Horse mango is one of the tropical fruits that belongs from a family Anacardiaceae (mango). However, its latex is notorious for human skin due to blistering effect, suggesting the presence of strong proteolytic activity. In general, the extraction of enzymes from plants is comparatively difficult due to the presence of indigenous polyphenoloxidases and high concentration of polyphenolic compounds. During recent year, several new methods have been developed and many of the existing ones have been improved. These methods have been applied to the plant enzyme to understanding the properties of the enzyme. Therefore, this book is written for the scientists who are primarily interested in histochemical detection of protease Mangifera foetida Lour. Procedure to extract, identify and assay activity in the horse mango are also given. Furthermore, this book discusses properly how to apply Response Surface Methodology and Density Functional Theory during protease extraction. The procedures include recommended methods and all of them have been checked by the author themselves and published in Bioscience, Biotechnology and Biochemistry and Malaysian Journal of Chemistry.