Vertebrate hyaluronidase

Further Analyses of the Vertebrate Hyaluronidase Enzyme Family... 

The vertebrate hyaluronidases, previously neglected enzymes [185], are all endo-P-A-acetylhexosaminidases employing substrate hydrolysis as their mechanism of action. These hydrolases have, until recently, been difficult to assay. Turbidometric and... 

The first vertebrate hyaluronidase activity to be identified was derived from a testicular extract [188], active at neutral pH. A similar enzyme, but active at acidic pH, was later documented in human serum [189]. Another thirty years passed before sufficient purification was achieved for sequence analysis [172]. 

Jedrzejas, M. J. and Stem, R. (2005). Stmctures of vertebrate hyaluronidases and their unique enzymatic mechanism of hydrolysis. Proteins 61, 227-238. 

A vertebrate homologue of the cell cycle control protein CDC37 was recently cloned and found to be an hyaladherin,62 as was a protein that copurified with the splicing factor SF2.63 An intracellular form of the HA receptor RHAMM was demonstrated to regulate erk kinase activity. Changes in function of these intracellular, depending on whether or not they have HA molecules attached, confers another layer of complexity dependent on intracellular hyaluronidase enzymes. 

Fiszer-Szafarz, B., Szafarz, D., and Vannier, P., Polymorphism of hyaluronidase in serum from man, various mouse strains and other vertebrate species revealed by electrophoresis, Biol Cell., 68, 95, 1990. 

The hyaluronidase enzymes from vertebrate tissues occur in a number of isoforms. The biological significance of these isoforms is not known, nor is it understood how they participate in the catabolic scheme. 

Three of the hyaluronidases from vertebrates are GPI-anchored, namely Hyal2, Hyal4, and PH-20. Processed forms of Hyal2 and PH-20 have been detected, with removal of the GPI-membrane anchor, thus releasing the enzyme and generating a freely soluble form. This has been well documented for PH-20 [191,192]. Splice variants of Hyall and Hyal3 mRNAs have also been documented... 

There are hyaluronidases that function as endo-(3-glucuronidases that cleave the (1 3)-P glycosidic bonds. However, no sequence data on these enzymes is yet available. These enzymes are characteristic of annelids such as leeches e.g., Herudo medicinalis [196-198], and certain crustaceans [199]. They utilize the hydrolysis mechanism, and thus resemble the vertebrate enzymes more closely than the prokaryotic hyaluronidases. 

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