Structural basis for the broad range substrate specificity of a novel mouse cytosolic sulfotransferase—mSULT1D1

The mouse cytosolic sulfotransferase, mSULT1D1, catalyzes the sulfonation of a wide range of phenolic molecules including p-nitrophenol (pNP), α-naphthol (αNT), serotonin, as well as dopamine and its metabolites. To gain insight into the structural basis for its broad range substrate specificity, we solved two distinct ternary crystal structures of mSULT1D1, complexed with 3′-phosphoadenosine-5′-phosphate (PAP) plus pNP or PAP plus αNT. The structures revealed that the mSULT1D1 contains an L-shaped accepter-binding site which comprises 20 amino acid residues and four conserved water molecules. The shape of the accepter-binding site can be adjusted by conformational changes of two residues, Ile148 and Glu247, upon binding with respective substrates.     

Identification of unusual truncated forms of nucleocapsid protein in MDCK cells infected by Avian influenza virus (H9N2)

Unusual truncated forms of nucleocapsid protein (NP) were identified in the lysate of MDCK cells infected by Avian influenza virus (H9N2) using MS‐based proteomics approach. Moreover, O‐sulfonation that was considered as an unusual modification was identified in one of the tryptic peptides from the truncated NP. The findings might have implications on better understanding on the role of nucleoprotein in Avian influenza virus–host interaction.     

Sulfonation and anticoagulant activity of botryosphaeran from Botryosphaeria rhodina MAMB-05 grown on fructose

Botryosphaeran (EPS_FRU), an exopolysaccharide of the β-(1→3,1→6)-d-glucan type with 31% branching at C-6, is produced by the fungus Botryosphaeria rhodina MAMB-05 when grown on fructose as carbon source. Botryosphaeran was derivatized by sulfonation to induce anticoagulant activity. The effectiveness of the sulfonation reaction by chlorosulfonic acid in pyridine was monitored by the degree of substitution and FT-IR analysis of the sulfonated EPS_FRU (once sulfonated, EPS_FRU SULF; and re-sulfonated, EPS_FRU RESULF). Activated partial thromboplastin time (APTT) and thrombin time (TT) tests of EPS_FRU RESULF indicated significant in vitro anticoagulant activity that was dose-dependent. EPS_FRU did not inhibit any of the coagulation tests.     

Synthesis of novel water-soluble sulfonated cellulose

Water-soluble sulfonated cellulose (SC) samples were synthesized by oxidizing hardwood kraft pulp with sodium periodate followed by the sulfonation reaction with sodium bisulfite. Six levels of oxidation/sulfonation were obtained by using different mmols (0.93-4.67) of periodate per gram of pulp. The aldehyde and sulfonic acid contents, surface morphology, and water solubility property of these treated fibers were characterized. It was found that carbonyl group content increased with the periodate charge and so did the sulfonic acid content in subsequent sulfonation step. Scanning electron microscopy images showed a significant change in surface morphology of the sulfonated samples. Solubility of sulfonated cellulose in water was determined from ¹H NMR spectra and a solubility of 28.57 g/L was found when cellulose was oxidized with 4.67 mmol periodate per gram cellulose followed by the sulfonation reaction.     

Methylsulfonyl benzothiazoles (MSBT) derivatives: Search for new potential antimicrobial and anticancer agents

A series of novel 4 and 5-substituted methylsulfonyl benzothiazole (MSBT) compounds having amide, alkoxy, sulfonamide, nitro and amine functionality were synthesized from sequential reactions on 5-ethoxy-2-(methylsulfonyl)benzo[d]thiazole such as nitration, reduction, sulfonation, dealkylation, etc. All synthesized compounds were screened against antimicrobial and selected screened for anticancer activity. Antimicrobial activities studies reveled that among all compounds screened, out of MSBT-07, MSBT-11, MSBT-12, MSBT-14, MSBT-19, and MSBT-27 were found to have promising antimicrobial activity at MIC range of 4–50 μg/ml against selected bacterial as well as fungal species. Compounds having good antimicrobial activity were screened for cervical cancer (HeLA cell lines). Of these MSBT-07 and MSBT-12 significantly reduced the cell growth. Consequently their calculated GI₅₀ values were found to be 0.1 or <0.1 μM.     

Highly active, recyclable catalyst for the manufacture of viscous, low molecular weight, CO-ethene-propene-based polyketone, base component for a new class of resins

A highly active, recyclable homogeneous palladium(II) catalyst is described for the manufacture of viscous, low molecular weight CO-ethene-propene-based polyketone (CariliteOligomer), used for the manufacture of a new class of resins (CariliteResins). The catalyst is composed of palladium acetate, and a sulfonated diphosphine ligand, bdompp-S (1,3-bis(di-(2-methoxy, 5-sulfonatophenyl)phosphino)propane). In comparison with its non-sulfonated counterpart this catalyst not only exhibits a much more favourable partitioning coefficient in liquid-liquid separation of the polyketone product and solvent, but it also exhibits an approximately 2.5 times higher catalytic activity (up to 11.2 kg PK (g Pd)⁻¹ h⁻¹) in the manufacture of PK-PE-30 (polyketone terpolymer built up of CO, ethene and propene in a molar ratio of 100:30:70). A variety of salts were found to exert a positive influence on the activity of the catalyst. Possible origins of this ‘salt-effect’ are briefly discussed. The bdompp-S ligand was synthesised by sulfonation of bdompp using either a boric acid-oleum mixture or sulfuric acid as the sulfonation reagent. The product was isolated either as sodium-salt (bdompp-S[Na]₄·nNa₂SO₄), by extraction with methanol after neutralisation, or, in acidic, hydrated form (bdompp-S[H]₄·nH₂O), via a new and highly efficient procedure, i.e. cooling the reaction mixture after dilution with water. The X-ray crystal structure of bdompp-S[H]₄·nH₂O is discussed.     

