Purification and biochemical characterization of two detergent-stable serine alkaline proteases from Streptomyces sp. strain AH4

Abstract

Streptomyces sp. strain AH4 exhibited a high ability to produce two extracellular proteases when cultured on a yeast malt-extract (ISP2)-casein-based medium. Pure proteins were obtained after heat treatment (30 min at 70 °C) and ammonium sulphate fractionation (30-60 %), followed by size exclusion HPLC column. Matrix assisted laser desorption ionization-time of flight mass spectrometry analysis revealed that the purified enzymes (named SAPS-P1 and SAPS-P2) were monomers with molecular masses of 36,417.13 and 21,099.10 Da, respectively. Their identified N-terminal amino acid displayed high homologies with those of Streptomyces proteases. While SAPS-P1 was optimally active at pH 12.0 and 70 °C, SAPS-P2 showed optimum activity at pH 10.0 and 60 °C. Both enzymes were completely stable within a wide range of temperature (45-75 °C) and pH (8.0-11.5). They were noted to be completely inhibited by phenylmethanesulfonyl fluoride and diisopropyl fluorophosphates, which confirmed their belonging to the serine proteases family. Compared to SAPS-P2, SAPS-P1 showed high thermostability and excellent stability towards bleaching, denaturing, and oxidizing agents. Both enzymes displayed marked stability and compatibility with a wide range of commercial laundry detergents and significant catalytic efficiencies compared to Subtilisin Carlsberg and Protease SG-XIV. Overall, the results indicated that SAPS-P1 and SAPS-P2 can be considered as potential promising candidates for future application as bioadditives in detergent formulations.

A novel organic solvent- and detergent-stable serine alkaline protease from Trametes cingulata strain CTM10101

“…The proteolytic activity present in the laundry detergent solution was evaluated by the method of Boulkour Touioui et al [29] using N,N-dimethylated casein (DMC) as a substrate.…”

Identification of a New Serine Alkaline Peptidase from the Moderately Halophilic Virgibacillus natechei sp. nov., Strain FarDT and its Application as Bioadditive for Peptide Synthesis and Laundry Detergent Formulations

“…Peptidase activity present in the laundry detergent solution was determined through the method proposed by Boulkour Touioui et al [26] which used the N , N -dimethylated casein (DMC) as a substrate and 2,4,6-trinitrobenzene sulfonic acid (TNBSA) as a colour indicator. One unit of protease activity was defined as the amount of enzyme required to catalyze the cleavage of 1 µ mole of peptide bond from DMC per minute under the experimental conditions used.…”

Purification and biochemical characterization of a novel thermostable protease from the oyster mushroom Pleurotus sajor-caju strain CTM10057 with industrial interest

“…The SPPS activity, in detergent solution, was measured at 450 nm using N , N -dimethylated casein as substrate at 40 °C and pH 9 as reported elsewhere [29].…”