A kinetic model for the hydrolysis and synthesis of maltose, isomaltose, and maltotriose by glucoamylase

✍ Scribed by V. Beschkov; A. Marc; J. M. Engasser

• Publisher: John Wiley and Sons
• Year: 1984
• Tongue: English
• Weight: 351 KB
• Volume: 26
• Category: Article
• ISSN: 0006-3592
• DOI: 10.1002/bit.260260106

✦ Synopsis

Kinetic results on the glucoamylase-catalysed hydrolysis of maltose and maltotriose, and glucose polymerization into maltose and isomaltose up to 450 g/L total sugar concentration are presented. Whereas the enzyme has a faster hydrolytic and synthetic activity on ~(1'4) than on a-(I -6) linkages, at equilibrium, on the contrary, the isomaltose level which represents 15% (wlw) of the total sugar concentration at the highest investigated concentrations is much higher than the corresponding maltose level. Under a wide range of initial conditions, experimental results are adequately described by a new kinetic model with simple first-and second-order, or Michaeliantype, rate expressions for the reversible hydrolysis of maltotriose, maltose, and isomaltose. The model also accounts for the inhibition of hydrolysis by glucose, but does not consider the concentration of water which, under the present conditions, was not found kinetically limiting.

Operating Conditions

Kinetic experiments were carried out in a thermostated stirred glass reactor at 4OoC and pH 4.6 (acetate buffer).