- Synthesis, characterization, kinetic parameters, and diagnostic application of a sensitive colorimetric substrate for β-galactosidase (2-chloro-4-nitrophenyl-β-D-galactopyranoside)
-
The synthesis and characterization of 2-chloro-4-nitrophenyl β-D-galactopyranoside, an improved chromogenic substrate for β-galactosidase, is described. The important kinetic parameters (Km, Vmax and Kp) for this substrate were compared with those of other substrates. The diagnostic utility of this substrate in a digoxin liposome immunoassay is discussed. The new substrate offers at least four times the sensitivity enhancement as that with ortho-nitrophenyl β-D-galactopyranoside in the assays for β-galactosidase. This substrate should find use in enzyme immunoassays where βgalactosidase is used as a label. Copyright
- Hwang,Scott
-
-
Read Online
- An Efficient Strategy for the Chemo-Enzymatic Synthesis of Bufalin Glycosides with Improved Water Solubility and Inhibition against Na+, K+-ATPase
-
In this study, bufalin was glycosylated by an efficient chemo-enzymatic strategy. Firstly, 2-chloro-4-nitrophenyl-1-O-β-D-glucoside (sugar donors) was obtained by chemical synthesis. Then, the glycosylation of the bufalin was achieved with the synthesized sugar donor under the catalysis of two glycosyltransferases (Loki and ASP). Finally, two glycosides, i. e., bufalin-3-O-β-D-glucopyranoside and bufalin-3-O-[β-D-glucopyranosyl-(1→2)-β-D-glucopyranoside)], were obtained by preparative HPLC. Compared to our previously reported sole chemical (total yield 10 % in four steps) or enzymatic methods (30 %), our combined chemo-enzymatic strategy in this article greatly improves the yields of monoglycoside (68 %) and diglycoside (21 %) and decreased the experimental cost (90 %). Furthermore, we tested the water solubility of these glycosides and found that the water solubilities of the two glycosides were 13.1 and 53.7 times of bufalin, respectively. In addition, the inhibitory activity of these glycosides against Na+, K+-ATPase were evaluated. The mono-glycosylated compound showed more potent activity than bufalin, while the diglycosylated compound was less potent.
- Liu, Yan,Xu, Wei,Huang, Zhao-He,Guo, Jun,Jiang, Ren-Wang
-
-
- Binuclear copper(II) complexes discriminating epimeric glycosides and α- And β-glycosidic bonds in aqueous solution
-
Two chiral binuclear copper(II) complexes were synthesized and characterized for the first time as efficient chemoselective catalysts for the hydrolysis of aryl glycosides and disaccharides in aqueous solution at near neutral pH. Under these conditions, discrimination of epimeric aryl α-glycopyranosides was observed by both 29-fold different reaction rates and 3-fold different proficiency of the catalyst. Additionally, large differentiation of the nature of α- and β-glycosidic bond in aryl glycosides as model compounds is apparent, but also noted in selected disaccharides. The influence of the chirality of the complexes and the role of the configuration of the carbohydrate upon interaction with the catalyst is discussed in detail. Lastly, a putative mechanism for the metal complex-catalyzed hydrolysis is derived from the experimental evidence pointing at deprotonation of the hydroxyl group at C-2 as a pre-requisite for glycoside hydrolysis.
- Striegler, Susanne,Fan, Qiu-Hua,Rath, Nigam P.
-
p. 349 - 364
(2016/05/24)
-
- Facile and Versatile Chemoenzymatic Synthesis of Enterobactin Analogues and Applications in Bacterial Detection
-
Siderophores, such as enterobactin (Ent), are small molecules that can be selectively imported into bacteria along with iron by cognate transporters. Siderophore conjugates are thus a promising strategy for delivering functional reagents into bacteria. In this work, we present an easy-to-perform, one-pot chemoenzymatic synthesis of functionalized monoglucosylated enterobactin (MGE). When functionalized MGE is conjugated to a rhodamine fluorophore, which affords RhB-Glc-Ent, it can selectively label Gram-negative bacteria that utilize Ent, including some E. coli strains and P. aeruginosa. V. cholerae, a bacterium that utilizes linearized Ent, can also be weakly targeted. Moreover, the targeting is effective under iron-limiting but not iron-rich conditions. Our results suggest that the RhB-Glc-Ent probe is sensitive not only to the bacterial strain but also to the iron condition in the environment.
- Lee, Albert A.,Chen, Yi -Chen S.,Ekalestari, Elisa,Ho, Sheng -Yang,Hsu, Nai -Shu,Kuo, Tang -Feng,Wang, Tsung -Shing Andrew
-
p. 12338 - 12342
(2016/10/13)
-
- Evaluating N-benzylgalactonoamidines as putative transition state analogs for β-galactoside hydrolysis
-
Experimental evidence is provided for p-methylbenzyl-d-galactonoamidine to function as a true transition state analog for the enzymatic hydrolysis of aryl-β-d-galactopyranosides by β-galactosidase (A. oryzae). The compound exhibits inhibition constants in the low nanomolar concentration range (12-56 nM) for a selection of substrates. Along these lines, a streamlined synthetic method based on phase-transfer catalysis was optimized to afford the required variety of new aryl-β-d-galactopyranosides. Last, the stability of the galactonoamidines under the assay conditions was confirmed. This journal is the Partner Organisations 2014.
