Two- way dynamics in β-glucosidase catalysis

• Published in: Journal of molecular catalysis. B, Enzymatic Vol. 133; pp. 161 - 166
• Main Authors: Sawant, Sneha, Birhade, Sachinkumar, Anil, Annamma, Gilbert, Harry, Lali, Arvind
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-11-2016
• Subjects: Glucose inhibition; Hydrolysis; Transglycosylation; β-Glucosidase; EDP1; DP1; E; DP3; DP2; DP5; DP4; DP6; DP; Glucose inhibition; Hydrolysis; Transglycosylation; Vglu; β-Glucosidase; Vcel; Vtri
• ISSN: 1381-1177; 1873-3158
• DOI: 10.1016/j.molcatb.2016.08.010

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•β-glucosidase exhibits dual activity of hydrolysis of cellobiose to glucose and synthesis of cello-oligosaccharides from glucose and cellobiose simultaneously.•Ratios of Cellobiose to Cellotriose concentrations in reaction determines the switch for dual activity.•Simultaneous hydrolysis and transglycosylation is responsible for slow rate of cellulose hydrolysis.
Product inhibition of β-glucosidase is considered as one of the central rate limiting steps as it starts accumulation of intermediates responsible for the slowdown of the cellulose hydrolysis. Feedback inhibitions exhibited by glucose and other oligosaccharides on the cellulose hydrolyzing enzyme reduces the rate of hydrolysis bringing the entire process to standstill. However, the exact mechanism of this catalytic slowdown is still elusive. In present study, β-glucosidases were investigated for their activities under high glucose and cellobiose concentrations. β-glucosidases recognizes cellobiose a true substrate and hydrolyzes it resulting in glucose or transglycosylates it to give cellotriose. Our observation highlight that rates of reaction for cellotriose synthesis and glucose formation are mainly concentration driven and are dynamically adjusted based on cellobiose concentration in the reaction system. We therefore conclude that critical concentration of DP2: DP3 influences hydrolysis or transglycosylation and any modulation to this ratio influences the dynamics of β-glucosidases hydrolysis.