In this protocol, we describe one of the most commonly used PTP assays that employs the use of p-Nitrophenyl Phosphate (pNPP) as a non-proteinaceous and non-specific substrate measurement of released p-nitrophenyl to assay PTP activity. The use of pNPP is the easiest and cheapest method, but also the least selective.

Protein tyrosine phosphorylation is a reversible post-translational modification that is essential for life in eukaryotic cells. The combinatorial action of both protein tyrosine kinases and protein tyrosine phosphatases (PTPs) determines the net level of cellular tyrosine phosphorylation.

para-Nitrophenylphosphate (pNPP) is a non-proteinaceous chromogenic substrate for alkaline and acid phosphatases used in ELISA and conventional spectrophotometric assays. [1] Phosphatases catalyze the hydrolysis of pNPP liberating inorganic phosphate and the conjugate base of para -nitrophenol (pNP).

2024年9月10日 · PTP1B（Protein Tyrosine Phosphatase 1B）是一种经典的蛋白酪氨酸磷酸酶，参与调控多种重要信号通路，尤其是与胰. 岛素信号传导和代谢疾病相关。 PTP1B通过去磷酸化作用调控靶蛋白的活性，因此检测其酶活性对于研究其功能至关重. 要。 本文将详细介绍PTP1B酶活性的检测方法，并分析其功能在代谢和信号传导中的重要性。 1. PTP1B酶活性检测原理. 1.1 底物选择. PTP1B的酶活性检测依赖于使用合适的底物。 常用的人工底物是pNPP（p …

2005年1月1日 · pNPP is a colorless substrate that hydrolyzes to p -nitrophenol. The phenolate ion (p Ka of 7.2) is soluble and its bright yellow color can be monitored by absorbance at 405 nm. Because of its p Ka, the spectroscopic properties of the ion are strongest at alkaline pH.

Hydrolysis of pNPP generates p -nitrophenol and free inorganic phosphate. The amount of p -nitrophenol can be directly determined via its absorbance at 405 nm, whereas an acidic molybdate–malachite green-based reagent (e.g., Biomol Green or PiColorLock) can be used to measure released phosphate, which forms a green colored complex with the ...

As described in this unit, PTP1B activity can be determined with the small molecule substrate, p-nitrophenyl phosphate (pNPP), in which the cleavage of the phosphate results in production of p-nitrophenol (pNP) and an increase in absorbance at 405 nm.

Routinely evaluated by using one of the following kits: PTP Assay Kit 1, PTP Assay Kit 2, Ser/Thr Phosphatase Assay Kit 1, or Alkaline/Acid Phosphatase Assay Kit

Generic protein phosphatase substrates used for PTP enzymatic assays. (A) The colorimetric substrate p-nitrophenyl phosphate (pNPP). (B) The fluorogenic substrates...

Sigma-Aldrich P7998 用于ELISA的碱性磷酸酶黄色（pNPP）液体底物系统