Catalytic properties and stability of three common variants of placental alkaline phosphatase

✍ Scribed by Per Åke Holmgren; Torgny Stigbrand

• Publisher: Springer
• Year: 1978
• Tongue: English
• Weight: 430 KB
• Volume: 16
• Category: Article
• ISSN: 0006-2928
• DOI: 10.1007/bf00484209

✦ Synopsis

Three placental alkaline phosphatases purified to homogeneity, i.e., the F, I, and S variants, were investigated for catalytic and stability properties. All three forms of the enzyme were found to have almost identical pH optima (10.7--10.8), similar sensitivity to the uncompetitive inhibitors L-phenylalanine (70%) and L-leucine (30%), and identical Km values against p-nitrophenylphosphate, beta-glycerophosphate, and alpha-naphthylphosphate. Significant differences among the three types were observed in thermal stability. The F variant was found to be most stable and the I variant most labile at 79 C. At 70 C all three forms were stable.