system
Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, RESULTS. Meshes: Amino Acid Substitution, Carboxymethylcellulose Sodium, Cellulose 1,4-beta-Cellobiosidase, Cloning, Molecular, Enzyme Stability, Gene Expression, Glycosylation, Hydrogen-Ion Concentration, Kinetics, Mutagenesis, Site-Directed, Mutant Proteins, Pichia, Temperature, Trichoderma.
user
Are substrate affinity and catalytic efficiency improved by decreasing glycosylation sites in Trichoderma reesei cellobiohydrolase I expressed in Pichia pastoris? Context: To modify two main N-glycosylation residues of cellobiohydrolase I from Trichoderma reesei by site-directed mutagenesis for decreasing the extent of glycosylation and exploring possible effects on its properties. Asparagine 45 and 64 residues were mutated to alanine to make single/double mutants and expressed in P. pastoris. Decreasing N-glycosylation of the recombinant CBH I resulted in an increased affinity of the enzyme for carboxymethylcellulose and also improved the Kcat/Km while the specific activity was decreased. Also, the enzymes were stable up to 80 °C. There was no significant change of the optimum pH and temperature by decrease of glycosylation in the mutated enzymes in comparison to the wild-type at constant incubation time of assay.
assistant
Post-translational glycan-modification of CBH I in P. pastoris has different impacts on the properties of the secreted enzymes. Substrate affinity and catalytic efficiency were improved significantly while the activity and high temperature stability were negatively affected. Final Decision: yes