Effects of glycosidase treatment on factor V procoagulant activity and inactivation by APC. (A) Procoagulant activity of purified factor V was determined using a PT clotting assay with factor V-deficient plasma after preincubation of factor V with neuraminidase (▴), N-glycanase (▾), O-glycanase (♦), or buffer (○) or with a mixture of neuraminidase and N-glycanase (•) for the indicated time periods. (B) APC resistance tests were performed according to the Materials and Methods using the glycosidase-treated purified factor V samples as described in (A).