Abstract: Water-soluble microcapsules using a water-containing hydrophilic substance as a core material and at least one member selected from the group consisting of polyvinyl alcohol and modified polyvinyl alcohols as a coating material are stably retained in a concentrated aqeuous solution and are dissolved in water or a dilute aqueous solution.

Abstract: Alkaline protease API-21 having the following physicochemical properties:(1) Activity: Hydrolyzes casein under alkaline conditions, optimum pH range is 10 to 11, and has optimum temperature range for activity of 45.degree. C. to 50.degree. C.;(2) Stability: No decrease in enzymatic activity observed up to 40.degree. C. upon heating without substrated for 10 minutes at a pH of 10, but 90% or more decrease of enzymatic activity observed at 50.degree. C. for 10 minutes at a pH of 10. Deactivation occurs at 50.degree. C. for 10 minutes at a pH of 8 and complete deactivation substantially occurs at 60.degree. C. for 10 minutes at a pH of 8. The protease is stable under alkaline conditions, especially within a pH range of 7 to 11.5, and is stable against freezing and freeze-drying; and(3) Enzyme molecule: The protease is protein having a molecular weight of about 22000 as estimated by a gel filtration method, an isoelectric point of 7.