- Fan, Qiu-Hua,Striegler, Susanne,Langston, Rebekah G.,Barnett, James D.
-
p. 2792 - 2800
(2014/05/06)
-
- Natural product disaccharide engineering through tandem glycosyltransferase catalysis reversibility and neoglycosylation
-
A two-step strategy for disaccharide modulation using vancomycin as a model is reported. The strategy relies upon a glycosyltransferase-catalyzed 'reverse' reaction to enable the facile attachment of an alkoxyamine-bearing sugar to the vancomycin core. Ne
- Peltier-Pain, Pauline,Marchillo, Karen,Zhou, Maoquan,Andes, David R.,Thorson, Jon S.
-
supporting information
p. 5086 - 5089
(2013/01/15)
-
- Synthesis and evaluation of glycosyl donors with novel leaving groups for transglycosylations employing β-galactosidase from bovine testes
-
Novel aryl β-d-galactopyranosides were synthesized employing phase-transfer catalysis, and assayed as potential galactose donors in the presence of β-galactosidase from bovine testes using pNP-Gal as a reference. The aglycones were represented mainly by nitrophenols containing halogens, hydroxymethyl, aldehyde, carboxyl, ester or amino functions. An unusual intermolecular acetyl migration onto the benzylic alcohol group was observed during galactosylation of hydroxymethylnitrophenols. Pyridyl glycosides were obtained by reaction with the corresponding silver pyridinolates. Glycosides of halo-, hydroxymethyl- or methoxycarbonyl-nitrophenols as leaving groups gave virtually the same yields of transglycosylation products. A minor increase was achieved with nitrosalicylaldehyde as leaving group, whereas carboxy or amino derivatives gave very low or no yield of the transglycosylation product. Commercially available donors such as resorufinyl and 4-methylumbelliferyl β-d-galactopyranosides exhibited a lower transglycosylation potential than these novel pNP-Gal derivatives.
- Kroeger, Lars,Thiem, Joachim
-
p. 467 - 481
(2008/03/13)
-
- Examination of the active sites of human salivary α-amylase (HSA)
-
The action pattern of human salivary amylase (HSA) was examined by utilising as model substrates 2-chloro-4-nitrophenyl (CNP) β-glycosides of maltooligosaccharides of dp 4-8 and some 4-nitrophenyl (NP) derivatives modified at the nonreducing end with a 4,6-O-benzylidene (Bnl) group. The product pattern and cleavage frequency were investigated by product analysis using HPLC. The results revealed that the binding region in HSA is longer than five subsites usually considered in the literature and suggested the presence of at least six subsites; four glycone binding sites (-4, -3, -2, -1) and two aglycone binding sites (+1, +2). In the ideal arrangement, the six subsites are filled by a glucosyl unit and the release of maltotetraose (G4) from the nonreducing end is dominant. The benzylidene group was also recognisable by subsites (-3) and (-4). The binding modes of the benzylidene derivatives indicated a favourable interaction between the Bnl group and subsite (-3) and an unfavourable one with subsite (-4). Thus, subsite (-4) must be more hydrophylic than hydrophobic. As compared with the action of porcine pancreatic α-amylase (PPA) on the same substrates, the results showed differences in the three-dimensional structure of active sites of HSA and PPA. (C) 2000 Elsevier Science Ltd.
- Kandra, Lili,Gyemant, Gyoengyi
-
p. 579 - 585
(2007/10/03)
-
- Study of the action of human salivary alpha-amylase on 2-chloro-4-nitrophenyl α-maltotrioside in the presence of potassium thiocyanate
-
The degradation mechanism of a synthetic substrate, 2-chloro-4-nitrophenyl α-maltotrioside (CNP-G3), by human salivary alpha-amylase (HSA) was investigated by kinetic and product analyses. It was observed that the enzyme attacked the various CNP-maltooligosaccharides (CNP-G3, to CNP-G6) releasing free CNP. Addition of 500 mM potassium thiocyanate (KSCN) was also found to greatly increase the rates of CNP-release. It was the fastest with CNP-G3, and, in the presence of KSCN, was almost comparable to that of degradation of maltopentaose (G5). On the other hand, addition of KSCN decreased the rate of cleavage between glucan-glucan bonds in maltopentaose. Product analysis showed that KSCN addition altered the cleavage distribution which occurred 100% at the bond between CNP and G3, and that product distribution of free CNP was largely dependent on substrate concentration. Formation of CNP-G6, a larger product than the original substrate CNP-G3, was found to be present in the digest at high concentrations of substrate and in the presence of KSCN. Based on these results, a degradation pathway for CNP-G3 involving transglycosylation besides direct hydrolysis is proposed. The increase of the CNP-release by the addition of KSCN would result from a corresponding increase in the interaction between the CNP moiety and the corresponding subsite near the catalytic site, as well as the enhancement of the catalytic efficiency.
- Suganuma, Toshihiko,Maeda, Yoshiaki,Kitahara, Kanefumi,Nagahama, Tomonori
-
p. 219 - 227
(2007/10/03)
-
- Substrates for β-galactosidase
-
A substrate for β-galactosidase having the general formula STR1 wherein X is halogen; Y is halogen, lower alkyl or hydrogen; W is lower alkyl or hydrogen; and Z is nitro.
- -
-
-
