Sulfokinases

Cormier, M. J., Hori, K., and Karkhanis, Y. D. (1970). Studies on the bioluminescence of Renilla reniformis. VII. Conversion of luciferin into luciferyl sulfate by luciferin sulfokinase. Biochemistry 9 1184-1189. 

This enzyme [EC 2.8.2.1], also known as phenol sulfo-transferase and sulfokinase, catalyzes the reaction of 3 -phosphoadenylylsulfate with a phenol to yield adenosine 3, 5 -bisphosphate and an aryl sulfate. The enzyme can utilize a number of aromatic compounds as substrates. 

Adrenal androgens also have a complex metabolic fate DHEA-S is formed in the adrenal cortex or by sulfokinases in the liver and kidney from DHEA and excreted by the kidney. DHEA and DHEA-S can be metabolized by 7a-and 16a-hydroxylases. 17p-Reduction of both compounds forms A -5-androstenediol and its sulfate. Androstenedione can be metabolized to androsterone after 3a- and 5a-reduction. 5P-Reduction results in the formation of etiocholanolone (see Eigure 51-7). These metabolites are conjugated to glucuronides and sulfates, which are then excreted in the urine. 

Estrone sulfokiiiase of rabbit liver has been separated from phenol sulfokinase by resin electrophoresis, but its specificity and general properties liave not yet been investigated (Nose and Lipmann, 1958). Further studies on this subject would be valuable, particularly regarding whether or not there are several estrogen sulfokiiiases and whether the phenolic or the alcoholic hydroxyl group is preferentially esterified. 

Phosphoadenosinephosphosulfate, y-phos-phoadnosine-S -phosphosuyate, adeuosine-y-phos-phale-5 -phosphosulfale, PAPS, active sulfate the product of sulfate activation. PAPS is a key intermediate in the reduction of sulfate and the formation of sulfote esters by sulfokinases. It is produced in a two stage reaction ... 

Polysaccharide suMate esters, polysaccharide sulfates sulfate esters of polysaccharides, synthesized by the action of sulfokinases. There are two possible mechanisms of biosynthesis 1. Sulfation of the polysaccharide chain by phosphoadenosinc phosphostil-fate (PAPS) 2. Polymer formation from sulfated sugar nucleotides. 

Sulfotransferase, sulfokinase an enzyme that catalyses the transfer of sulfuryl groups from phospho-adenosinephosphosulfate (PAPS) to oxygen and nitrogen functions of suitable acceptors. Transfer to an oxygen function (alcoholic and phenolic hydroxyl... 

A recent abstract and verbal report by McKhann, Levy, and Ho (1965) reports the in vitro synthesis of cerebroside sulfate by a microsomal enzyme system from young rat brain (18— 22 days old). Sonic irradiation of the microsomal fractions resulted in the solublization of a sulfokinase system. The complete synthesis required the microsomal fraction of brain, S04 , ATP, cerebrosides, and a non-ionic detergent (Bbij 96). The reaction reported would be consistant with equations 8, 9, and 10. No incorporation of S-sulfate into a cholesterol ester nor an exchange with unlabelled cerebroside sulfate was observed. 

Other studies establish the possibility of transconjugatioa between steroid ester sulfates and steroid glucuronides. Also, circumstantial evidence for the presence of different sulfokinases and sulfatascs has been observed. 

After perfusion of anencephalic term fetuses with labeled pregnenolone, about 47% of the radioactive material in the perfusate was found as glucuroni de.s and 45 % as steroid cst er sulfates (A laeyuma et al., 1970). These values, wliich are in contrast to those in normal fetuses, could be explained by a sulfokinase deficiency in the anencephalic fetu.s as a consequence of the adrenal atrophy. 

Crepy et oJ,., 1962 Shen et cd., 1963) is formfid in the maternal compartment. This last result confirms the relative physiological importance of the steroid sulfokinase activity in the fetal compartment. 

Fetal brain tissues also possess very active sulfokinases for dehydro-epjandro.steronc, and after incubation of tritium dehydroepiandrosterone with minced brain tissue from a human fetus in the twelfth week of gestation, 6% of the radioactive material consisted of ester sulfates (principally dehydroejnandrostcrone and androstenetriol sulfates). Moreover, the free fraction was largely metabolized to androstenediol, androstenetriol, and 16-ketoandrostenediol (Kiiapstein et al., 1968). 

Since no great difference was found in the concentrations of estrone and e.stradiol between the umbilical artery and the umbilical vein Maner et d., 1963), it is suggested that a small quantity of free estrone or estradiol or Ihnir sulfates oircuktes between the placenta and the fetus, and that most of the maternal urinary estrom and estradiol comes directly from the placental comjiartmerit. However, as well be discussed later (Section V, A), this last transfer is conditioned by the hydrolytic activity for estrone sulfate and estradiol sulfate in the placental compartment, and by tlie sulfokinase activity for cstroius and estradiol in the fetal compartment. 

It can be concluded that the very high sulfokinase activities in the fetus play an important role in the physiological function of active steroids but it is not yet established how these different enzymes are controlled. Xor is it yet known what the biological activity of these steroid conjugates is in this period of life, or how these steroid conjugates are transported, what is their half-life, and how they can be involved in the biological activities of steroid hormones in the fetal compartment. 

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