Inhibitory effects of substrates and products on Cyclodextrin Glucanotransferase activity.

RODRIGUEZ GASTÓN, J.; SZERMAN, N.; ROSSI, A.L.; ROSSO, A.; KRYMKIEWICZ, N.; FERRAROTTI, S.

Rosario, Argentina

Congreso; SAIB XLII (Sociedad Argentina de Investigación en Bioquímica y Biología Molecular).; 2006

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Cyclodextrin glucanotransferase (CGTase) catalyses starch degradation to cyclodextrins (CD), cyclic oligosaccharides consisting of six (alpha-CD), seven (beta-CD) or eight (gamma-CD) glucose units, Besides, catalyses a coupling reaction, where the CD ring is opened and transferred to a linear dextrin in a disproportionation reaction, where part of a linear oligosaccharide is transferred to another. As a result of these reactions, CD, glucose, mallase, maltotriose and other linear maltooligosaccharides are produced. CGTase activity can be inhibited by high starch concentration and product accumulation. In this work, we study these inhibitory effects on the activity of the CGTase from Bacillus circulans DF 9R in order to optimize the CD production process. The initial reaction rate was determined as a function of the potato starch alfa, beta and gamma-CD. The optimal starch concentration was determined by measuring 2% and a substrate inhibition kinetic was observed, Furthermore, alfa, beta and gamma-CD showed a competitive inhibition kinetic on cyclation activity when the CD production from starch was measured. Low molecular weight saccharides from maltose to maltoheptaosa at 1 % w/v concentration inhibited the beta-CD production from 1 % starch. Maltose had the greatest inhibitory effect on initial reaction rate (56%) Glucose had inhibitory effect al higher concentration (above 2%).