2-Methyl-2,4-pentanediol (MPD) boosts as detergent-substitute the performance of ß-barrel hybrid catalyst for phenylacetylene polymerization

• Julia Kinzel,
• Daniel F. Sauer,
• Marco Bocola,
• Marcus Arlt,
• Tayebeh Mirzaei Garakani,
• Andreas Thiel,
• Klaus Beckerle,
• Tino Polen,
• Jun Okuda and
• Ulrich Schwaneberg

Beilstein J. Org. Chem. 2017, 13, 1498–1506, doi:10.3762/bjoc.13.148

• the β-barrel membrane channel protein FhuA WT co-crystallized with the detergent n-octyl-2-hydroxyethyl sulfoxide [24]. The N-terminal cork domain (residue 1-160) blocking the channel was removed. The amino acid exchanges of the hybrid catalyst model FhuA ΔCVFtev, namely cysteine at position 545

Characterization of non-heme iron aliphatic halogenase WelO5* from Hapalosiphon welwitschii IC-52-3: Identification of a minimal protein sequence motif that confers enzymatic chlorination specificity in the biosynthesis of welwitindolelinones

• Qin Zhu and
• Xinyu Liu

Beilstein J. Org. Chem. 2017, 13, 1168–1173, doi:10.3762/bjoc.13.115

• vector pQTEV. Heterologous expression in E. coli and purification by immobilized metal affinity chromatography (IMAC) gave the N-terminal hepta-His-tagged WelO5* in a comparable yield (20 mg/L) as for WelO5 [11]. With abundant WelO5* in hand, we proceeded on its in vitro characterization using the assay

Glycoscience@Synchrotron: Synchrotron radiation applied to structural glycoscience

• Serge Pérez and
• Daniele de Sanctis

Beilstein J. Org. Chem. 2017, 13, 1145–1167, doi:10.3762/bjoc.13.114

• characterization, the lectin, BC2L-C was shown to be composed of two distinct domains, each displaying unique specificities and biological activities. The protein is a super lectin that binds independently to fucosylated human histo-blood group epitopes and to mannose/heptose glycoconjugates. The N-terminal domain

Synthesis and enzymatic ketonization of the 5-(halo)-2-hydroxymuconates and 5-(halo)-2-hydroxy-2,4-pentadienoates

• Tyler M. M. Stack,
• William H. Johnson Jr. and
• Christian P. Whitman

Beilstein J. Org. Chem. 2017, 13, 1022–1031, doi:10.3762/bjoc.13.101

• -terminal methionine, the same enzyme with an N-formylmethionine, the intact enzyme with an N-terminal methionine, and the intact enzyme with an N-formylmethionine [25]. Synthesis of ethyl 2-fluorocrotonate and ethyl 2-bromocrotonate Ethyl 2-fluorocrotonate was synthesized following published procedures [18

• mass (6916 Da). In addition to this species (corresponding to the intact enzyme without the N-formylmethionine), there are five additional signals at 6475 Da, 6606 Da, 6634 Da, 7046 Da, and 7076 Da. These signals correspond to enzyme without the four C-terminal amino acids, the same enzyme with an N

Opportunities and challenges for the sustainable production of structurally complex diterpenoids in recombinant microbial systems

• Katarina Kemper,
• Max Hirte,
• Markus Reinbold,
• Monika Fuchs and
• Thomas Brück

Beilstein J. Org. Chem. 2017, 13, 845–854, doi:10.3762/bjoc.13.85

• example of these bifunctional enzymes was published by Chen and coworkers [60], who managed to crystalize catalytic domains of PaFS, a diterpene synthase from Phomopsis amygdali. The formation of GGPP is located in a C-terminal α-domain with very low sequence identity to the N-terminal Class I terpene

• engineered for functional and soluble expression in prokaryotic hosts like E. coli, Removal of the N-terminal and thereby the cell-wall-localization domain (indicated through scissors) is a standard procedure in engineering plant enzymes; 3: Further engineering steps are not mandatory but often entail site

Posttranslational isoprenylation of tryptophan in bacteria

• Masahiro Okada,
• Tomotoshi Sugita and
• Ikuro Abe

Beilstein J. Org. Chem. 2017, 13, 338–346, doi:10.3762/bjoc.13.37

• isoprenylated by ComQ is located at either the 3rd or 4th position from the C-terminal end, and the cleavage of the N-terminal residues leads to the production of the mature ComX pheromone with six to ten amino acid residues (Figure 5). In most ribosomally synthesized and posttranslationally modified peptides

