Experimental evidence for a 9-binding subsite of Bacillus licheniformis thermostable α-amylase.
The action pattern of Bacillus licheniformis thermostable α-amylase (BLA) was analyzed using a series of (14)C-labeled and non-labeled maltooligosaccharides from maltose (G2) to maltododecaose (G12). Maltononaose (G9) was the preferred substrate, and yielded the smallest Km=0.36 mM, the highest kcat=12.86 s(-1), and a kcat/Km value of 35.72 s(-1) mM(-1), producing maltotriose (G3) and maltohexaose (G6) as the major product pair. Maltooctaose (G8) was hydrolyzed into two pairs of products: G3 and maltopentaose (G5), and G2 and G6 with cleavage frequencies of 0.45 and 0.30, respectively. Therefore, we propose a model with nine subsites: six in the terminal non-reducing end-binding site and three at the reducing end-binding site in the binding region of BLA.
Department of Foodservice Management and Nutrition, Sangmyung University, Seoul 110-743, Republic of Korea.
Phuong Lan
PL
Tran
Department of Foodservice Management and Nutrition, Sangmyung University, Seoul 110-743, Republic of Korea.
Jin-Sil
JS
Lee
Department of Foodservice Management and Nutrition, Sangmyung University, Seoul 110-743, Republic of Korea; Department of Food Science and Biotechnology, Seoul National University, Seoul 151-742, Republic of Korea. Electronic address: parkkwanhwa@gmail.com.
Kwan-Hwa
KH
Park
D001407:Bacillus / Q000201:enzymology*; D001665:Binding Sites; D004795:Enzyme Stability; D007700:Kinetics; D008958:Models, Molecular; D009844:Oligosaccharides / Q000378:metabolism; D011487:Protein Conformation; D013696:Temperature; D000516:alpha-Amylases / Q000737:chemistry* / Q000378:metabolism*
D009844:Oligosaccharides; C021705:maltooligosaccharides; D000516:alpha-Amylases
Bacillus licheniformis thermostable α-amylase; High-performance anion exchange chromatography; Kinetic parameter; Linear maltooligosaccharides; Subsite affinity