Pullulanase type I (PulA) is a debranching enzyme that specifically cleaves α-1,6-glycosidic linkages in pullulan. Pullulan has not only diverse applications in food industry but also has immune-stimulatory effects on B and T cells, and found to enhance the production of various anti-inflammatory cytokines in human. Moreover, pullulan has been suggested as a possible anti-cancer drug delivery agent without adjuvant due to its unique structure. The process of pullulan degradation is unresolved due to imprecise pullulanase structural characteristics. Therefore, the present study aimed to understand the structural and functional characteristics of pullulanase enzyme from Geobacillus thermopakistaniensis MAS1 strain using various computational approaches. The physio-chemical topographies and secondary structure of GT_PulA were explored using ProPram, InterPro and SMART. Various tools like I-TASSER, ModRefiner, RAMPAGE, PROCHECK and MOE 2009.10 were used to construct and verify the 3D structural model. The structural elucidation confirmed the significant domains, i.e., CBM48, CBM2, and TIM barrel having catalytically active residues, and conserved region YNGWDP. CBM2 domain along with TIM barrel has a capacity to bind different ligands and proved favorable for multiple substrate catalyses. These structural properties can have a potential effect on enhancing enzymatic activity of GT_PulA enzyme.

中文翻译：

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热巴氏芽孢杆菌的1型支链淀粉酶（PulA）的结构和功能分析。

I型支链淀粉酶（PulA）是一种脱支酶，可特异性切割支链淀粉中的α-1,6-糖苷键。普鲁兰聚糖不仅在食品工业中具有多种用途，而且对B细胞和T细胞具有免疫刺激作用，并被发现可以增强人类各种抗炎细胞因子的产生。此外，由于其独特的结构，已提出支链淀粉作为无佐剂的可能的抗癌药物递送剂。由于不精确的支链淀粉酶的结构特征，支链淀粉降解的过程无法解决。因此，本研究旨在通过多种计算方法来了解热巴氏芽孢杆菌MAS1菌株的支链淀粉酶的结构和功能特性。使用ProPram探索了GT_PulA的理化拓扑结构和二级结构，InterPro和SMART。使用I-TASSER，ModRefiner，RAMPAGE，PROCHECK和MOE 2009.10等各种工具来构建和验证3D结构模型。结构解析证实了重要的结构域，即具有催化活性残基的CBM48，CBM2和TIM桶，以及保守区YNGWDP。CBM2结构域与TIM圆柱体一起具有结合不同配体的能力，并被证明对多种底物催化是有利的。这些结构性质可能对增强GT_PulA酶的酶活性具有潜在的影响。保守区YNGWDP。CBM2结构域与TIM桶一起具有结合不同配体的能力，并被证明对多种底物催化有利。这些结构性质可能对增强GT_PulA酶的酶活性具有潜在的影响。保守区YNGWDP。CBM2结构域与TIM桶一起具有结合不同配体的能力，并被证明对多种底物催化有利。这些结构性质可能对增强GT_PulA酶的酶活性具有潜在的影响。