Purification and characterization of a neutral serine protease from non-sulfur purple photosynthetic bacterium
Moon-Sik Hyun; Shin-ichi Okuda; Kazuo Izaki
Current Microbiology 18(6): 379-383
ISSN/ISBN: 0343-8651 DOI: 10.1007/bf01571132
A neutral serine protease was purified as a homogeneous protein from the culture broth of photosynthetic bacterium T-20 by sequential chromatographies on columns of DEAE-cellulose. Toyopearl HW 55F, hydroxyapatite, and CM-cellulose. The molecular weight was estimated to be approximately 44,000 by SDS-PAGE, while the value of approximately 80,000 was obtained when the Hedrick-Smith method was used; this suggested that the enzyme consists of two identical subunits. The isoelectric point was determined to be 6.3 by isoelectric focusing. The enzyme had a pH optimum at 7.8. Maximal enzyme activity was detected at 50.degree.C, and the activity was stable up to 50.degree.C for 5 min at pH 7.0-7.2.