The Biochemistry of Drug Metabolism – An Introduction

This review continues a general presentation of the metabolism of drugs and other xenobiotics begun in three recent issues of Chemistry & Biodiversity. The present Part is dedicated to reactions of conjugation, namely methylation, sulfonation, and phosphorylation, glucuronidation and other glycosidations, acetylation and other acylations, the formation and fate of coenzyme A conjugates, glutathione conjugation, and the reaction of amines with carbonyl compounds. It presents the many transferases involved, their nomenclature, relevant biochemical properties, catalytic mechanisms, and the reactions they catalyze. Nonenzymatic reactions, mainly of glutathione conjugation, also receive due attention. A number of medicinally, environmentally, and toxicologically relevant examples are presented and discussed.     

Chain conformation of sulfated derivatives of beta-glucan from sclerotia of Pleurotus tuber-regium

Six water-insoluble (1-->3)-beta-D-glucan fractions TM8-1 to TM8-6 with weight-average molecular mass Mw ranging from 5.76 to 77.4x10(4) obtained from the sclerotia of Pleurotus tuber-regium were sulfated to produce the water-soluble fractions S-TM8-1 to S-TM8-6 with Mw from 6.0 to 64.8x10(4). The degree of substitution (DS) of S-TM8 fractions was analyzed by elemental analysis (EA) to be 1.14-1.74. The 13C NMR results indicated that the C-6 was fully substituted, and C-2, C-4 were partially substituted by the sulfo-groups. The Mw and the intrinsic viscosity [eta] of the S-TM8 fractions were measured, respectively, by size-exclusion chromatography combined with laser light scattering (SEC-LLS), LLS and viscometry in phosphate buffer solution (PBS) at 37 degrees C. The dependences of [eta] and radius of gyration z(1/2) on Mw for the S-TM8 samples were found to be [eta]=1.89x10(-2) Mw(0.70) (cm3/g) and z(1/2)=1.12x10(-4) Mw(0.81) (nm) in the Mw range tested. Based on current theories for a wormlike chain model, the molar mass per unit contour length ML and persistence length q of the S-TM8 were calculated to be 990 nm(-1) and 8.5 nm, respectively. The relatively higher q value suggested a more expanded flexible chain of S-TM8 in PBS. The water-solubility and relatively expanded chain conformation of the STM8 fractions were considered to be significant to their antiviral activity.     

Analysis of acidic peptides with a matrix-assisted laser desorption/ionization mass spectrometry using positive and negative ion modes with additive monoammonium phosphate

Acidic PTMs such as phosphorylation and sulfonation of proteins are known to play important roles in many cellular processes including signal transductions and protein-protein interactions. In MS, the acidic modified peptides, that have negative charge, are observable in negative ion mode rather than in positive ion mode. Moreover, addition of ammonium salt into MALDI matrix solution improves the relative intensity of ionization of the phosphorylated peptide to unmodified one. We demonstrate that a combination of the negative ion mode and addition of ammonium salt is more effective in the ionization of the acidic modified peptides. We applied this method to 2-DE separated proteins of Caenorhabditis elegans. As a result, 42 spots were identified as modified proteins, of which 34 proteins were nonoverlapping unique proteins. Furthermore, our study revealed that pI shifts of the DIM-1 and MLC-1 proteins in the 2-DE gel were attributed to the presence of the acidic modifications. The negative ion mode together with the addition of ammonium salt provides us a useful method to detect the phosphorylation and/or sulfonation of protein in a simple manner.     

Solvolytic depolymerization of chondroitin and dermatan sulfates

It is essential to establish a library of glycosaminoglycan oligosaccharides from the chondroitin and dermatan sulfates to investigate their biological functions and structure-activity relationships (SARs). There are several approaches to obtain oligosaccharides using chemical and enzymatic degradation procedures; however, purification of each resulting oligosaccharide is complicated because of the diversity of sulfonation patterns present in these oligosaccharides. We have developed a new method for the solvolytic degradation for chondroitin and dermatan sulfates to obtain an oligosaccharide mixture that can be easily purified into chondro/dermato oligosaccharides for characterization by both ¹H NMR and MALDI-TOFMS. These oligosaccharides have a methyl-esterified uronate residue and a methyl 2-acetamido-2-deoxy-d-galactofuranoside at the nonreducing and reducing ends, respectively. All other internal repeating disaccharide units were desulfonated, but maintained their core carbohydrate structures.