A-Amylase barley

Enzyme induction a-amylase, barley aleurone Promotes ABA- R-1... 

Theophylline Inhibits 3, 5 - a-Amylase Barley Duffus and Dufftis... 

Amylase occurs in many plants, such as barley, wheat, rye, soy beans, and potatoes, where it is generally accompanied by some a-amylase. [ -Amylase initiates hydrolysis at the nonreducing end of an amylose or amylopectin chain, and removes maltose units successively until the reducing end of the molecule is encountered in amylose or a branch is met in amylopectin. ( -Amylase is used commercially in the preparation of maltose symps. After P-amylase hydrolysis of amylopectin there remains a P-amylase limit dextrin. ( -Amylase has been used as a probe of the fine stmcture of amylopectin (43-46). 

Jacobsen, J.V., Hanson, A.D. Chandler, P.C. (1986). Water stress enhances expression of an a-amylase gene in barley leaves. Plant Physiology, 80, 350-9. 

Drought also has a profound effect on protein synthesis. In many plant tissues, a reduced water potential causes a reduction of total protein synthesis and a rapid dissociation of polyribosomes. The latter has been shown not to be the consequence of increase in ribonuclease activity (Hsiao, 1973 Dhindsa Bewley, 1976). For a specific protein, Jacobsen, Hanson Chandler (1986) have shown in barley leaves that water stress enhances the synthesis of one of the a-amylase isozymes. Using a cDNA probe they found that water-stressed leaves contained much more a-amylase mRNA than unstressed plants. 

Hanson, A.D. Jacobsen, J.V. (1984). Control of lactate dehydrogenase, lactate glycolysis and a-amylase of O2 deficit in barley aleurone layers. Plant Physiology, 75, 566-72. 

Aprotinin Maize ubiquitin promoter/ pinll terminator Maize ubiquitin 5 intron, barley a-amylase LP Extracellular matrix of embryo (maize seeds) In T5 0.35% of extractable seed proteins 16... 

Several plant defensins have also been found to be inhibitors of various enzymes in plant pests. The plant defensins Slctl, SIo 2, and SIa3 were the first plant defensins where inhibition of a-amylase was shown at low concentration whereas purothionins inhibited a-amylase activity only at high concentrations. Blal and BIa2 isolated from barley are two more representatives of proteinaceous a-amylase inhibitors in the plant defensin family. ... 

There are also some peptides exhibiting a-amylase inhibitory potency. The plant defensins Slal, SIa2, and SIa3 from Sorghum bicolor and Blal and BIa2 from barley have been mentioned before. The knottin-type a-amylase inhibitor peptide AAI from Amaranthus hypochondtiacus is the smallest peptide ct-amylase inhibitor known to date. ... 

Contacts with the catalytic residues, in combination with hydrophobic interactions, are also observed in the complex of an insect a-amylase with the Ragi bifunctional a-amylase/trypsin inhibitor (RBI) [174]. Conversely, the mechanism of inhibition of barley a-amylase by the barley a-amylase/subtilisin inhibitor (BASI) did not involve direct contact between inhibitor residues and the catalytic site [175]. The inhibitor sterically blocks the catalytic site, but does not extend into it. A cavity is created, which is occupied by a calcium ion coordinated by water-mediated interactions with the catalytic residues. 

Varner, J., Ram Chandra, G., Chrispeels, M.J. (1965). Gibberellic-acid controlled synthesis of a-amylase in barley endosperm. J. Cell. Comp. Physiol. 65, 55-67. 

Fig. 3. Translation products of barley aleurone layer mRNAs. Lanes 1-4, total products from layers treated in water (control), 1 jxm ABA, 1 pM GA3, or both hormones, respectively. The rab 6 protein is marked with an arrow. Lanes 5-8, immunoprecipitation of a-amylase (upper bands) and the a-amylase/subtilisin inhibitor (lower bands) from the translation products shown in lanes 1-4. mRNA extraction, translation and immunoprecipitation were performed as previously described (Mundy etal., 1986).

Jacobsen, J.V. Beach, L.R. (1985). Control of transcription of a-amylase and rRNA genes in barley aleurone protoplasts by gibberellin and abscisic acid. Nature 316, 275-7. 

Khursheed, B. Rogers, J.C. (1988). Barley a-amylase genes. Quantitative comparison of steady-state mRNA levels from individual members of the two different families expressed in aleurone cells. Journal of Biological Chemistry 263, 18953-60. 

Khursheed, B. Rogers, J. (1989). Barley a-amylase genes and the thiol protease gene Aleurain Use of a single poly (A) addition signal associated with a conserved pentanucleotide at the cleavage site. Proceedings of the National Academy of Sciences (USA) 86, 3987-91. 

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