• (RIPPs), a conserved recognition motif in the N-terminal leader region of the precursor peptide enables the enzymatic modification of the C-terminal core peptide, and then the leader amino acids are frequently cleaved [2]. However, there is no obvious sequence within the N-terminal region of the ComX

• amino acid residues, the N-terminal leucine residue and the modified tryptophan residue were the only conserved amino acids in the ComX variants. Therefore, a common consensus sequence for tryptophan isoprenylation does not seem to exist. In addition, the tryptophan residue modified with a geranyl group

Biochemical and structural characterisation of the second oxidative crosslinking step during the biosynthesis of the glycopeptide antibiotic A47934

• Veronika Ulrich,
• Clara Brieke and
• Max J. Cryle

Beilstein J. Org. Chem. 2016, 12, 2849–2864, doi:10.3762/bjoc.12.284

• -Hpg7 peptide as well as the mono- and bicyclic products based on P450-catalysed turnover have been analysed in earlier studies [13][16][17]. Prior to the activity assay the substrate was loaded onto the A47934 PCP-X di-domain construct exhibiting maltose binding protein as N-terminal fusion partner

• the low levels of StaH activity [12]. In order to analyse if this effect is maintained over the subsequent amino acid cyclisation reactions in A47934 biosynthesis, we tested StaF activity using the same constructs all exhibiting MBP as N-terminal fusion partner: a PCP-X construct from A47934

• conformation of the B–C loop, which exhibits a helical part in OxyAtei in contrast to StaF, and the position of the F and G helices, which are drawn down towards the centre of the protein in StaF closing the active site to a greater extent than observed for OxyAtei. In both the StaF structures, the N-terminal

Chemical probes for competitive profiling of the quorum sensing signal synthase PqsD of Pseudomonas aeruginosa

• Michaela Prothiwa,
• Dávid Szamosvári,
• Sandra Glasmacher and
• Thomas Böttcher

Beilstein J. Org. Chem. 2016, 12, 2784–2792, doi:10.3762/bjoc.12.277

• site specific labelling of PqsD Next, we were interested to investigate if any of the ABPP probes was capable of labelling PqsD. Therefore, we cloned the pqsD gene of Pseudomonas aeruginosa PAO1 into an expression vector encoding an N-terminal strep-tag. The protein was heterologously expressed in

Inhibition of peptide aggregation by means of enzymatic phosphorylation

• Kristin Folmert,
• Malgorzata Broncel,
• Hans v. Berlepsch,
• Christopher H. Ullrich,
• Mary-Ann Siegert and
• Beate Koksch

Beilstein J. Org. Chem. 2016, 12, 2462–2470, doi:10.3762/bjoc.12.240

• spectra were averaged over three scans (λ = 195–240 nm; 0.5 nm intervals; 2 mm bandwidth; 4 s response time, 100 nm min−1 scanning speed). Ellipticity was normalized to concentration (c [mol L−1]), number of residues (n = 27, including the N-terminal Abz group) and path length (l [cm]) by using Equation 1

Economical and scalable synthesis of 6-amino-2-cyanobenzothiazole

• Jacob R. Hauser,
• Hester A. Beard,
• Mary E. Bayana,
• Katherine E. Jolley,
• Stuart L. Warriner and
• Robin S. Bon

Beilstein J. Org. Chem. 2016, 12, 2019–2025, doi:10.3762/bjoc.12.189

• bioorthogonal reaction (k ≈ 10 M−1s−1) [9] for site-specific labelling or immobilisation of proteins 4, either at an N-terminal cysteine residue or at a 1,2-aminothiol group incorporated into a non-natural amino acid (Scheme 1) [10][11]. In addition, CBT derivatives have been used for the synthesis of polymeric

Biosynthesis of oxygen and nitrogen-containing heterocycles in polyketides

• Franziska Hemmerling and
• Frank Hahn

Beilstein J. Org. Chem. 2016, 12, 1512–1550, doi:10.3762/bjoc.12.148

Application of Cu(I)-catalyzed azide–alkyne cycloaddition for the design and synthesis of sequence specific probes targeting double-stranded DNA

