Ulpiyana Ayra, Frima Fina Khaerunnisa, Annisa Diandra Sekar, Tan Josephine Claudia, Puspasari Fernita, Aditama Reza, Natalia Dessy
Biochemistry and Biomolecular Engineering Research Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesa 10 Bandung, 40132, Indonesia.
Department of Chemistry, Faculty of Science, Institut Teknologi Sumatera, Jalan Terusan Ryacudu, Way Hui, Jati Agung, Lampung, Lampung Selatan, 35365, Indonesia.
Heliyon. 2024 Jul 5;10(14):e33667. doi: 10.1016/j.heliyon.2024.e33667. eCollection 2024 Jul 30.
BaqA is a raw starch degrading α-amylase produced by the marine bacterium MKSC 6.2, associated with soft corals. This α-amylase belongs to a new subfamily Glycoside Hydrolases (GH) 13_45 which has several unique characteristics, namely, a pair of tryptophan residues Trp201 and Trp202, a distinct LPDIx signature in the Conserved Sequence Region-V (CSR-V), and an elongated C-terminus containing five aromatic residues. The research aims to investigate physicochemical, kinetics, and biochemical properties of BaqA. In this study, the full-length enzyme (BaqA) and a truncated form of BaqA (designated as BaqAΔC), lacking the C-terminal 34 amino acids were constructed and expressed in ArcticExpress (DE3). BaqA formed inclusion bodies, while BaqAΔC was produced as a soluble protein. Purified and refolded BaqA exhibited a catalytic efficiency ( / ) of 53.1 ± 6.3 mL mg s at 40 °C and pH 7.5, whereas the purified BaqAΔC displayed / of 11.4 ± 1.3 mL mg s under the optimum condition of 50 °C and pH 6.5. Moreover, BaqAΔC showed a slight reduction in the binding affinity towards sago granules. Interestingly, BaqAΔC displayed robust stability and halotolerant properties compared to BaqA. BaqAΔC maintained 50 % amylolytic activity for up to 6 h, whereas BaqA lost over 50 % of its activity within 90 min. Furthermore, BaqAΔC showed a remarkable increase in amylolytic activity upon the addition of NaCl, with an optimum concentration of 0.5 M. Even at a high salt concentration (1.5 M NaCl), BaqAΔC retained over 50 % of its residual activity. Taken together, its solubility, amylolytic activity, stability, ability to degrade raw starch, and moderate halotolerance make BaqAΔC a promising candidate for various starch processing industries.
BaqA是一种由与软珊瑚相关的海洋细菌MKSC 6.2产生的可降解生淀粉的α-淀粉酶。这种α-淀粉酶属于糖苷水解酶(GH)13_45新亚家族,具有几个独特的特征,即一对色氨酸残基Trp201和Trp202、保守序列区域-V(CSR-V)中独特的LPDIx特征以及包含五个芳香族残基的延长C末端。该研究旨在研究BaqA的物理化学、动力学和生化特性。在本研究中,构建了全长酶(BaqA)和缺少C末端34个氨基酸的BaqA截短形式(命名为BaqAΔC),并在北极快车(ArcticExpress)(DE3)中进行表达。BaqA形成包涵体,而BaqAΔC作为可溶性蛋白产生。纯化并复性后的BaqA在40°C和pH 7.5时的催化效率(kcat/Km)为53.1±6.3 mL mg-1 s-1,而纯化后的BaqAΔC在50°C和pH 6.5的最佳条件下显示出11.4±1.3 mL mg-1 s-1的kcat/Km。此外,BaqAΔC对西米颗粒的结合亲和力略有降低。有趣的是,与BaqA相比,BaqAΔC表现出更强的稳定性和耐盐性。BaqAΔC在长达6小时内保持50%的淀粉分解活性,而BaqA在90分钟内失去超过50%的活性。此外,加入NaCl后,BaqAΔC的淀粉分解活性显著增加,最佳浓度为0.5 M。即使在高盐浓度(1.5 M NaCl)下,BaqAΔC仍保留超过50%的残余活性。综上所述,BaqAΔC的溶解性、淀粉分解活性、稳定性、降解生淀粉的能力和适度的耐盐性使其成为各种淀粉加工行业的有前途的候选者。