. "Isolated from cells and culture medium of the thermophilic archae Sulfolobus acidocaldarius, optimum digestion at pH 2 and 90 degrees Celsius, inhibited by pepstatin." . "Another thermostable bacterial endopeptidase has been isolated from Bacillus sp., but this is not inhibited by pepstatin." . "Belongs to peptidase family A5." . . . "Thermopsin" . . "Specificity similar to pepsin A, prefers bulky hydrophobic side-chains on either side of the scissible bond." . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .