Kinetic studies of the phenol sulphotransferase reaction

Banerjee, Ranajit K.; Roy, A.B.

doi:10.1016/0005-2744(68)90004-1

Cited by 51 publications

(13 citation statements)

References 18 publications

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“…Early studies on partially purified gpPST and rPST supported a random bi-bi mechanism with rapid equilibration. [58,59] Possibly conflicting results were obtained from studies on PST isolated from rat brain; in this case an ordered sequential mechanism with an E·PAP·ROH dead-end complex was proposed. [60] The results of the most comprehensive study to date (binding, initial reaction rates, and inhibition data), which was carried out on apparently homogeneous AST-IV (rSULT1C1) from rat liver, were in agreement with this mechanism.…”

Section: Sequential Mechanismsmentioning

confidence: 96%

Sulfotransferases: Structure, Mechanism, Biological Activity, Inhibition, and Synthetic Utility

et al. 2004

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The sulfonation (also known as sulfurylation) of biomolecules has long been known to take place in a variety of organisms, from prokaryotes to multicellular species, and new biological functions continue to be uncovered in connection with this important transformation. Early studies of sulfotransferases (STs), the enzymes that catalyze sulfonation, focused primarily on the cytosolic STs, which are involved in detoxification, hormone regulation, and drug metabolism. Although known to exist, the membrane-associated STs were not studied as extensively until more recently. Involved in the sulfonation of complex carbohydrates and proteins, they have emerged as central players in a number of molecular-recognition events and biochemical signaling pathways. STs have also been implicated in many pathophysiological processes. As a result, much interest in the complex roles of STs and in their targeting for therapeutic intervention has been generated. Progress in the elucidation of the structures and mechanisms of sulfotransferases, as well as their biological activity, inhibition, and synthetic utility, are discussed in this Review.

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Section: Sequential Mechanismsmentioning

confidence: 96%

Sulfotransferases: Structure, Mechanism, Biological Activity, Inhibition, and Synthetic Utility

et al. 2004

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“…3 and 4). Substrate inhibition by the acceptor has also been observed by Banerjee & Roy (1968) and Foldes & Meek (1973) for the guinea-pig liver and rat brain phenol sulphotransferase reactions respectively. However, these workers did not study the type of substrate inhibition.…”

Section: Discussionmentioning

confidence: 84%

“…In this respect Banerjee & Roy (1968) reported that the mechanism of the reaction catalysed by phenol sulphotransferase from guineapig liver was a rapid-equilibrium random mechanism, but the experiments were carried out at pH 5.6, the apparent pH optimum for the enzyme with pnitrophenol as the sulphate acceptor. These authors also observed substrate inhibition by the sulphate acceptor and found it to be dependent on the pH: it was not observed at pH5.6, but became increasingly obvious at pH values greater than 6.2.…”

Section: Discussionmentioning

confidence: 99%

Kinetics and mechanism of the rat brain phenol sulphotransferase reaction

Pennings¹,

Vrielink²,

Kempen³

1978

Biochemical Journal

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Some properties of rat brain phenol sulphotransferase were investigated in vitro at pH 7.4. The enzyme was purified 10-fold by chromatography on DEAE-Sephadex A-50. It can be assayed with 4-hydroxy-3-methoxyphenylethylene glycol or 4-methylumbelliferone as the sulphate acceptor. The partially purified enzyme is stable for at least 1 week when stored at 4°C. It is, however, additionally activated (10-20%) and stabilized by mM-dithiothreitol. The activity of the enzyme does not depend on the addition of exogenous Mg2+. The pH optima for the sulphation of 4-hydroxy-3-methoxyphenylethylene glycol and 4-methylumbelliferone are 7.8 and 7.4 respectively. Substrate inhibition by the sulphate acceptor is apparent at concentrations over 0.05 mm. Initial-velocity studies in the absence and presence of product and dead-end inhibitors suggested that the mechanism of the rat brain sulphotransferase reaction is sequential ordered Bi Bi with a dead-end complex of enzyme with adenosine 3',5'-bisphosphate and sulphate acceptor. The sulphate donor adenosine 3'-phosphate 5'-sulphatophosphate is the first substrate that adds to the enzyme, and the sulphate acceptor is the second substrate. The dissociation constant for the complex of enzyme with sulphate donor is 21 AM. The sulphated substrate is the first product and adenosine 3',5'-bisphosphate is the second product that leaves the enzyme.

