Triggered enzymatic degradation of a water-soluble polymer solution using a novel inhibitor.
Controlled enzymatic degradation of solutions of guar galactomannan, a naturally occurring polysaccharide, offers a powerful tool to enhance its usage in a variety of applications. In this study, we use viscometry to investigate the use of tris(hydroxymethyl)aminomethane (Tris) as a reversible, pH-dependent inhibitor to control the degradation of guar galactomannan by Aspergillus niger beta-mannanase. Viscosity measurements of pH 9 guar solutions containing 25 mM Tris show no reduction in the viscosity when treated with beta-mannanase. In contrast, samples containing no Tris show significant reduction in viscosity within an hour. Samples maintained at a pH of 9 in the presence of Tris for several hours show no change in viscosity; however, reduction of the pH of the sample to 4 initiates enzymatic degradation of the guar solution resulting in a rapid reduction in solution viscosity. This reversible, pH-dependent inhibition is possibly a result of the protonation state of Tris as well as key amino acids in the active site.
Burke
M D
MD
Department of Chemical Engineering, North Carolina State University, Raleigh, North Carolina 27695-7905, USA.
Khan
S A
SA
D001234:Aspergillus niger / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D005685:Galactans / Q000737:chemistry*; D005690:Galactose / Q000031:analogs & derivatives; D006863:Hydrogen-Ion Concentration; D008351:Mannans / Q000737:chemistry*; D008361:Mannosidases / Q000037:antagonists & inhibitors / Q000737:chemistry; D053149:Plant Gums; D012212:Rheology; D014325:Tromethamine / Q000737:chemistry / Q000494:pharmacology*; D014783:Viscosity; D044902:beta-Mannosidase
D004791:Enzyme Inhibitors; D005685:Galactans; D008351:Mannans; D053149:Plant Gums; D014325:Tromethamine; C012990:galactomannan; C007894:guar gum; D008361:Mannosidases; D044902:beta-Mannosidase; D005690:Galactose