A new cyclodextrin glucanotransferase (CGTase, EC 2.4.1.19) from an alkaliphilic halotolerant Bacillus pseudalcaliphilus 8SB was studied in respect to its gamma-cyclizing activity. An efficient conversion of a raw corn starch into only two types of cyclodextrins (beta- and gamma-CD) was achieved by the purified enzyme. Crude enzyme obtained by ultrafiltration was purified up to fivefold by starch adsorption with a recovery of 62% activity. The enzyme was a monomer with a molecular mass 71 kDa estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and native PAGE. The CGTase exhibited two pH optima, at pH 6.0 and 8.0, and was at most active at 60 A degrees C and pH 8.0. The enzyme retained more than 80% of its initial activity in a wide pH range, from 5.0 to 11.0. The CGTase was strongly inhibited by 15 mM Cu(2+), Fe(2+), Ag(+), and Zn(2+), while some metal ions, such as Ca(2+), Na(+), K(+), and Mo(7+), exerted a stimulating effect in concentration of 5 mM. The important feature of the studied CGTase was its high thermal stability: the enzyme retained almost 100% of its initial activity after 2 h of heating at 40-60 A degrees C; its half-life was 2 h at 70 A degrees C in the presence of 5 mM Ca(2+). The achieved 50.7% conversion of raw corn starch into 81.6% beta- and 18.4% gamma-CDs after 24 h enzyme reaction at 60 A degrees C and pH 8.0 makes B. pseudalcaliphilus 8SB CGTase industrially important enzyme for cyclodextrin production.