Hyaluronidase1 (HYAL1) is a hydrolytic enzyme that degrades hyaluronic acid (HA) and has three predicted N-glycosylation sites at Asn99, Asn216, and Asn350. In this report, we show the functional significance of N-glycosylation on HYAL1 functions. Using mass spectrometry, we demonstrated that HYAL1 was N-glycosylated at the three asparagine residues. N-glycosylation of HYAL1 is important for secretion of HYAL1, as demonstrated by site-directed mutation. Moreover, a defect of N-glycosylation attenuated the enzymatic activity of HYAL1. Thus, HYAL1 is N-glycosylated at the three asparagine residues, and its secretion and enzymatic activity are regulated by N-glycosylation.
