scholarly journals Initiating polyketide biosynthesis by on-line methyl esterification

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Pengwei Li ◽  
Meng Chen ◽  
Wei Tang ◽  
Zhengyan Guo ◽  
Yuwei Zhang ◽  
...  
Keyword(s):  
Acyl Carrier Protein ◽  
Wide Distribution ◽  
Ring System ◽  
Carboxyl Terminus ◽  
Side Chain ◽  
Side Reactions ◽  
Protecting Group ◽  
Polyketide Biosynthesis ◽  
Methyl Esterification ◽  
On Line

AbstractAurantinins (ARTs) are antibacterial polyketides featuring a unique 6/7/8/5-fused tetracyclic ring system and a triene side chain with a carboxyl terminus. Here we identify the art gene cluster and dissect ART’s C-methyl incorporation patterns to study its biosynthesis. During this process, an apparently redundant methyltransferase Art28 was characterized as a malonyl-acyl carrier protein O-methyltransferase, which represents an unusual on-line methyl esterification initiation strategy for polyketide biosynthesis. The methyl ester bond introduced by Art28 is kept until the last step of ART biosynthesis, in which it is hydrolyzed by Art9 to convert inactive ART 9B to active ART B. The cryptic reactions catalyzed by Art28 and Art9 represent a protecting group biosynthetic logic to render the ART carboxyl terminus inert to unwanted side reactions and to protect producing organisms from toxic ART intermediates. Further analyses revealed a wide distribution of this initiation strategy for polyketide biosynthesis in various bacteria.

scholarly journals Practical synthesis of 4-aryl- and 4-heteroarylazetidin-2-ones: applications in the synthesis of the Taxol® side chain

1994 ◽  
Vol 72 (10) ◽  
pp. 2131-2136 ◽  
Author(s):  
Allan W. Rey ◽  
Robert Droghini ◽  
James L. Douglas ◽  
Purushotham Vemishetti ◽  
Susan D. Boettger ◽  
...  
Keyword(s):  
Side Chain ◽  
Staudinger Reaction ◽  
Protecting Group ◽  
Practical Synthesis

A convenient, high-yielding procedure has been developed for the kilogram-scale synthesis of (±)-cis-3-acetoxy-4-phenylazetidin-2-one (3), a β-lactam that has been used in the semi-synthesis of Taxol®. The Staudinger reaction between hydrobenzamide (5) and acetoxyacetyl chloride in the presence of a base provided the α-benzylideneiminotoluene protected β-lactam 8. Without isolation of the intermediate β-lactam, the protecting group was removed under various reductive or hydrolytic conditions. The overall yields were about 80%. The synthesis of other (±)-cis-4-aryl- and 4-heteroarylazetidin-2-ones by this methodology has also been accomplished. These compounds are of value for the synthesis of 3′-Taxol® side-chain analogs and their preparation demonstrates the generality of this approach.

scholarly journals Sticky swinging arm dynamics: studies of an acyl carrier protein domain from the mycolactone polyketide synthase

2016 ◽  
Vol 473 (8) ◽  
pp. 1097-1110 ◽  
Author(s):  
Steven Vance ◽  
Olga Tkachenko ◽  
Ben Thomas ◽  
Mona Bassuni ◽  
Hui Hong ◽  
...  
Keyword(s):  
Polyketide Synthase ◽  
Acyl Carrier Protein ◽  
Protein Domain ◽  
Carrier Protein ◽  
Protein Surface ◽  
Prosthetic Group ◽  
Polyketide Biosynthesis ◽  
Covalently Linked

When covalently linked to an acyl carrier protein (ACP) and loaded with acyl substrate-mimics, some 4′-phosphopantetheine prosthetic group arms swing freely, whereas others stick to the protein surface, suggesting a possible mode of interaction with enzyme domains during polyketide biosynthesis.

scholarly journals The role of side chains in the interaction of new antitumor pyrimidoacridinetriones with DNA: molecular dynamics simulations.

2000 ◽  
Vol 47 (1) ◽  
pp. 47-57 ◽  
Author(s):  
J Mazerski ◽  
I Antonini ◽  
S Martelli
Keyword(s):  
Molecular Dynamics ◽  
Rational Design ◽  
Md Simulations ◽  
Ring System ◽  
Side Chain ◽  
Side Chains ◽  
Intercalation Complex ◽  
Highly Active ◽  
Simulation Techniques ◽  
Dynamics Simulations

Pyrimidoacridinetriones (PATs) are a new group of highly active antitumor compounds. It seems reasonable to assume that, like for some other acridine derivatives, intercalation into DNA is a necessary, however not a sufficient condition for antitumor activity of these compounds. Rational design of new compounds of this chemotype requires knowledge about the structure of the intercalation complex, as well as about interactions responsible for its stability. Computer simulation techniques such as molecular dynamics (MD) may provide valuable information about these problems. The results of MD simulations performed for three rationally selected PATs are presented in this paper. The compounds differ in the number and position of side chains. Each of the compounds was simulated in two systems: i) in water, and ii) in the intercalation complex with the dodecamer duplex d(GCGCGCGCGCGC)2. The orientation of the side chain in relation to the ring system is determined by the position of its attachment. Orientation of the ring system inside the intercalation cavity depends on the number and position of side chain(s). The conformations of the side chain(s) of all PATs studied in the intercalation complex were found to be very similar to those observed in water.

scholarly journals The intercalation of imidazoacridinones into DNA induces conformational changes in their side chain.

