Through (NH_4)_2SO_4 partial precipitation, DEAE-cellulose chromatography and phospho-cellulose chromatography, PTPP can be purified partially from human erythrocytes cytosol with a 5.7% yield and a 1075-fold enrichment. Using ̄(32)P-Tyr-poly(G_4:T) as substrate, the apparent Km of the enzyme is 0. 5-0. 8μmol/L, and the optimum temperature and optimum pH are 37-40℃ and 7.0-7. 4, respectively. The PTPP activities can be inhibited by bivalent cations such as Zn ̄(2+) etc. and many anions(group) such as VO ̄(3-)_4 etc. EDTA,glycerol, DTT, mercaptoethanol etc. can stimulate the PTPP activities; Fluoride, tartrate,some inhibitor to acidic or alkaline phosphatases, have little effect on the PTPP activities. In addition, some proteins, nucleotides, amino acids, anti-tumour agents etc. have various effects on the PTPP activities. Especially, some PKs (protein kinases) and PPs (protein phosphatases) may regulate the PTPP activities, in vitro.
Zhu,Mao-xiang;Wu,Guo-li.
Research for Phosphotyrosyl Protein Phosphatases (PTPPs) of Human Erythrocytes Ⅱ· Purification and Characterization of Cytosolic PTPP[J]. Chinese Journal of Biochemistry and Molecular Biology, 1994, 10(02): 174-179