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

• -Boc (2) was synthesised as described previously with some modifications [11]. To increase enzyme stability after purification, the buffer was exchanged to storage buffer (100 mM MOPS, 25 mM KCl, pH 6.8) and 20% glycerol was added to reduce protein precipitation. To reach an improved conversion of the

• change of the fermentation temperature to 25 °C was followed by the addition of isopropyl β-D-thiogalactopyranoside (IPTG) yielding a concentration of 1 mM. Additionally a feed (approx. 0.1 mL/min) of 50% (v/v) glycerol in water was applied. Cultivation was terminated 2 h after IPTG addition, yielding 60

An easy α-glycosylation methodology for the synthesis and stereochemistry of mycoplasma α-glycolipid antigens

• Yoshihiro Nishida,
• Yuko Shingu,
• Yuan Mengfei,
• Kazuo Fukuda,
• Hirofumi Dohi,
• Sachie Matsuda and
• Kazuhiro Matsuda

Beilstein J. Org. Chem. 2012, 8, 629–639, doi:10.3762/bjoc.8.70

• one-pot α-glycosylation method was effectively applied. The synthetic GGPL-I isomers were characterized with 1H NMR spectroscopy to determine the equilibrium among the three conformers (gg, gt, tg) at the acyclic glycerol moiety. The natural GGPL-I isomer was found to prefer gt (54%) and gg (39

• and characterized by other groups [11][12][13][14]. Absolute chemical structures of GGPL-I [15] and GGPL–III [16] have already been established by chemical syntheses of stereoisomers; these α-glycolipids have a common chemical backbone of 3-O-(α-D-glucopyranosyl)-sn-glycerol carrying phosphocholine at

• the sugar primary (6-OH) position. The fatty acids at the glycerol moiety are saturated, namely palmitic acid (C16:0) and stearic acid (C18:0). GGPL-I has a structural feature analogous to 1,2-di-O-palmitoyl phosphatidylcholine (DPPC) as a ubiquitous cell membrane phospholipid. Apparently, GGPLs are

Mutational analysis of a phenazine biosynthetic gene cluster in Streptomyces anulatus 9663

• Orwah Saleh,
• Katrin Flinspach,
• Lucia Westrich,
• Andreas Kulik,
• Bertolt Gust,
• Hans-Peter Fiedler and
• Lutz Heide

Beilstein J. Org. Chem. 2012, 8, 501–513, doi:10.3762/bjoc.8.57

• selection of recombinant strains. Chemicals Kanamycin and carbenicillin were purchased from Genaxxon BioSciences GmbH (Biberach, Germany) and phenazine 1-carboxylic acid was from InFormatik. IPTG, Tris, NaCl, glycerol, dithiothreitol, MgCl2, formic acid, sodium dodecyl sulfate, polyacrylamide, and EDTA were

• a further 10 h at 20 °C and harvested. Then, 30 mL of lysis buffer (50 mM Tris-HCl, pH 8.0, 1 M NaCl, 10% glycerol, 10 mM β-mercaptoethanol, 20 mM imidazole, 0.5 mg·mL−1 lysozyme, 0.5 mM phenylmethylsulfonyl fluoride) was added to the pellet (40 g). After being stirred at 4 °C for 30 min, cells were

• Tris-HCl, pH 8.0, 1 M NaCl, 10% glycerol, 10 mM β-mercaptoethanol) for elution. Subsequently, a buffer exchange was carried out by PD10 columns (Amersham Biosciences), which were eluted with 50 mM Tris-HCl, pH 8.0, 1 M NaCl, 10% glycerol, and 2 mM 1,4-dithiothreitol. Approximately 30 mg of purified

The volatiles of pathogenic and nonpathogenic mycobacteria and related bacteria

• Thorben Nawrath,
• Georgies F. Mgode,
• Bart Weetjens,
• Stefan H. E. Kaufmann and
• Stefan Schulz

Beilstein J. Org. Chem. 2012, 8, 290–299, doi:10.3762/bjoc.8.31

• (without glycerol) were washed in order to remove traces of ingredients from the stock-culture medium (7H9). Washing was done three times by mixing the culture (3 mL) with phosphate-buffered saline (PBS; 10 mL) and centrifuging at 4000 rpm for 10 min. Supernatants were decanted and PBS (10 mL) was added to

Biocatalytic hydroxylation of n-butane with in situ cofactor regeneration at low temperature and under normal pressure

• Svenja Staudt,
• Christina A. Müller,
• Jan Marienhagen,
• Christian Böing,
• Stefan Buchholz,
• Ulrich Schwaneberg and
• Harald Gröger

Beilstein J. Org. Chem. 2012, 8, 186–191, doi:10.3762/bjoc.8.20

• order to make sure that this result was not in fact due to a loss of activity of the glucose dehydrogenase from Bacillus sp. at low temperatures, the activity of this enzyme was determined at −10 °C (40 vol % of glycerol) and at −5 °C (30 vol % of glycerol). In this study, the glucose dehydrogenase

Synthesis of 2-amino-3-arylpropan-1-ols and 1-(2,3-diaminopropyl)-1,2,3-triazoles and evaluation of their antimalarial activity

• Matthias D’hooghe,
• Stéphanie Vandekerckhove,
• Karen Mollet,
• Karel Vervisch,
• Stijn Dekeukeleire,
• Liesbeth Lehoucq,
• Carmen Lategan,
• Peter J. Smith,
• Kelly Chibale and
• Norbert De Kimpe

Beilstein J. Org. Chem. 2011, 7, 1745–1752, doi:10.3762/bjoc.7.205

• emergence of multiple drug resistance to clinically established antimalarial drugs, however, there is a compelling need to introduce new chemicals that can overcome this resistance. In 2007, nitrogen-analogues of glycerol, which have a long-standing tradition in medicine as β-blockers, were introduced as a