2000 ◽  
Vol 47 (1) ◽  
pp. 65-78 ◽  
Author(s):  
J Mazerski ◽  
K Muchewicz
Keyword(s):  
Conformational Changes ◽  
Ring System ◽  
Van Der Waals Interactions ◽  
Side Chain ◽  
Intercalation Complex ◽  
Highly Active ◽  
Antitumor Compounds ◽  
Chemical Constitution ◽  
Modelling Techniques ◽  
Dynamics Simulations

Imidazoacridinones (IAs) are a new group of highly active antitumor compounds. The intercalation of the IA molecule into DNA is the preliminary step in the mode of action of these compounds. There are no experimental data about the structure of an intercalation complex formed by imidazoacridinones. Therefore the design of new potentially better compounds of this group should employ the molecular modelling techniques. The results of molecular dynamics simulations performed for four IA analogues are presented. Each of the compounds was studied in two systems: i) in water, and ii) in the intercalation complex with dodecamer duplex d(GCGCGCGCGCGC)2. Significant differences in the conformation of the side chain in the two environments were observed for all studied IAs. These changes were induced by electrostatic as well as van der Waals interactions between the intercalator and DNA. Moreover, the results showed that the geometry of the intercalation complex depends on: i) the chemical constitution of the side chain, and ii) the substituent in position 8 of the ring system.

scholarly journals Crystal structure of ethyl (2S,2′R)-1′-benzyl-3-oxo-3H-dispiro[1-benzothiophene-2,3′-pyrrolidine-2′,11′′-indeno[1,2-b]quinoxaline]-4′-carboxylate

2015 ◽  
Vol 71 (3) ◽  
pp. o195-o196
Author(s):  
J. Govindaraj ◽  
R. Raja ◽  
M. Suresh ◽  
R. Raghunathan ◽  
A. SubbiahPandi
Keyword(s):  
Crystal Structure ◽  
Three Dimensional ◽  
Ring System ◽  
Side Chain ◽  
Dihedral Angles ◽  
Pyrrolidine Ring ◽  
Compound C ◽  
Dimensional Network ◽  
Centroid Distance ◽  
Quinoxaline Ring

In the title compound, C35H27N3O3S, the spiro-linked five-membered rings both adopt twisted conformations. The pyrrolidine ring makes dihedral angles of 80.5 (1) and 77.4 (9)° with the benzothiophene ring system and the quinoxaline ring system, respectively. The S atom and C=O unit of the benzothiophene ring system are disordered over two opposite orientations in a 0.768 (4):0.232 (4) ratio. The atoms of the ethyl side chain are disordered over two sets of sites in a 0.680 (16):0.320 (16) ratio. In the crystal, molecules are linked by C—H...O, C—H...N and π–π interactions [shortest centroid–centroid distance = 3.4145 (19) Å], resulting in a three-dimensional network.

Cyclopropyldimethylcarbinyl: A new acid-labile side-chain protecting group for asparagine and glutamine

Peptides 1994 ◽  
1995 ◽  
pp. 155-156
Author(s):  
L. A. Carpino ◽  
H. N. Shroff ◽  
H.-G. Chao ◽  
E. M. E. Mansour ◽  
F. Albericio
Keyword(s):  
Side Chain ◽  
Protecting Group ◽  
Acid Labile

Structural Basis of Acyl-Carrier Protein Interactions in Fatty Acid and Polyketide Biosynthesis

2020 ◽  
pp. 61-122 ◽  
Author(s):  
Jeffrey T. Mindrebo ◽  
Ashay Patel ◽  
Laëtitia E. Misson ◽  
Woojoo E. Kim ◽  
Tony D. Davis ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Protein Interactions ◽  
Acyl Carrier Protein ◽  
Structural Basis ◽  
Carrier Protein ◽  
Polyketide Biosynthesis

Basic principles

1999 ◽  
Author(s):  
Peter D. White ◽  
Weng C. Chan
Keyword(s):  
Amino Acid ◽  
Amino Acid Residue ◽  
Solid Phase ◽  
Analytical Techniques ◽  
Amide Bond ◽  
Peptide Chain ◽  
Side Reactions ◽  
Protecting Group ◽  
Solution Synthesis ◽  
Resin Loading

