Application

Alkaline phosphatase is used for conjugation to antibodies and other proteins for ELISA, Western blotting, and histochemical detection. It is routinely used to dephosphorylate proteins and nucleic acids. It may be used for protein labeling when high sensitivity is required. Alkaline phosphatase may be also be used to dephosphorylate the 5′-termini of DNA or RNA to prevent self-ligation. DNA or RNA can also be tagged with radiolabeled phosphate (via T4 polynucleotide kinase) after dephosphorylation with alkaline phosphatase.

Biochem/physiol Actions

Alkaline phosphatase dephosphorylates proteins and nucleic acids. Human placental alkaline phosphatase (PLAP) has an unique residue, Glu-429. It is an allosteric enzyme that is uncompetitively inhibited by L-Phe, L-Trp, and L-Leu. PLAP is post-translationally modified. Phosphatidylinositol-specific phospholipase C may be involved in the release of PLAP. PLAP may have a role in cell division and may be involved in the transfer of maternal IgG to the fetus.

Unit Definition

One unit will hydrolyze 1.0 umole of P-Nitrophenyl Phosphate per minute at pH 10.4 at 37 Deg C.