Chemoenzymatic synthesis of macrocyclic peptides and polyketides via thioesterase-catalyzed macrocyclization

• Senze Qiao,
• Zhongyu Cheng and
• Fuzhuo Li

Beilstein J. Org. Chem. 2024, 20, 721–733, doi:10.3762/bjoc.20.66

• of monomers in the final product intimately correlates with the order of modules in the assembly line (Scheme 1a). Beyond several additional domains, including ketoreductase (KR), dehydratase (DH), enoyl reductase (ER), and methyltransferase (MT) domains and epimerase (E) domains, which are

Shift of the reaction equilibrium at high pressure in the continuous synthesis of neuraminic acid

• Jannis A. Reich,
• Miriam Aßmann,
• Kristin Hölting,
• Paul Bubenheim,
• Jürgen Kuballa and
• Andreas Liese

Beilstein J. Org. Chem. 2022, 18, 567–579, doi:10.3762/bjoc.18.59

• reasons, the synthesis of N-acetylneuraminic acid (Neu5Ac) in a continuous fixed-bed reactor by an immobilized epimerase and aldolase was investigated in detail. The immobilized enzymes showed high stability, with half-life times > 173 days under storage conditions (6 °C in buffer) and reusability over 50

• particular, the circular reactor showed great potential to study reactions at high pressure while allowing for easy sampling. Additionally, an increase in affinity of pyruvate towards both tested enzymes was observed when high pressure was applied, as evidenced by a decrease of KI for the epimerase and KM

• for the aldolase from 108 to 42 mM and 91 to 37 mM, respectively. Keywords: aldolase; continuous fixed-bed reactor; enzyme; epimerase; GlcNAc; high pressure; immobilization; ManNAc; Neu5Ac; pyruvate; Introduction In times of a pandemic, the importance of substances to enhance the human immune system

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

A systems-based framework to computationally describe putative transcription factors and signaling pathways regulating glycan biosynthesis

• Theodore Groth,
• Rudiyanto Gunawan and
• Sriram Neelamegham

Beilstein J. Org. Chem. 2021, 17, 1712–1724, doi:10.3762/bjoc.17.119

• for the addition of GalNAc to glucuronic acid to increase chondroitin polymer length, CHST3, CHST11, and UST are involved in the sulfation of GalNAc and iduronic acid, and DSEL is the epimerase which converts glucuronic acid to iduronic acid in CS/DS chains. MECP2 disproportionately regulates heparan

• are critical for heparin sulfate function include the HS2/3/6ST sulfotransferases, the GlcA epimerase GLCE, and additional enzymes mediating N-sulfation (i.e., NDSTs). 11) Hyaluronan synthesis: This pathway consists of the three hyaluronan synthases, HAS1–3. 12) Glycophosphatidylinositol (GPI) anchor

Chemical structure of cichorinotoxin, a cyclic lipodepsipeptide that is produced by Pseudomonas cichorii and causes varnish spots on lettuce

• Hidekazu Komatsu,
• Takashi Shirakawa,
• Takeo Uchiyama and
• Tsutomu Hoshino

Beilstein J. Org. Chem. 2019, 15, 299–309, doi:10.3762/bjoc.15.27

• Val residues appeared with almost the same signal intensities in each of the 13C NMR spectra, which were obtained by the feedings of L- and D-Val (Figure S20B and S20C, Supporting Information File 1). This finding definitively demonstrated that an epimerase (racemase) is involved in the biosynthetic

• gene cluster. Differences in the 13C signal intensities were a little in the feeding experiments using L- or D-[1-13C]-Ala (see Figure S20D and S20E, Supporting Information File 1). These results indicated that an epimerase is involved in the biosynthetic gene cluster of this strain. Thus, we failed to

Polyketide stereocontrol: a study in chemical biology

• Kira J. Weissman

Beilstein J. Org. Chem. 2017, 13, 348–371, doi:10.3762/bjoc.13.39

• of KR2 for the unepimerized methyl configuration masks the KS1 epimerase activity. Subsequent work seemed to strengthen the idea that KS1 acts as an epimerase [48]. In this case (Figure 10b), the loading module-KS1 portion of DEBS 1 was grafted onto DEBS 3 (whose two modules 5 and 6 generate the