Construction of a peptide chain on an insoluble solid support has obvious benefits: separation of the intermediate peptides from soluble reagents and solvents can be effected simply by filtration and washing with consequent savings in time and labour over the corresponding operations in solution synthesis; many of the operations are amenable to automation; excess reagents can be employed to help to drive reactions to completion; and physical losses can be minimized as the peptide remains attached to the support throughout the synthesis. This approach does, however, have its attendant limitations. By-products arising from either incomplete reactions, side reactions, or impure reagents will accumulate on the resin during chain assembly and contaminate the final product. The effects on product purity of achieving less than 100% chemical efficiency in every step are illustrated dramatically in Table 1. This has serious implications with regard to product purification as the impurities generated will, by their nature, be very similar to the desired peptide and therefore extremely difficult to remove. Furthermore, the analytical techniques employed for following the progress of reactions in solution are generally not applicable, and recourse must generally be made to simple qualitative colour tests to detect the presence of residual amines on the solid phase. The principles of solid phase synthesis are illustrated in Figure 1. The C-terminal amino acid residue of the target peptide is attached to an insoluble support via its carboxyl group. Any functional groups in amino acid side chains must be masked with permanent protecting groups that are not affected by the reactions conditions employed during peptide chain assembly. The temporary protecting group masking the α-amino group during the initial resin loading is removed. An excess of the second amino acid is introduced, with the carboxy group of this amino acid being activated for amide bond formation through generation of an activated ester or by reaction with a coupling reagent. After coupling, excess reagents are removed by washing and the protecting group removed from the N-terminus of the dipeptide, prior to addition of the third amino acid residue.

scholarly journals GlucoSiFA and LactoSiFA: New Types of Carbohydrate-Tagged Silicon-Based Fluoride Acceptors for 18F-Positron Emission Tomography (PET)

Synthesis ◽  
2019 ◽  
Vol 51 (05) ◽  
pp. 1196-1206
Author(s):  
Anja Wiegand ◽  
Vera Wiese ◽  
Britta Glowacki ◽  
Ljuba Iovkova ◽  
Ralf Schirrmacher ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Emission Tomography ◽  
Side Chain ◽  
Protecting Group ◽  
Positron Emission ◽  
Silicon Based

GlucoSiFA derivatives bearing an azide or alkynyl side chain were obtained from peracetyl-d-glucose using as key step a tosylate substitution by a SiFA thiolate obtained from 4-(di-tert-butylfluorsilyl)benzenethiol. In analogy, two-fold SiFA-substituted maltose and lactose derivatives were synthesized via bistosylates. Introduction of an ­acetal-protecting group in β-d-azidolactose allowed the synthesis of a LactoSiFA derivative bearing only one SiFA moiety.

scholarly journals Offloading Role of a Discrete Thioesterase in Type II Polyketide Biosynthesis

mBio ◽  
2020 ◽  
Vol 11 (5) ◽  
Author(s):  
Kangmin Hua ◽  
Xiangyang Liu ◽  
Yuchun Zhao ◽  
Yaojie Gao ◽  
Lifeng Pan ◽  
...  
Keyword(s):  
Acyl Carrier Protein ◽  
Biological Activities ◽  
Condensation Reaction ◽  
Critical Role ◽  
Shake Flask Culture ◽  
Type Ii ◽  
Batch Mode ◽  
Polyketide Biosynthesis ◽  
Thioester Bond ◽  
Polyketide Chain

ABSTRACT Type II polyketides are a group of secondary metabolites with various biological activities. In nature, biosynthesis of type II polyketides involves multiple enzymatic steps whereby key enzymes, including ketoacyl-synthase (KSα), chain length factor (KSβ), and acyl carrier protein (ACP), are utilized to elongate the polyketide chain through a repetitive condensation reaction. During each condensation, the biosynthesis intermediates are covalently attached to KSα or ACP via a thioester bond and are then cleaved to release an elongated polyketide chain for successive postmodification. Despite its critical role in type II polyketide biosynthesis, the enzyme and its corresponding mechanism for type II polyketide chain release through thioester bond breakage have yet to be determined. Here, kinamycin was used as a model compound to investigate the chain release step of type II polyketide biosynthesis. Using a genetic knockout strategy, we confirmed that AlpS is required for the complete biosynthesis of kinamycins. Further in vitro biochemical assays revealed high hydrolytic activity of AlpS toward a thioester bond in an aromatic polyketide-ACP analog, suggesting its distinct role in offloading the polyketide chain from ACP during the kinamycin biosynthesis. Finally, we successfully utilized AlpS to enhance the heterologous production of dehydrorabelomycin in Escherichia coli by nearly 25-fold, which resulted in 0.50 g/liter dehydrorabelomycin in a simple batch-mode shake flask culture. Taken together, our results provide critical knowledge to gain an insightful understanding of the chain-releasing process during type II polyketide synthesis, which, in turn, lays a solid foundation for future new applications in type II polyketide bioproduction.

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