-16 into a variety of transformed products. The transformed products may be important as a drug or precursor for the production of important pharmaceuticals. The types of reactions performed by C. blakesleeana include hydroxylation, epoxidation, reduction, demethylation, oxidation, glycosidation, double bond formation, side-chain degradation, isomerisation and opening of an isoxazol ring, which would be difficult to produce by traditional synthesis.

scholarly journals A Redox-controlled Molecular Switch Revealed by the Crystal Structure of a Bacterial Heme PAS Sensor

2004 ◽  
Vol 279 (19) ◽  
pp. 20186-20193 ◽  
Author(s):  
Hirofumi Kurokawa ◽  
Dong-Sun Lee ◽  
Miki Watanabe ◽  
Ikuko Sagami ◽  
Bunzo Mikami ◽  
...  
Keyword(s):  
Water Molecule ◽  
Protein Interactions ◽  
Iron Reduction ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Molecular Switch ◽  
Heme Iron ◽  
Side Chain ◽  
Dependent Manner ◽  
Pas Domain

PAS domains, which have been identified in over 1100 proteins from all three kingdoms of life, convert various input stimuli into signals that propagate to downstream components by modifying protein-protein interactions. One such protein is theEscherichia coliredox sensor,EcDOS, a phosphodiesterase that degrades cyclic adenosine monophosphate in a redox-dependent manner. Here we report the crystal structures of the heme PAS domain ofEcDOS in both inactive Fe3+and active Fe2+forms at 1.32 and 1.9 Å resolution, respectively. The protein folds into a characteristic PAS domain structure and forms a homodimer. In the Fe3+form, the heme iron is ligated to a His-77 side chain and a water molecule. Heme iron reduction is accompanied by heme-ligand switching from the water molecule to a side chain of Met-95 from the FG loop. Concomitantly, the flexible FG loop is significantly rigidified, along with a change in the hydrogen bonding pattern and rotation of subunits relative to each other. The present data led us to propose a novel redox-regulated molecular switch in which local heme-ligand switching may trigger a global “scissor-type” subunit movement that facilitates catalytic control.

scholarly journals Computational Study on O-O Bond Formation on a Mononuclear Non-Heme Iron Center

2020 ◽  
Vol 2020 (27) ◽  
pp. 2573-2581
Author(s):  
Chieh-Chih George Yeh ◽  
Gerald Hörner ◽  
Sam P. de Visser
Keyword(s):  
Computational Study ◽  
Bond Formation ◽  
Heme Iron ◽  
Non Heme Iron ◽  
Iron Center

scholarly journals Extension of the 5-alkynyluridine side chain via C–C-bond formation in modified organometallic nucleosides using the Nicholas reaction

2020 ◽  
Vol 16 ◽  
pp. 1-8 ◽  
Author(s):  
Renata Kaczmarek ◽  
Dariusz Korczyński ◽  
James R Green ◽  
Roman Dembinski
Keyword(s):  
Bond Formation ◽  
Side Chain ◽  
Nicholas Reaction ◽  
Propargyl Ether ◽  
Dicobalt Hexacarbonyl

Dicobalt hexacarbonyl nucleoside complexes of propargyl ether or esters of 5-substituted uridines react with diverse C-nucleophiles. Synthetic outcomes confirmed that the Nicholas reaction can be carried out in a nucleoside presence, leading to a divergent synthesis of novel metallo-nucleosides enriched with alkene, arene, arylketo, and heterocyclic functions, in the deoxy and ribo series.

scholarly journals Microbiological degradation of bile acids. Nitrogenous hexahydroindane derivatives formed from cholic acid by Streptomyces rubescens

1976 ◽  
Vol 160 (3) ◽  
pp. 745-755 ◽  
Author(s):  
S Hayakawa ◽  
S Hashimoto ◽  
T Onaka
Keyword(s):  
Cholic Acid ◽  
Bond Formation ◽  
Valeric Acid ◽  
Amide Bond ◽  
Side Chain ◽  
Mechanism Of Formation ◽  
Partial Synthesis ◽  
Degradative Pathway ◽  
Amide Bond Formation ◽  
New Compounds