• epimerase. However, as it has now been clearly established that it is instead the KR domains that possess this activity, it must be assumed that the engineered synthase suffered a significant change in architecture which allowed the epimerization to happen spontaneously, perhaps by providing water with

• demonstrate the intrinsic epimerase activity of specific non-reducing KRs [87]. In this ‘tandem EIX’ format (Figure 14b), the ketoacyl substrate for the KR to be assayed is generated transiently from the appropriate reduced product by a second, validated non-epimerizing KR, at which point, the intrinsic

Recent highlights in biosynthesis research using stable isotopes

• Jan Rinkel and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2015, 11, 2493–2508, doi:10.3762/bjoc.11.271

• -[2H5,15N]threonine were fed to P. luminescens. The loss of one deuterium atom for an incorporated labeled amino acid (from Cα) directly supports an epimerase function within the corresponding NRPS module, and the incorporated building block can be assigned as D-configured. In this example, epimerization

Biosynthesis of rare hexoses using microorganisms and related enzymes

• Zijie Li,
• Yahui Gao,
• Hideki Nakanishi,
• Xiaodong Gao and
• Li Cai

Beilstein J. Org. Chem. 2013, 9, 2434–2445, doi:10.3762/bjoc.9.281

• an ezyme of the D-tagatose 3-epimerase family (DTEase, EC 5.1.3.-), which is a commercially attractive enzymatic reaction for D-psicose production (Scheme 2). To date, five DTEases from different organisms have been characterized and employed for the D-psicose synthesis. Izumori et al. firstly

• and 90 g of D-psicose were produced from 500 g of D-fructose as the starting material [30]. Kim et al. also characterized a putative DTEase from Agrobacterium tumefaciens [31] and due to its high substrate specificity towards D-psicose, this enzyme was renamed as D-psicose 3-epimerase (DPEase, EC

• -allose production. D-Allose can also be synthesized from inexpensive D-glucose as a starting material via a three-step bioconversion, sequentially catalyzed by D-xylose isomerase (EC 5.3.1.5), D-psicose 3-epimerase, and ribose-5-phosphate isomerase (Scheme 12). The overall conversion yield for the

An easily accessible sulfated saccharide mimetic inhibits in vitro human tumor cell adhesion and angiogenesis of vascular endothelial cells

• Grazia Marano,
• Claas Gronewold,
• Martin Frank,
• Anette Merling,
• Christian Kliem,
• Sandra Sauer,
• Manfred Wiessler,
• Eva Frei and
• Reinhard Schwartz-Albiez

Beilstein J. Org. Chem. 2012, 8, 787–803, doi:10.3762/bjoc.8.89

• siRNA inhibition of the fucosyltransferase FUT1 and GDP-4-keto-6-deoxymannose-epimerase/reductase (FX-protein) [19]. The FX-protein is required for de novo synthesis of GDP-fucose from GDP-mannose [46], whereas FUT 1 catalyzes the α2 fucosylation of blood group H type 1 and Lewisy oligosaccharides. The

Chemo-enzymatic modification of poly-N-acetyllactosamine (LacNAc) oligomers and N,N-diacetyllactosamine (LacDiNAc) based on galactose oxidase treatment

• Christiane E. Kupper,
• Ruben R. Rosencrantz,
• Birgit Henßen,
• Helena Pelantová,
• Stephan Thönes,
• Anna Drozdová,
• Vladimir Křen and
• Lothar Elling

Beilstein J. Org. Chem. 2012, 8, 712–725, doi:10.3762/bjoc.8.80

• -glycosyltransferases, human β1,4-galactosyltransferase-1 (β4Gal-transferase) [68] and the β1,3-N-acetylglucosaminyltransferase from Helicobacter pylori (β3GlcNAc-transferase) [69], as well as UDP-Glc/GlcNAc 4'-epimerase from Campylobacter jejuni [70] were recombinantly produced in E. coli, purified and combined in a