• Svetlana V. Vasilyeva,
• Vyacheslav V. Filichev and
• Alexandre S. Boutorine

Beilstein J. Org. Chem. 2016, 12, 1348–1360, doi:10.3762/bjoc.12.128

• ) bearing either alkyne or azide groups were obtained via acylation of their N-terminal amine by the activated esters method in DMF in the presence of Hünig's base (see Supporting Information File 1 for experimental details). We have pursued several goals: 1) to synthesize a variety of modified MGBs with

• differ in the length and nature of the 3'-linker were synthesized and used for further conjugations [17][30]. Synthesis of polyamide-TFO conjugates by CuAAC reaction To establish conditions for the synthesis of TFO-MGB conjugates we used 5'-alkyne modified parallel TFOs (15–17) in combination with the N

• -terminal azide-modified MGBs 12 and 14 (see Figure 12, Figure 2B for the synthesis and Supporting Information File 1 for experimental details). Three combinations of the components were tried: TFO 15 and MGB 14 resulting in conjugate 23, TFO 16 (bifunctional) + two MGBs 12 (conjugate 24) and TFO 17 + MGB

Cyclisation mechanisms in the biosynthesis of ribosomally synthesised and post-translationally modified peptides

• Andrew W. Truman

Beilstein J. Org. Chem. 2016, 12, 1250–1268, doi:10.3762/bjoc.12.120

• RiPP pathways, which are often small and lacking in homology to one another [9]. There has therefore been a massive increase in the study of their biosynthesis in recent years. RiPPs usually originate from a larger precursor peptide that consists of an N-terminal leader sequence and a core peptide that

• contains the natural product precursor (Figure 1). The bottromycin precursor peptide represents a notable exception as it features an N-terminal core peptide and a C-terminal follower peptide [10][11][12][13]. The core peptide is post-translationally modified and cleaved from the leader peptide to yield a

• central kinase domain catalyses phosphorylation and an N-terminal lyase domain catalyses elimination [58]. Both class III and IV synthetases have C-terminal LanC-like cyclase domains, but class III enzymes lack the three conserved residues that bind zinc in the other classes [57], which is surprising

Assembly of synthetic Aβ miniamyloids on polyol templates

• Sebastian Nils Fischer and
• Armin Geyer

Beilstein J. Org. Chem. 2015, 11, 2646–2653, doi:10.3762/bjoc.11.284

• boronic ester to the valerolactam ring of Hot. Template 9 (2.30 mg, 4.40 µmol, 1.0 equiv) and peptide boronic acid 1 (7.35 mg, 8.80 µmol, 2.0 equiv) were dissolved in 0.7 mL DMSO-d6 in a NMR tube. A ratio of 9/C-terminal monoester/N-terminal monoester/13 (0.04:0.24:0.08:0.60) was observed in the presence

• concept of tailoring the length of the peptide boronic acid and a polyol template is shown in Figure 2. Results and Discussion The shortest known functional expansion of the amyloidogenic Aβ-peptide is the β-amyloid (17–21) Leu-Val-Phe-Phe-Ala [20] which was investigated as both a C-terminal 1 and as an N

• -terminal boronic acid 2. Peptide boronic acids of type 1 were synthesized on polymer-bound diethanolamine (PS-DEAM resin), according to the protocol in Supporting Information File 1, Figure S1 [21]. The electron-poor boronic acid 2, which was expected to be more reactive in boronic ester formation, was

Peptide–polymer ligands for a tandem WW-domain, an adaptive multivalent protein–protein interaction: lessons on the thermodynamic fitness of flexible ligands

• Katharina Koschek,
• Vedat Durmaz,
• Oxana Krylova,
• Marek Wieczorek,
• Shilpi Gupta,
• Martin Richter,
• Alexander Bujotzek,
• Christina Fischer,
• Rainer Haag,
• Christian Freund,
• Marcus Weber and
• Jörg Rademann

Beilstein J. Org. Chem. 2015, 11, 837–847, doi:10.3762/bjoc.11.93

• and Figure 4 show these theoretical results averaged over time as well as the three runs per polymer. Structural properties and descriptors. Dividing the Euklidean distance between two successive peptide attachment points by the number of bonds in between (i.e., between the N-terminal nitrogen atoms

Orthogonal dual-modification of proteins for the engineering of multivalent protein scaffolds

