Lysosomes, hyaluronidase

Lysosomal hyaluronidase possesses transglycosylation properties using octo-saccharides as a substrate, rather than hexasaccharides like testicular hyaluronidase [14, lti]. 

Lepperdinger, G., Strobl, B., and Kreil, G., HYAL2, a human gene expressed in many cells, encodes a lysosomal hyaluronidase with a novel type of specificity. J. Biol. Chem., 273, 22466, 1998. 

Bollet et al. [11] demonstrated the presence of hyaluronidase activity in various mammalian tissues. They showed that this type of hyaluronidase differed from the testicular type concerning pH optimum and pH range of activity. Subsequent studies revealed that the enzyme was present in the lysosomal fraction of the tissues [12]. The liver is an especially rich source [13]. Degradation of hyaluronan leads to the same end products as testicular hyaluronidase [11]. Lysosomal hyaluronidase from rat liver degrades chondroitin-4- and -6-sulfate, but not dermatan sulfate, desulfated dermatan sulfate, heparan sulfate, keratan sulfate, or heparin [14], Lysosomal hyaluronidase has an acid pH optimum and a narrow pH range of activity [14]. This difference in pH profile of activity has commonly been used to differentiate between testicular and lysosomal hyaluronidase. A similar acid-active hyaluronidase is present in human serum [15]. 

Hyaluronidase has an absolute requirement for cations, as dialyzed preparations show no activity toward dialyzed substrates. K+, Na+, Ca2+, Mg2+, and Mn2+ all have stimulating properties toward hyaluronidase. The monovalent cations show the strongest stimulating effects and act over a broader range of concentration than divalent cations [50]. Testicular, serum, and lysosomal hyaluronidase seem to have different sensitivities toward NaCl [54,61]. A noncompetitive mechanism was proposed to explain the activation of hyaluronidase by Na+ [59,62]. 

B. Fiszer-Szafarz and D. Szafarz. Lysosomal hyaluronidase activity in normal rat liver and in chemically induced hepatomas. Cancer Res. 55 1104 (1973). 

G. N. DeMartino and A. L. Goldberg. A possible explanation of myxededema and hypercholesterolemia in hypothyroidism control of lysosomal hyaluronidase and cholesterol esterase by thyroid hormones. Enzyme 26 1 (1981). 

Aronson, N. N. Jr. and Davidson, E. A. (1967). Lysosomal hyaluronidase from rat liver II Properties. Journal of Biological Chemistry 242, 441-444. 

The levels of lysosomal hyaluronidase in subcellular fractions of eye tissues during treatment with corticosteroids have been measured. ... 

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