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.

[Lysosomal membrane glycoprotein lamp2a--receptor for chaperone-mediated degradation of cytosolic proteins]. / Lizosomalna blonowa glikoproteina lamp2a--receptor dla cytosolowych bialek przeznaczonych do selektywnej proteolizy.

The structure of several lysosomal membrane glycoproteins (lamp1, lamp2, limpI and limpII) has been described. The significance of the receptor glycoprotein lamp2a in the chaperone-mediated autophagy of cytosolic proteins with KFERQ motif has been described in details as well as the chaperone protein Hsc73 and other chaperones involved in this process. Several modulatory mechanisms of the chaperone-mediated autophagy, which is activated in condition of stress and starvation, were also outlined.

[Nongenomic action of aldosterone on cellular metabolism]. / Pozagenomowe oddzialywania aldosteronu na procesy metaboliczne komórek.

In addition to the well-known genomic action of aldosterone, resulting in delayed effect (1-2 h), a very rapid nongenomic effect (1-2 min) of aldosterone has been recognized recently. The nongenomic action pathway of aldosterone involves: signal perception by protein membrane receptors, induction of the synthesis of messenger molecules such as cAMP, IP3, and DAG, and a change of Ca2+ concentration in the cell cytosol. The target of these rapid responses are also ion channels and exchangers. The nongenomic mechanisms of aldosterone action cooperate with its genomic action in some instances.

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.