• Michaela Mühlberg,
• Michael G. Hoesl,
• Christian Kuehne,
• Jens Dernedde,
• Nediljko Budisa and
• Christian P. R. Hackenberger

Beilstein J. Org. Chem. 2015, 11, 784–791, doi:10.3762/bjoc.11.88

• . In the beginning of our studies, we expressed TTL recombinantly with an N-terminal His-tag and tobacco etch virus protease (TEV) cleavage site, leaving an N-terminal Ser after the cleavage. However, we were unable to cleave the tag. This is probably due to structural constraints at the TTL’s N

• -terminus leaving the TEV protease recognition site inaccessible for the protease (for more information on protein design see Supporting Information File 1). Therefore, the construct was altered to contain an unmodified N-terminus with Ser at position 2. The N-terminal Met is cleaved when followed by small

• amino acids like glycine, alanine or serine in the native process of N-terminal methionine excision (NME) [43]. This process exposes Ser2 at the N-terminus for subsequent N-terminal oxime ligation. It has to be noted that the incorporation of Aha, as known [42][44], can hamper NME and therefore delivers

Exploring monovalent and multivalent peptides for the inhibition of FBP21-tWW

• Lisa Maria Henning,
• Sumati Bhatia,
• Miriam Bertazzon,
• Michaela Marczynke,
• Oliver Seitz,
• Rudolf Volkmer,
• Rainer Haag and
• Christian Freund

Beilstein J. Org. Chem. 2015, 11, 701–706, doi:10.3762/bjoc.11.80

• aromatic residue N-terminal to the polyproline stretch could also be observed. To define an optimized single monovalent binder, we analyzed the affinities for a selected set of ligands from this panel of sequences with regard to FBP21’s WW domains by ITC under the same conditions as were used for the phage

Potential of acylated peptides to target the influenza A virus

• Daniel Lauster,
• Damian Pawolski,
• Julian Storm,
• Kai Ludwig,
• Rudolf Volkmer,
• Henry Memczak,
• Andreas Herrmann and
• Sumati Bhatia

Beilstein J. Org. Chem. 2015, 11, 589–595, doi:10.3762/bjoc.11.65

• . Results and Discussion Peptide synthesis and characterization Peptide synthesis was performed using a rink amide resin on an automatic synthesizer by the Fmoc/tert-butyl strategy [17][18]. The N-terminus of the N-terminal free resin bound peptide was acylated with stearic acid using O-(benzotriazol-1-yl

Gold(I)-catalysed synthesis of a furan analogue of thiamine pyrophosphate

• Amjid Iqbal,
• El-Habib Sahraoui and
• Finian J. Leeper

Beilstein J. Org. Chem. 2014, 10, 2580–2585, doi:10.3762/bjoc.10.270

• , involving gold(I)-catalysed cyclisation of an alkynyl alcohol to form the furan ring. The furan analogue of thiamine diphosphate (ThDP) was also made and tested for binding to and inhibition of pyruvate decarboxylase (PDC) from Zymomonas mobilis (overexpressed in E. coli with a N-terminal His-tag). It is a

• in Escherichia coli has been used in such studies but, in order to simplify the purification, in this study the gene was cloned into a pET28a vector, to give the enzyme an N-terminal His6-tag. This form of the protein was overexpressed in high yield in E. coli, and was easily purified on a Ni2+-NTA

Synthesis of novel conjugates of a saccharide, amino acids, nucleobase and the evaluation of their cell compatibility

• Dan Yuan,
• Xuewen Du,
• Junfeng Shi,
• Ning Zhou,
• Abdulgader Ahmed Baoum and
• Bing Xu

Beilstein J. Org. Chem. 2014, 10, 2406–2413, doi:10.3762/bjoc.10.250

• article reports the synthesis of novel conjugates containing three fundamental biological build blocks (saccharide, amino acids, and nucleobase) and their cell compatibility. The attachment of the saccharide to the N-terminal of the peptide or the nucleobase to the C-terminal of the peptide apparently

Synthesis and optical properties of pyrrolidinyl peptide nucleic acid carrying a clicked Nile red label

• Nattawut Yotapan,
• Chayan Charoenpakdee,
• Pawinee Wathanathavorn,
• Boonsong Ditmangklo,
• Hans-Achim Wagenknecht and
• Tirayut Vilaivan

