Enzymes Involved in the Utilization of the Galactomannan, Guar Gum, by Bacteroides Ovatus

When Bacteroides ovatus is grown on guar gum, a galactomannan, it produces an (alpha)-galactosidase (I) which is different from the (alpha)-galactosidase (II) it produces when it is grown on galactose, melibiose, raffinose or stachyose. I have purified both of these enzymes to apparent homogeneity. Both enzymes appear to be trimers and have similar pH optima (5.9-6.4 for I, 6.3-6.5 for II). However, (alpha)-galactosidase I has a pI of 5.6 and a monomeric molecular weight of 85,000 whereas (alpha)-galactosidase II has a pI of 6.9 and a monomeric molecular weight of 80,500. Alpha-galactosidase I has a lower affinity for melibiose, raffinose and stachyose (K(,m) values of 20.8 mM, 98.1 mM and 8.5 mM, respectively) than (alpha)-galactosidase II (K(,m) value of 2.3 mM, 5.9 mM and 0.3 mM, respectively). Neither enzyme was able to remove galactose residues from intact guar gum, but both were capable of removing galactose residues from guar gum which had been degraded into large fragments by mannanase.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Microbiology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

1987

Author dc:creator

• Gherardini, Frank Carlo

• Biology, Microbiology

Identifier

(UMI)AAI8711799

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/71181