Protein profiling of Orthosiphon stamineus

Abstract

Orthosiphon stamineus (cat whiskers) is a medicinal herb belonging to the family of Lamiaceae, where the leaves are commonly used as herbal tea known as “Java tea”. It is used as a diuretic agent and for the treatment of heat rheumatism. Currently there is no protein profile data available for this important plant species. This study focus on the optimization of total protein extraction by employing four different methods of extraction protocols; QB buffer, Phenol/SDS with three prewashed steps, Phenol/SDS without prewashed steps and Sigma protein extraction kit with the aim of determining the best protein extraction method, protein pattern of the two varieties of O.stamineus (white and purple flower) and bioinformatics analysis to identify the proteins. Overall, Phenol/SDS with three prewashed steps result in a better protein quality and pattern of separation for both plant varieties.A total of 104 functional proteins were identified with each containing at least one unique peptide. Among the identified proteins, Rubisco activase and Triosephosphate isomerase corresponds to the chloroplastic protein of photosynthesis/carbohydrate metabolism while Phosphoglycerate kinase and Glyceraldehyde are cytosolic enzymes of glycolysis pathway which were found to be major housekeeping proteins in a leaf tissue. The result of this study will provide an insight for advanced pharmaceutical research and a baseline information for further proteomics work on O. stamineus and similar plant species.