Beilstein J. Org. Chem. 2014, 10, 2166–2174, doi:10.3762/bjoc.10.224

• completion of the synthesis, the N-terminal Fmoc group was removed and the free amino group was capped by acetylation. The acpcPNA on the solid support was spilt to 0.5 µmol portions for a further labeling experiment and treated with 1:1 dioxane/aqueous NH3 at 60 °C overnight to remove the nucleobase- and

Multivalent scaffolds induce galectin-3 aggregation into nanoparticles

• Candace K. Goodman,
• Mark L. Wolfenden,
• Pratima Nangia-Makker,
• Anna K. Michel,
• Avraham Raz and
• Mary J. Cloninger

Beilstein J. Org. Chem. 2014, 10, 1570–1577, doi:10.3762/bjoc.10.162

• domain without the N-terminal domain, did not result in aggregate formation (see Table S3, Supporting Information File 1). No aggregates were observed for dendrimers 2–5 in solution without addition of galectin-3, and no aggregates were observed for galectin-3 when glycodendrimers were absent from the

• solution. Taken together, these data support aggregate initiation as a response to specific carbohydrate binding interactions between lectin and glycodendrimer. They also reveal the significance of the N-terminal domain in formation of higher order aggregates. The presence of these aggregates was confirmed

• ). The measured diameter of the CRD domain from the crystal structure of galectin-3 is roughly 3 nm [34]. The N-terminal domain consists of slightly fewer amino acids but is unstructured. Assuming the unstructured portion contributes about the same size or slightly more to the diameter of the protein as

Pyrene-modified PNAs: Stacking interactions and selective excimer emission in PNA₂DNA triplexes

• Alex Manicardi,
• Lucia Guidi,
• Alice Ghidini and
• Roberto Corradini

Beilstein J. Org. Chem. 2014, 10, 1495–1503, doi:10.3762/bjoc.10.154

• increased compared to the unmodified PNA7 (20 °C vs 10 °C). The presence of a second pyrene unit at N-terminal position is more stabilizing than that at C-term (compare PNA5 and PNA2, 4). PNA4 is characterized by a broad melting curve, whereas for PNA6 a continuous drift was observed already for the PNA

• result in destabilization of the overall structure (see Tm of PNA1 in Table 1). However, for PNA2, the combined effect of two pyrene pairs properly positioned allows to increase both stability and selectivity of PNA compared to unmodified one. The N-terminal pyrene unit, in addition to the central one

Design, automated synthesis and immunological evaluation of NOD2-ligand–antigen conjugates

• Marian M. J. H. P. Willems,
• Gijs G. Zom,
• Nico Meeuwenoord,
• Ferry A. Ossendorp,
• Herman S. Overkleeft,
• Gijsbert A. van der Marel,
• Jeroen D. C. Codée and
• Dmitri V. Filippov

Beilstein J. Org. Chem. 2014, 10, 1445–1453, doi:10.3762/bjoc.10.148

• were selected as target molecules (Figure 1). In conjugate 2 the carboxylic acid function of the isoglutamine of the MDP is linked to the N-terminal amine of the antigenic peptide. In conjugate 3 the same acid function of the MDP connects to the C-terminal lysine of the antigenic peptide. The 3

• the peptide (4 vs 5) does not seem to affect the NOD2 stimulating activity significantly, although the N-terminal conjugate appears slightly more active than the C-terminal conjugated MDP. The ability of conjugates 2–5 to induce DC maturation was evaluated by measuring interleukin 12 (IL-12p40

• ineffective as compared to the NOD2 transfected HEK cells. Conclusion We have described the assembly of two MDP building blocks, suitable for automated solid-phase peptide synthesis, and their application in the construction of a set of four MDP-peptide conjugates. These conjugates comprised a C- or N

Carbohydrate PEGylation, an approach to improve pharmacological potency

• M. Eugenia Giorgi,
• Rosalía Agusti and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2014, 10, 1433–1444, doi:10.3762/bjoc.10.147

• interaction with the target site. GlycoPEGylation of proteins PEGylation of proteins is usually performed on the ε-amine group of lysine or on the unprotected α-amino of the N-terminal amino acid using N-hydroxysuccinimidyl (NHS) activated PEGs or aldehyde PEGs. This conjugation leads to heterogeneous