enzymology An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

, a steroid sulfotransferase () is an

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

that

catalyzes Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...

the

chemical reaction A chemical reaction is a process that leads to the chemistry, chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an Gibbs free energy, ...

:3'-phosphoadenylyl sulfate + a phenolic steroid

\rightleftharpoons

adenosine 3',5'-bisphosphate + steroid O-sulfate Thus, the two substrates of this enzyme are 3'-phosphoadenylyl sulfate and phenolic steroid, whereas its two

products Product may refer to: Business * Product (business), an item that can be offered to a market to satisfy the desire or need of a customer. * Product (project management), a deliverable or set of deliverables that contribute to a business solution ...

are adenosine 3',5'-bisphosphate and steroid O-sulfate. This enzyme belongs to the family of

transferase In biochemistry, a transferase is any one of a class of enzymes that catalyse the transfer of specific functional groups (e.g. a methyl or glycosyl group) from one molecule (called the donor) to another (called the acceptor). They are involved ...

s, specifically the sulfotransferases, which transfer sulfur-containing groups. The

systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivi ...

of this enzyme class is 3'-phosphoadenylyl-sulfate:phenolic-steroid sulfotransferase. This enzyme is also called steroid alcohol sulfotransferase. This enzyme participates in

steroid A steroid is an organic compound with four fused compound, fused rings (designated A, B, C, and D) arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes t ...

metabolism Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the co ...

Genes

Of 62 sulfotransferase genes in the human genome, 16 represent cytoplasmic sulfotransferases, and of these 16 cytoplasmic sulfotransferases, five have been found to act as steroid sulfotransferases. These five sulfotransferase genes are

SULT1A1 Sulfotransferase 1A1 is an enzyme that in humans is encoded by the ''SULT1A1'' gene. Sulfotransferase enzymes catalyze the sulfate conjugation of many hormones, neurotransmitters, drugs, and xenobiotic compounds. These cytosolic enzymes are dif ...

, SULT1E1, and

SULT2A1 Bile salt sulfotransferase also known as hydroxysteroid sulfotransferase (HST) or sulfotransferase 2A1 (ST2A1) is an enzyme that in humans is encoded by the ''SULT2A1'' gene. Function Sulfotransferase enzymes catalyze the sulfate conjugatio ...

, as well as the two isoforms of SULT2B1, SULT2B1a and SULT2B1b. Their substrate specificity is as follows: * SULT1A1:

Estradiol Estradiol (E2), also called oestrogen, oestradiol, is an estrogen steroid hormone and the major female sex hormone. It is involved in the regulation of female reproductive cycles such as estrous and menstrual cycles. Estradiol is responsible ...

(to estradiol sulfate) * SULT1E1: (to sulfate);

Estrone Estrone (E1), also spelled oestrone, is a steroid, a weak estrogen, and a minor female sex hormone. It is one of three major endogenous estrogens, the others being estradiol and estriol. Estrone, as well as the other estrogens, are synthesized ...

(to

estrone sulfate Estrone sulfate, also known as E1S, E1SO4 and estrone 3-sulfate, is a natural, endogenous steroid and an estrogen ester and conjugate. In addition to its role as a natural hormone, estrone sulfate is used as a medication, for instance in men ...

); Estradiol (to estradiol sulfate) * SULT2A1: (to sulfate);

Androsterone Androsterone, or 3α-hydroxy-5α-androstan-17-one, is an endogenous steroid hormone, neurosteroid, and putative pheromone. It is a weak androgen with a potency that is approximately 1/7 that of testosterone. Androsterone is a metabolite of te ...

(to androsterone sulfate);

Pregnenolone Pregnenolone (P5), or pregn-5-en-3β-ol-20-one, is an endogenous steroid and precursor/metabolic intermediate in the biosynthesis of most of the steroid hormones, including the progestogens, androgens, estrogens, glucocorticoids, and mineraloc ...

(to pregnenolone sulfate) * SULT2B1a: Pregnenolone (to pregnenolone sulfate) * SULT2B1b:

Cholesterol Cholesterol is the principal sterol of all higher animals, distributed in body Tissue (biology), tissues, especially the brain and spinal cord, and in Animal fat, animal fats and oils. Cholesterol is biosynthesis, biosynthesized by all anima ...

(to cholesterol sulfate) Traditionally, steroid sulfotransferases have been named according to their preferred substrate, for instance estrogen sulfotransferase (SULT1E1) and DHEA sulfotransferase (SULT2A1). However, cytosolic steroid sulfotransferases show broad substrate specificity, and SULT1E1 and SULT2A1 are not the only steroid sulfotransferases that sulfate estrogens and DHEA, respectively.

References

* EC 2.8.2 Enzymes of unknown structure {{2.8-enzyme-stub

Genes

See also

References