Structure and Function Insight of the α-Glucosidase QsGH13 From Qipengyuania seohaensis sp. SW-135

Abstract

The α-glucosidases play indispensable roles in the metabolic mechanism of organism, prevention, and treatment of the disease, and sugar hydrolysis, and are widely used in chemical synthesis, clinical diagnosis, and other fields. However, improving their catalytic efficiency and production to meet commercial demand remains a huge challenge. Here we detected a novel GH13 family α-glucosidase, QsGH13, from the deep-sea bacterium Qipengyuania seohaensis sp. SW-135. QsGH13 is highly substrate specific and only hydrolyzes sugars containing alpha-1,4 glucoside bonds. For example, its enzymatic activity for p-nitrophenyl-α-D-glucopyranoside was 25.41 U/mg, and the Km value was 0.2952 ± 0.0322 mM. The biochemical results showed that the optimum temperature of QsGH13 is 45°C, the optimum pH is 10.0, and it has excellent biological characteristics such as alkali resistance and salt resistance. The crystal structure of QsGH13 was resolved with a resolution of 2.2 Å, where QsGH13 is composed of a typical TIM barrel catalytic domain A, a loop-rich domain B, and a conserved domain C. QsGH13 crystal belonged to the monoclinic space group P212121, with unit-cell parameters a = 58.816 Å, b = 129.920 Å, c = 161.307 Å, α = γ = β = 90°, which contains two monomers per asymmetric unit. The β → α loop 4 of QsGH13 was located above catalytic pocket. Typical catalytic triad residues Glu202, Asp266, and Glu329 were found in QsGH13. The biochemical properties and structural analysis of QsGH13 have greatly improved our understanding of the catalytic mechanism of GH13 family. This study provides new ideas to broaden the application of α-glucosidase in alcohol fermentation, glycolysis, and other industries.

Metabolomics‐based pharmaceutical evaluation of different parts of Swertia chirayita (Roxb.) Buch.‐Ham. ex C.B. Clarke from the western Himalayas

“…Alpha-glucosidases and pancreatic alpha-amylases are the enzymes involved in the digestion of dietary carbohydrates and hence, are major determinants of postprandial blood glucose levels [10]. These enzymes act on polysaccharides at α−1,4-glycosidic bonds, breaking which liberates α-D-glucose [79,80]. Hence, inhibition of alpha-glucosidases and pancreatic alpha-amylases has established a role in the management of blood glucose in hyperglycemia associated with non-insulin-dependent diabetes mellitus [80].…”

The effect of barium and strontium on activity of glucoamylase QsGH97a from Qipengyuania seohaensis SW-135

“…Furthermore, QsGH97a showed greater resistance to high concentrations of salt, detergents, and organic solvents in the presence of metal ions Ba 2+ or Sr 2+ . A novel esterase and an α-Glucosidase were also characterized in Qipengyuania seohaensis SW-135, which are highly alkaliphilic, halotolerant, and resistant to detergents and organic solvents 29 , 30 . The research has confirmed that this bacterium was a mildly halophilic bacterium and did not grow in a medium without NaCl or with addition of > 9% NaCl 28 .…”

Enzymatic properties of alcohol dehydrogenase PedE_M.s. derived from Methylopila sp. M107 and its broad metal selectivity

“…Protein samples were desalted and concentrated by a series of dilution/concentration steps, using 50 kDa Amicon Ultra centrifugal filter units (Millipore), until the concentration of imidazole reached below 1 μM. The protein was separated by 12.5% SDS-PAGE gel electrophoresis, and the concentration was measured by the method of Bradford with bovine serum albumin (BSA) as a standard ( Zhai et al, 2022 ).…”

“…Kinetic parameters were determined using the respective optimal assay conditions using varying concentrations of selected substrates (0.001 to 1 mM). The values of K m and V max were obtained using the Michaelis–Menten equation, with GraphPad Software (GraphPad prism5, United States) ( Zhai et al, 2022 ). Averages of kinetic constants were determined for each enzyme based on three biologically independent experiments.…”