Arylsulfotransferase from Clostridium innocuum—A new enzyme catalyst for sulfation of phenol‐containing compounds

Abstract

Arylsulfotransferase (AST, EC 2.8.2.22), an enzyme capable of sulfating a wide range of phenol-containing compounds was purified from a Clostridium innocuum isolate (strain 554). The enzyme has a molecular weight of 320 kDa and is composed of four subunits. Unlike many mammalian and plant arylsulfotransferases, AST from Clostridium utilizes arylsulfates, including p-nitrophenyl sulfate, as sulfate donors, and is not reactive with 3-phosphoadenosine-5'-phosphosulfate (PAPS). The enzyme possesses broad substrate specificity and is active with a variety of phenols, quinones and flavonoids, but does not utilize primary and secondary alcohols and sugars as substrates. Arylsulfotransferase tolerates the presence of 10 vol% of polar cosolvents (dimethyl formamide, acetonitrile, methanol), but loses significant activity at higher solvent concentrations of 30-40 vol%. The enzyme retains high arylsulfotransferase activity in biphasic systems composed of water and nonpolar solvents, such as cyclohexane, toluene and chloroform, while in biphasic systems with more polar solvents (ethyl acetate, 2-pentanone, methyl tert-butyl ether, and butyl acetate) the enzyme activity is completely lost. High yields of AST-catalyzed sulfation were achieved in reactions with several phenols and tyrosine-containing peptides. Overall, AST studied in this work is a promising biocatalyst in organic synthesis to afford efficient sulfation of phenolic compounds under mild reaction conditions.

The First Successful Crystallographic Characterization of a Cyclodextrin Dimer: Efficient Synthesis and Molecular Geometry of a Doubly Sulfur‐Bridgedβ‐Cyclodextrin

“…The involvement of a histidine residue having this value is less likely, since the pK a for histidine is usually lower 31. Mozhaev et al reported that the AST from Clostridium innocuum has optimal activity at slightly lower pH (8.0–8.5) 12…”

“…Additionally, in order to prevent side reactions of labile functionalities and to enhance the chemo‐ or regioselectivity of the overall reaction, these functionalities have to be protected 9–11. Enzymatic methods for sulfation of compounds under mild conditions may have clear advantages and the possibility to use enzymes for this purpose has been studied 12–14…”

“…However, the ASTs are highly interesting for biotransformation purposes because of the lower cost and higher stability of p ‐NPS compared to PAPS. Since the enzymes also have a broader substrate specificity12 these enzymes may be potentially useful in the selective and mild sulfation of many compounds such as peptides, steroids and carbohydrates. Here we report successful cloning and expression of the astA gene from Desulfitobacterium hafniense and explored its donor and acceptor specificity.…”

Arylsulfate sulfotransferase

“…flavine, chalcone, xanthone are sulfated, tyrosine-containing peptides, e.g. enkephalin, LH-RH, vasopressin, angiotensin, proctorin, cholecystokinin octopeptide, phyllocerulein are sulfated with high yield, hydroxyl groups of tyrosine residues in peptides such as angiotensin can act as acceptors, does not act on 3'-phosphoadenylylsulfate or adenosine 3',5'bisphosphate [1]; <8> enzyme does not react with 3-phosphoadenosine-5'-phosphosulfate, primary alcohols, secondary alcohols and sugars [13]; <1> enzyme does not react with 3-phosphoadenosine-5'-phosphosulfate [14]) [1, 13, 14] P ?…”