The metabolism of cholic acid (I) by Streptomyces rubescens was investigated. This organism effected ring A cleavage, side-chain shortening and amide bond formation and gave the following metabolites: (4R)-4-[4α-(2-carboxyethyl)-3aα-hexahydro-7aβ-methyl-5-oxoindan-1 β-yl]valeric acid (IIa) and its mono-amide (valeramide) (IIb); and 2,3,4,6, 6aβ,7,8,9,9aα,9bβ-decahydro-6aβ-methyl-1H-cyclopenta[f]quinoline-3,7-dione(IIIe)and its homologues with the β-oriented side chains, valeric acid, valeramide, butanone and propionic acid, in the place of the oxo group at C-7, i.e.compounds (IIIa), (IIIb), (IIIc) and (IIId) respectively. All the nitrogenous metabolites were new compounds, and their structures were established by partial synthesis except for the metabolite (IIIc). The mechanism of formation of these metabolites is considered. A degradative pathway of cholic acid (I) into the metabolites is also tentatively proposed.

scholarly journals Crystal Structures of Cytochrome P450 105P1 from Streptomyces avermitilis: Conformational Flexibility and Histidine Ligation State

2008 ◽  
Vol 191 (4) ◽  
pp. 1211-1219 ◽  
Author(s):  
Lian-Hua Xu ◽  
Shinya Fushinobu ◽  
Haruo Ikeda ◽  
Takayoshi Wakagi ◽  
Hirofumi Shoun
Keyword(s):  
Crystal Structures ◽  
Biosynthetic Pathway ◽  
Heme Iron ◽  
Streptomyces Avermitilis ◽  
Side Chain ◽  
Wild Type ◽  
Loop Region ◽  
Polyene Macrolide Antibiotic ◽  
Spectroscopic Characteristics ◽  
Ligand Free

ABSTRACT The polyene macrolide antibiotic filipin is widely used as a probe for cholesterol in biological membranes. The filipin biosynthetic pathway of Streptomyces avermitilis contains two position-specific hydroxylases, C26-specific CYP105P1 and C1′-specific CYP105D6. In this study, we describe the three X-ray crystal structures of CYP105P1: the ligand-free wild-type (WT-free), 4-phenylimidazole-bound wild-type (WT-4PI), and ligand-free H72A mutant (H72A-free) forms. The BC loop region in the WT-free structure has a unique feature; the side chain of His72 within this region is ligated to the heme iron. On the other hand, this region is highly disordered and widely open in WT-4PI and H72A-free structures, respectively. Histidine ligation of wild-type CYP105P1 was not detectable in solution, and a type II spectral change was clearly observed when 4-phenylimidazole was titrated. The H72A mutant showed spectroscopic characteristics that were almost identical to those of the wild-type protein. In the H72A-free structure, there is a large pocket that is of the same size as the filipin molecule. The highly flexible feature of the BC loop region of CYP105P1 may be required to accept a large hydrophobic substrate.

scholarly journals P450 monooxygenase ComJ catalyses side chain phenolic cross-coupling during complestatin biosynthesis

RSC Advances ◽  
2017 ◽  
Vol 7 (56) ◽  
pp. 35376-35384 ◽  
Author(s):  
Aurelio Mollo ◽  
A. Nikolai von Krusenstiern ◽  
Joshua A. Bulos ◽  
Veronika Ulrich ◽  
Karin S. Åkerfeldt ◽  
...  
Keyword(s):  
High Efficiency ◽  
Bond Formation ◽  
Cross Coupling ◽  
Side Chain ◽  
P450 Monooxygenase ◽  
Peptide Substrates ◽  
Ether Bond ◽  
Biaryl Ether

P450 monooxygenase enzyme ComJ catalyzed biaryl ether bond formation with high efficiency and low stereoselectivity on selected complestatin-like peptide substrates.

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