Identification of industrial detergent enzymes by SDS-PAGE and MALDI-TOF mass spectrometry

Abstract

SDS-PAGE and MALDI-TOF mass spectrometry have been developed for the first time to identify the main types of enzymes used in laundry detergents, including protease, lipase, cellulase, α-amylase, and mannanase. For this purpose, preliminary experiments were performed on the standard enzymes and after optimizing the conditions and evaluating the efficiency of the method in the mixture of enzymes, granular enzymes were investigated by mass spectrometry. The main characteristic bands of protease, lipase, mannanase, cellulase, and α-amylase on gel were detected by MALDI-TOF mass spectrometry at approximately 27, 31, 33, 36, and 54 kDa. Also, these characteristic bands were detected successfully in multi-mixtures of enzymes, as well as multi-enzyme granules. Furthermore, the main bands of each enzyme were collected, digested with trypsin, recorded, and detected using MASCOT software. Score values for standard enzymes of protease, lipase, α-amylase, and granular α-amylase were obtained as 102, 138, 153, and 90, respectively, and their taxonomy was detected successfully. Finally, the suitability of the SDS-PAGE method for routine analysis in the detergent industry was evaluated with fortified powder detergent samples. Based on the obtained results, the characteristic bands with a good resolution were found in the mass ranges of 25, 25–35, 35, 35–48, and 48–63 kDa, which confirms the presence of protease, mannanase, lipase, cellulase, and α-amylase, respectively, in the fortified detergent samples. Therefore, the SDS-PAGE method can be used as an alternative to the traditional method for quality control of granular enzymes and manufactured detergents, with various claims. In addition, MALDI-TOF mass spectrometry and in-gel digestion can be utilized to confirm the molecular weight and determine their taxonomy.