• mM MnCl2, 1 mM MgCl2, 2 U/mL alkaline phosphatase approx. 5 mU/mL β4Gal-transferase, approx. 25 mU/mL β3GlcNAc-transferase and approx. 3.5 U/mL UDP-Glc/GlcNAc 4'-epimerase for 48 h to 72 h. In order to yield even- or odd-numbered poly-LacNAc glycans, the reactions were stopped by ultrafiltration

• (molecular weight cut off at 30 kDa) and subsequently terminated by the addition of β4Gal-transferase, UDP-Glc/GlcNAc 4'-epimerase and UDP-Glc, or β3GlcNAc-transferase and UDP-GlcNAc, as described above, and incubation for 24 h. The isolation of single, defined poly-LacNAc–linker–t-Boc-glycans (1a–d and

Natural product biosyntheses in cyanobacteria: A treasure trove of unique enzymes

• Jan-Christoph Kehr,
• Douglas Gatte Picchi and
• Elke Dittmann

Beilstein J. Org. Chem. 2011, 7, 1622–1635, doi:10.3762/bjoc.7.191

• domain; PCP: Peptidyl carrier protein; MT: Methyltransferase; E: Epimerase; AT: Acyltransferase; ACP: Acyl carrier protein; KS: Ketosynthase; KR: Ketoreductase; DH: Dehydratase; ER: Enoyl reductase; TE: Thioesterase. Structures of NRPS and PKS products in freshwater cyanobacteria. A) Synthesis of the

Coupled chemo(enzymatic) reactions in continuous flow

• Ruslan Yuryev,
• Simon Strompen and
• Andreas Liese

Beilstein J. Org. Chem. 2011, 7, 1449–1467, doi:10.3762/bjoc.7.169

• conversions in the range of 95–98%. The continuous enzymatic synthesis of N-acetylneuraminic acid (17) from N-acetylglucosamine (GlcNAc, 14) in an enzyme membrane reactor employing two enzymes was developed by Kragl and coworkers [27]. In their coupled-reaction system the first enzyme GlcNAc 2-epimerase

• -acetylneuraminic acid (17) in a continuously operated enzyme membrane reactor. E1: Epimerase; E2: Aldolase [27]. Chemo-enzymatic epoxidation of 1-methylcyclohexene (18) in a packed-bed reactor (PBR) containing Novozym 435 (E) [28]. Continuous production of (R)-1-phenylethyl propionate (24) by dynamic kinetic

• : Transketolase; E10: Epimerase; E11: Phosphoribulokinase [41]. Continuous hydrolysis of 4-cyanopyridine (59) to isonicotinic acid (61) in a cascade of two packed-bed reactors. E1: Nitrilase; E2: Amidase [42]. Continuous fermentative production of ethanol (64) from hardwood lignocellulose (62) in a stirred-tank

Bioorthogonal metabolic glycoengineering of human larynx carcinoma (HEp-2) cells targeting sialic acid

• Arne Homann,
• Riaz-ul Qamar,
• Sevnur Serim,
• Petra Dersch and
• Jürgen Seibel

Beilstein J. Org. Chem. 2010, 6, No. 24, doi:10.3762/bjoc.6.24

• ][10]. The bifunctional enzyme UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE) is the key enzyme in sialic acid biosynthesis. The inhibitory effect of the sialic acid concentration towards the UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE) by allosteric

• effects is known [11]. Recently, the regulation of UDP-GlcNAc 2-epimerase/ManNAc kinase expression on the transcriptional level by DNA methylation was demonstrated [12] and a genetic feedback regulation for this process was proposed (Scheme 3) [13]. Ac4GlcNAz 16 or Neu5Hex 3, respectively, were incubated

• and the genetic control of Neu5Ac 1 synthesis by feedback inhibition. The accumulation of Neu5Hex 3 is proposed by incubation of 3 with the target cell line as the synthesis of Neu5Ac 1 is down-regulated [11][13]. UDP: uridine diphosphate; GNE: UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine