Amino acid substitutions of the limit dextrinase gene in barley are associated with enzyme thermostability

The expression of the gene associated with β-glucan content, β-amylase and limit dextrinase synthesis as affected by post-heading heat stress in barley

“…βamylase and limit dextrinase are key important enzymes involved in complete decomposition of starch into sugars, and low activities of both enzymes cause low malt extract, which is directly related to beer quality and economic profits of malt or beer producers [8]. β-glucan content, β-amylase and limit dextrinase activities in barley grains are controlled by both genetic and environmental factors [10,[25][26]. The influence of environmental conditions on these malt quality traits have been intensively investigated [10,[26][27][28].…”

“…β-glucan content, β-amylase and limit dextrinase activities in barley grains are controlled by both genetic and environmental factors [10,[25][26]. The influence of environmental conditions on these malt quality traits have been intensively investigated [10,[26][27][28]. In a previous study, we investigated the impact of one-week heat stress (32/26℃, day/night) initiating from the 7th (HT7) and 14th (HT14) days after heading on some grain and malt quality traits of two barley varieties.…”

Review: Amylopectin synthesis and hydrolysis – Understanding isoamylase and limit dextrinase and their impact on starch structure on barley ( Hordeum vulgare ) quality

“…Both the two 2-rowed varieties had the highest level of amylase and one of these, Harrington, had the highest level of LD (Lapitan, Hess et al 2009). Harrington has the low thermostable allele (Yang, Westcott et al 2009), however in any low temperature mashing, the slow ramping could be conducive for optimal activity of LD. But the major drawback with this mashing style is the low temperature hasn't provided conditions for starch to gelatinise, hence there is no starch degrading enzyme activity.…”

“…As the Isa1 is responsible for hydrolysising the α-1,6 branches from amylopectin, changes in amylopectin structure have been identified in wild types where there was a deletion in the Isa1 gene (Burton, Jenner et al 2002). The limit dextrinase gene LD form also has single point mutations resulting in an amino acid substitution giving increased thermostability in an in-vitro assay although this has yet to be confirmed under mashing conditions in the mash (Yang, Westcott et al 2009). Figure 4 shows the amino acid sequence from studies sequencing the limit dextrinase gene.…”

Barley and Wheat Share the Same Gene Controlling the Short Basic Vegetative Period

“…Ltd. Molecular markers with size differences between Mona and Turk were run on 6-8% PAGE gels. The single nucleotide polymorphic (SNP) markers were detected on SSCP gels using a previously described procedure (Yang et al 2009) and was optimized with a 12% polyacrylamide gel (acrylamide/bisacrylamide ratio of 37.5:1) in 0.5×Tris-borate-ethylenediaminetetraacetic acid and run at room temperature for 22-32 h.…”