In enzymology, a purine-nucleoside phosphorylase (EC 18.104.22.168) is an enzyme that catalyzes the chemical reaction: purine nucleoside + phosphate ↔ purine + alpha-D-ribose 1-phosphate. Thus, the two substrates of this enzyme are purine nucleoside and phosphate, whereas its two products are purine and alpha-D-ribose 1-phosphate. This enzyme belongs to the family of glycosyltransferases, specifically the pentosyltransferases.
PNPase; PUNPI; PUNPII
This enzyme is useful for enzymatic determination of inorganic phosphorus, 5'-nucleotidase and adenosine deaminase when coupled with xanthine oxidase and uricase.
White amorphous powder, lyophilized
Enzyme Commission Number
GradeⅢ 15U/mg-solid or more
Catalase < 20% 5'-Nucleosidase < 1.0×10⁻³% Adenosine deaminase < 1.0×10⁻³% ATPase < 1.0×10⁻²%
approx. 120 kDa
pH 6.0-9.0 (30°C, 16hr)
6.4×10⁻⁵M (Inosine), 3.2×10⁻⁴M (Pi)
below 60°C (pH 7.7, 30min)
Stable at-20°C for at least 12 months
K-Gluconate, mannitol, EDTA
p-Chloromercuribenzoate, SDS, Hg⁺⁺, Ag⁺
EC 22.214.171.124; inosine phosphorylase; PNPase; PUNPI; PUNPII; inosine-guanosine phosphorylase; nucleotide phosphatase; purine deoxynucleoside phosphorylase; purine deoxyribonucleoside phosphorylase; purine nucleoside phosphorylase; purine ribonucleoside phosphorylase; purine-nucleoside: phosphate ribosyltransferase