Enzymes from human articular cartilage: isolation of arylsulfatase B and its comparison with arylsulfatase A

Detection, production, and application of microbial arylsulfatases

Arylsulfatases are enzymes which catalyze the hydrolysis of arylsulfate ester bonds to release a free sulfonate. They are widespread in nature and are found in microorganisms, most animal and human tissues, and plant seeds. However, this review focuses on arylsulfatases from microbial origin and gives an overview of different assays and substrates used to determine the arylsulfatase activity. Furthermore, the production of microbial arylsulfatases using wild-type organisms as well as the recombinant production using Escherichia coli and Kluyveromyces lactis as expression hosts is discussed. Finally, various potential applications of these enzymes are reviewed.

Monensin stimulation of arylsulfatase B activity in human chondrocytes

Secreted and intracellular arylsulfatase B (ASB) activities were measured in normal and osteoarthritic (OA) human chondrocyte cultures in the absence and presence of monensin, ammonium chloride, and chloroquine. Of the three agents added, only monensin produced a significant stimulation of secreted enzyme activity. Osteoarthritic cells consistently exhibited a three-fold higher level of secreted specific ASB activity than did normal cells, with or without monensin. When compared with normal cells, OA cells also consistently exhibited a twofold heightened intracellular specific enzyme activity both in the absence or presence of monensin. With increasing dosage of monensin, secreted and intracellular ASB activity increased for both OA and normal cells. Total enzyme activity of secreted and intracellular ASB was found to be cell density dependent. No inhibition of secreted or intracellular ASB activity was observed for sparsely plated cultures. In contrast to sparse cultures, an inhibition of secreted ASB, with or without monensin, was observed in densely plated cultures. Intracellular total activity was not inhibited by high-density cultures. Secreted ASB activity was found to be time-dependent after passage. Enzyme activity was maximal at 6 h in both OA and normal cells and decreased by the end of 24 h both in serum-free medium and in serum-free medium with monensin. When compared with normal cells, OA cells expressed higher levels of ASB activity under all test conditions. This heightened activity therefore appears to be a property inherent in the OA chondrocyte.

Characteristics of human chondrocyte cultures in completely defined medium

Chondrocytes derived from normal human adult articular cartilage were established and maintained for over 5 months in a completely defined medium without the addition of serum or any other growth factors. At the end of 5 months, these cells were still metabolically active. The cells incorporated [3H] thymidine into DNA, incorporated [35S] sulfate into proteoglycans, and exhibited lysosomal enzyme activities. The 35S-labeled proteoglycans isolated from the culture medium had elution profiles on high pressure liquid chromatography (HPLC) similar to those observed for proteoglycans from other mammalian sources. This self-contained growth competence may reflect a need produced by the unusual avascular and alymphatic character of articular cartilage.