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

• ]. From a formal point of view, reactions such as the lipase-catalyzed hydrolysis of triglycerides to glycerol and fatty acids, or amylase-catalyzed hydrolysis of amylose to glucose should also be classified as multistep-reaction processes, because they proceed stepwise via a sequence of intermediates

Fine-tuning alkyne cycloadditions: Insights into photochemistry responsible for the double-strand DNA cleavage via structural perturbations in diaryl alkyne conjugates

• Wang-Yong Yang,
• Samantha A. Marrone,
• Nalisha Minors,
• Diego A. R. Zorio and
• Igor V. Alabugin

Beilstein J. Org. Chem. 2011, 7, 813–823, doi:10.3762/bjoc.7.93

• on DNA cleavage In order to get further insight into the mechanism of the DNA cleavage by the three conjugates, we used the plasmid relaxation assays for the cleavage with conjugates 1, 6, and 7 in the presence of hydroxyl radicals (glycerol, DMSO) and singlet oxygen (NaN3) scavengers [65]. The

• hydroxyl radical scavengers, glycerol and DMSO, protected DNA from the cleavage by 33 and 26%, respectively, whereas NaN3 showed ~43% protection. The large protecting effect of NaN3, the singlet oxygen scavenger, is consistent with the efficient photoaddition reaction of its chromophore via triplet

• (Figure 8c). Only glycerol at pH 6 and glycerol and DMSO at pH 8 showed ~10% of protection. Little effect was observed for NaN3, suggesting that the formation of singlet oxygen via triplet energy transfer is inefficient, possibly because of a short triplet lifetime and fast intramolecular photocyclization

About the activity and selectivity of less well-known metathesis catalysts during ADMET polymerizations

• Hatice Mutlu,
• Lucas Montero de Espinosa,
• Oĝuz Türünç and
• Michael A. R. Meier

Beilstein J. Org. Chem. 2010, 6, 1149–1158, doi:10.3762/bjoc.6.131

• first time on the performance of two well-defined, stable Ru–indenylidene catalysts C1 and C2, and the “boomerang complex” C3 (Figure 2) during ADMET polymerizations. The ADMET monomer was synthesized by a procedure adapted from the literature using 1,3-propanediol, which can be prepared from glycerol

Poly(glycolide) multi-arm star polymers: Improved solubility via limited arm length

• Florian K. Wolf,
• Anna M. Fischer and
• Holger Frey

Beilstein J. Org. Chem. 2010, 6, No. 67, doi:10.3762/bjoc.6.67

• contrast to dendrimers, where functional groups are exclusively located at the surface, poly(glycerol) scaffolds also contain hydroxy groups throughout the structure. At first glance this might be considered a disadvantage, however, this is in fact beneficial for the significantly hydrophilized core

• crystallization tendencies of the polymer. Results and Discussion The hyperbranched poly(glycerol)s (PGs) with multiple poly(glycolide) arms were prepared by a straightforward two-step approach as shown in Figure 1. In the first step, we polymerized glycidol anionically by the method described previously [19

• secondary hydroxy groups of the polymer n(OH) is equal to the sum of the initiator functionality f and the degree of polymerization DPn. By varying of the initiator/monomer ratio, two hyperbranched poly(glycerol) samples with different degrees of polymerization DPn were obtained. Their theoretical number of

N-acylation of ethanolamine using lipase: a chemoselective catalyst

• Mazaahir Kidwai,
• Roona Poddar and
• Poonam Mothsra

Beilstein J. Org. Chem. 2009, 5, No. 10, doi:10.3762/bjoc.5.10

• (triacyl glycerol hydrolases EC 3.1.1.3) catalyze hydrolysis, esterification, transesterification, thioesterification, amidation, epoxidation etc. [5][6][7][8][9][10]. The use of immobilized lipases is on the rise, as these work well with non-aqueous media [11]. Apart from the convenient handling, these

Synthesis of new C^α-tetrasubstituted α-amino acids

• Andreas A. Grauer and
• Burkhard König

Beilstein J. Org. Chem. 2009, 5, No. 5, doi:10.3762/bjoc.5.5

• , 0.9 C, trans-COO). IR (neat) [cm−1]: = 2977, 2877, 2361, 1708, 1492, 1392, 1366, 1250, 1157, 1085, 1052, 940, 848. CI-MS (NH3): m/z 218.2 (9) [MH+ − 2 C4H8], 274.2 (51) [MH+ − C4H8], 330.2 (100) [MH+]. HR-MS (FAB, MeOH/glycerol) [MH+] calcd. for C17H32NO5 330.2280; found 330.2288. MF C17H31NO5. MW

• C, trans-COO). IR (neat) [cm−1]: = 3326, 2957, 2359, 1708, 1497, 1366, 1250,1160, 1116, 1098, 1055, 885, 849, 781. CI-MS (NH3): m/z (%) = 244.2 (25) [MH+ − Boc], 288.2 (44) [MH+ − C4H8], 305.2 (19) [MNH4+ − C4H8], 344.3 (100) [MH+]. HR-MS (FAB, MeOH/glycerol): [M+] calcd. for C18H33NO5 343.2359

• ); 170.7 (Cquat, 0.25 C, cis-COO). IR (neat) [cm−1]: = 3334, 2975, 2357, 1709, 1490, 1366, 1250, 1157, 1077, 949, 848. CI-MS (NH3): m/z (%) = 230.2 (18) [MH+ − Boc], 274.2 (30) [MH+ − C4H8], 291.2 (19) [MNH4+ − C4H8], 330.2 (100) [MH+], 676.6 (9) [2 M + NH4+]. HR-MS (FAB, MeOH/glycerol): [M+] calcd. for