Submitted to: American Society of Plant Biologists Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/2003
Publication Date: 8/1/2003
Citation: CLARK, S.E., MUSLIN, E.H., HENSON, C.A. THE EFFECT OF ADDING AND REMOVING N-GLUCOSYLATION SITES ON THERMOSTABILITY OF BARLEY ALPHA-GLUCOSIDASE. Plant Biology. 2003. 75. Abs. 244.
Technical Abstract: Alpha-glucosidase is one of the enzymes involved in the starch degradation pathway that produces sugars for the growing embryo in barley (Hordeum vulgare L.) seeds. The hydrolysis of starch to various sugars is also an important step in the alcohol production industries (e.g. beer and ethanol fuel production). The industrial process to produce fermentable sugars occurs at temperatures from 60-75C. Unfortunately, alpha-glucosidase is one of the most thermolabile of the starch hydrolyzing enzymes in barley seeds so its contribution to the production of fermentable sugars at these temperatures is limited. To identify amino acids in barley alpha-glucosidase that may be responsible for the observed thermolability, we compared its deduced amino acid sequence to that of the sugarbeet alpha-glucosidase, which we showed to be more thermostable (Muslin, Clark and Henson, 2002). N-glucosylation sites that were in the barley sequence and not in the sugarbeet sequence and vice versa were targeted for mutagenesis. One mutation that inserted a N-glycosylation recognition sequence towards the C-terminus of barley alpha-glucosidase resulted in a 7C increase in the enzyme's thermostability.