Alpha-l-iduronidase and arylsulfatase B in dried blood spots on filter paper: Biochemical parameters and time stability

The goal of this study was to assess the biochemical parameters of the enzymes α-l-iduronidase (IDUA) and arylsulfatase B (ASB), which are deficient in mucopolysaccharidosis (MPS) I and VI, respectively, in dried blood spot (DBS) samples impregnated on filter paper. The optimal pH, Km, and Vmax of IDUA and ASB in DBS are hereby presented. After these analyses, the reference values for the activities of these enzymes in DBS with cutoff of 3.65nmol/h/mL for IDUA and 6.80nmol/h/mL for ASB were established. The research also showed that the stability (21days) of the IDUA activity is lower than ASB, which maintained its enzymatic activity stable up until 60days of analysis, after impregnating the filter paper with blood. Currently, DBS ensures important advantages in handling storage and transportation of samples with respect to neonatal screening programs. This study contributes to characterizing and differentiating the biochemistry of deficient enzymes in MPSs I and VI of DBS samples. •Enzimatic activity determination on dried blood spots (DBS) on filter paper is well known established.•The cutoff activity of IDUA enzyme in DBS was 3.65nmol/h/mL.•The cutoff activity of ASB enzyme in DBS was 6.80nmol/h/mL.•The stability of the IDUA activity is lower than ASB activity.•Standardized biochemical parameters for DBS samples can provide confident results in the investigation of MPS.