GPT, also known as alanine aminotransferases (ALT1), catalyzes the reversible transamination between alanine and 2-oxoglutarate to form pyruvate and glutamate. This protein plays a key role in the intermediary metabolism of glucose and amino acids. It is widely used as an index of liver integrity or hepatocellular damage in clinical settings. Recombinant human GPT protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography.