Cholesterol sulphate sulphohydrolase from human placenta microsomes--purification and properties of the dephosphorylated form of enzyme

Cholesterol sulphate sulphohydrolase of human placenta lysosomal membrane

In this paper we report that the activity of cholesterol sulphate sulphohydrolase (CHS-ase) is associated with the lysosomal membranes. The procedure of purification of CHS-ase from human placenta lysosomes was elaborated. The purified enzyme is highly specific to cholesterol sulphate (specific activity 2126.60+/-940.90 nmol min(-1) mg protein(-1)) and acts optimally at pH 3.4. The K(M) value for the hydrolysis of cholesterol sulphate is 3.6+/-0.95 x 10(-5)mol/l. The isoelectric point (pI) has the value 5.7, molecular weight estimated by SDS-PAGE electrophoresis is 38 kDa. The described enzyme may be involved in a regulation of cholesterol and cholesterol sulphate levels in the lysosomal membrane.

Dehydroepiandrosterone sulphate sulphohydrolase [correction of sulphoydrolase] from human placenta microsomes--properties of the purified enzyme

A form of steroid sulphate sulphohydrolase (EC 3.1.6.2) hydrolysing the dehydroepiandrosterone sulphate (DHEAS-ase) was purified from human placenta microsomes. During the purification procedure the DHEAS-ase was separated from the oestrone sulphate sulphohydrolase (OS-ase). The purified DHEAS-ase revealed specific activity of 1520 nmolxmin-1xmgprotein-1 and exhibited optimal activity at pH 8.4. The Km value was established to be 3.3+/-0.07x10(-5) M. The pI value was around 8.7. The molecular weight estimated by gel filtration was 7.4 kDa. The purified DHEAS-ase was not sensitive to the common sulphohydrolase inhibitors, such as phosphate, sulphate and sulphide ions, but was inhibited by several phosphohydrolase inhibitors (ammonium molybdate, vanadium oxide(V), zinc acetate). Steroids effected inhibition or activation of the purified enzyme. The data concerning substances reacting with -SH groups suggest that in the physiological conditions DHEAS-ase is controlled by the redox status of the cell.

Sterolsulphate sulphohydrolase from human placenta microsomes--30 kDa molecular weight form of cholesterol sulphate sulphohydrolase

The cholesterol sulphate sulphohydrolase (CHS-ase) exhibiting molecular weight of 30 kDa was purified from human placenta microsomes. The microsomal proteins were extracted with 0.5% Triton X-100. The DEAE-cellulose chromatography of the solubilized microsomal proteins, performed at pH 7.6 allowed to separate two enzymatically active fractions. One of them was associated with the protein fraction unbound by DEAE-cellulose, the other was tightly bound by ion exchanger. The 30 kDa cholesterol sulphate sulphohydrolase was purified to homogenity from the protein fraction tightly bound by DEAE-cellulose. The highly purified enzyme preparation (specific activity 385 nmol min(-1)mg(-1) of protein) exhibited optimal activity at pH 6.4, the K(m) was established to be 6.7 x 10(-6)M, the pI value was 7.4. The 30 kDa cholesterol sulphate sulphohydrolase, in contrast to the CHS-ase form originated from the protein fraction unbound by DEAE-cellulose, was not sensitive to alkaline phosphatase treatment and phosphohydrolase inhibitors. The effects of steroids, -SH reacting agents and sulphohydrolase inhibitors on the enzyme activity were tested.