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“…2. 1) from guinea-pig liver (Banerjee & Roy, 1968), and the mechanism has been confirmed, by employing product inhibition studies (Cleland, 1963), as that of a rapid-equilibrium random Bi Bi reaction. The variation, with pH, of Km and Vmax.…”

Section: Methodsmentioning

confidence: 87%

“…transferase activity towards L-tyrosine methyl ester. ENZYMIC SULPHATION OF (Orsi & Spencer, 1964) and phenol sulphotransferase (Banerjee & Roy, 1968). Dalziel (1957) considered a number of possible mechanisms for two-substrate enzymic reactions and drew up characteristic relationships between the measured kinetic constants for each mechanism considered.…”

Section: Methodsmentioning

confidence: 99%

The effect of substrate concentration and pH on the enzymic sulphation of l-tyrosyl derivatives

Mattock¹,

Barford²,

Basford³

et al. 1970

Biochemical Journal

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1. The kinetics of the enzymic transfer of sulphate from adenosine 3'-phosphate 5'[35S]-sulphatophosphate to derivatives of L-tyrosine were investigated with a partially purified enzyme preparation from rat liver. 2. At pH 7.5 and 370C the Km values for L-tyrosine methyl ester and adenosine 3'-phosphate 5'[35S]-sulphatophosphate are 0.3mM and 8nM respectively. The Km value for either substrate is independent of the concentration of the other. The available data are consistent with the sulphation reaction proceeding according to a rapid-equilibrium random Bi Bi mechanism. 3. From the effect of pH on the Km and Vmax. values for L-tyrosine methyl ester, tyramine and N-acetyl-L-tyrosine ethyl ester it is concluded that the enzyme is specific for substrate molecules with a free and unprotonated amino group and an un-ionized hydroxyl group. 4. The only ionizing group that can be positively attributed to the enzyme appears to influence the binding of adenosine 3'-phosphate 5'[35S]-sulphatophosphate and has an apparent pK value of approx. 9.5. It is suggested that this group may be an essential thiol. 5. The enzyme is inhibited by iodoacetamide at pH 7.5 and 30°C and this inhibition is prevented by the presence of adenosine 3'-phosphate 5'[35S]-sulphatophosphate but not by L-tyrosine methyl ester.The preceding paper (Mattock & Jones, 1970) contrasted some of the properties of the enzymes responsible for the sulphation of L-tyrosine methyl ester and tyramine on the one hand and p-nitrophenol on the other. From the evidence quoted, it appears that the two enzymes are distinct from one another. Hence it is not likely that the appearance of L-tyrosine 0-sulphate in mammalian urines (John, Rose, Wusteman & Dodgson, 1966) is an artifact of a detoxication type of reaction. However, whether the enzyme that catalyses the sulphation of simple derivatives of L-tyrosine is responsible for the appearance of sulphated tyrosine residues in proteins is unknown, and an investigation of the substrate requirements of this enzyme may throw light on its possible metabolic function. In this connexion, Segal & Mologne (1959) have shown that, with a rat liver enzyme preparation, the rate of transfer of sulphate from p-nitrophenyl sulphate via adenosine 3',5'-diphosphate to carboxyl-substituted derivatives of L-tyrosine was higher at pH 9.3 than at pH 7.8. These authors suggested that these observations reflected the ionization of the amino group of the substrates in

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Kinetic studies of the phenol sulphotransferase reaction

Cited by 51 publications

References 18 publications

Sulfotransferases: Structure, Mechanism, Biological Activity, Inhibition, and Synthetic Utility

Sulfotransferases: Structure, Mechanism, Biological Activity, Inhibition, and Synthetic Utility

Kinetics and mechanism of the rat brain phenol sulphotransferase reaction

The effect of substrate concentration and pH on the enzymic sulphation of l-tyrosyl derivatives

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