The phenolphthalein solution used in the assay of P-Cyclodextrin is not stable and undergoes spontaneous decolorization. There is linear decrease in absorbance of phenolphthalein with time. This causes a continuous increase in error with time which is as high as 80% after one hour. A simple procedure is described in the paper to circumvent this problem allowing reproducible and reliable results to be obtained. A single reagent assay was developed by incorporating phenolphthalein in Na,C03 solution. This resulted in stable absorbance readings and increased the linearity of assay up to 200pg/ml of P-cyclodextrin. Modifizierungen der Phenolphthalein-Methode zur spektrophotometrischen Bestimmung von Beta-Cyclodextrin. Die zur Bestimmung von P-Cyclodextrin venvendete Phenolphthaleinlosung ist nicht stabil, sondern unterliegt spontaner EntWrbung. Es gibt eine lineare Verringerung der Absorption mit der Zeit. Diese bedingt eine kontinuierliche Erhohung des Fehlers mit der Zeit, die nach einer Stunde bei 80% liegen kann. Es wird ein einfaches Verfahren beschrieben, urn dieses Problem zu umgehen und reproduzierbare und zuverlassige Ergebnisse zu erhalten. Eine einzelne Reagenzanalyse wurde entwickelt unter Einbeziehung von Phenolphthalein in Na3C03Losung. Diese resultierte in stabilen Absorptionswerten und erhohte die Linearitat der Analyse bis zu 200pg/ml P-Cyclodextrin.

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A novel raw starch degrading cyclomaltodextrin glucanotransferase (CGTase; E.C. 2.4.1.19), produced by Bacillus firmus, was purified to homogeneity by ultrafiltration, affinity and gel filtration chromatography. The molecular weight of the pure protein was estimated to be 78,000 and 82,000 Da, by SDS-PAGE and gel filtration, respectively. The pure enzyme had a pH optimum in the range 5.5-8.5. It was stable over the pH range 7-11 at 10 degrees C, and at pH 7.0 at 60 degrees C. The optimum temperature for enzyme activity was 65 degrees C. In the absence of substrate, the enzyme rapidly lost its activity above 30 degrees C. K(m) and kcat for the pure enzyme were 1.21 mg/ml and 145.17 microM/mg per minute respectively, with soluble starch as the substrate. For cyclodextrin production, tapioca starch was the best substrate used when gelatinized, while wheat starch was the best substrate used when raw. This CGTase could degrade raw wheat starch very efficiently; up to 50% conversion to cyclodextrins was obtained from 150 g/l starch without using any additives. The enzyme produced alpha-, beta- and gamma-cyclodextrins in the ratio of 0.2:9.2:0.6 and 0.2:8.6:1.2 from gelatinized tapioca starch and raw wheat starch with 150 g/l concentration respectively, after 18 h incubation.

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An alkalophilicBacilhuJirmus secreting the enzyme cyclomaltodextrin glucanotransferase was isolated from soil. The enzyme attacked raw starch to produce cyclodextrins. Maximum cyclodextrins were produced from tapioca starch followed by potato and corn starch. About 49 % of tapioca starch (at 10 and 50 g/l) was converted to cyclodextrins. The main reaction products were p and y-cyclodextrins with 40 % and 8 % yield respectively. On prolonged incubation small amount of cr-cyclodextrin was also produced. The ratio of cyclodextrins was dependent on the initial substrate concentration as well as reaction time.