Mutant CYP2B6 Protein Affinity for Cyclophosphamide
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Solution Overview
Problem
The low affinity of wild-type CYP2B6 for cyclophosphamide limits its therapeutic effectiveness in enzyme prodrug therapy, leading to non-specific administration and severe side effects due to cytotoxic activity on non-tumor cells, necessitating improvements in catalytic efficiency and tumor specificity.
Innovation Solution
A novel mutant CYP2B6 protein with increased affinity for cyclophosphamide, achieved by mutating isoleucine to valine at position 114, leucine to methionine at position 199, and valine to tryptophan at position 477, and its fusion with NADPH cytochrome P450 reductase, enhancing enzyme activity and reducing drug requirements for effective tumor treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wild-type CYP2B6 is used in enzyme prodrug therapy, then the therapy can be administered, but the affinity for cyclophosphamide is low leading to severe side effects
Solution Approach 1:
The patent applies parameter changes by mutating specific amino acid residues in CYP2B6 (I114V, L199M, V477W) to alter the enzyme's kinetic parameters. The mutant enzyme exhibits an 8-fold increase in affinity (decreased Km from 4.91 to 0.61 µM) for cyclophosphamide while maintaining Vmax, thereby improving catalytic efficiency (Vmax/Km) by 8-fold and reducing the drug concentration required for effective tumor treatment, which minimizes systemic side effects.
2Productivity
If the affinity of CYP2B6 for cyclophosphamide is increased through mutation, then catalytic efficiency is improved, but the enzyme structure is modified
Solution Approach 1:
The patent applies local quality by introducing point mutations at specific positions (114, 199, 477) within the CYP2B6 enzyme structure. These localized amino acid substitutions (I114V, L199M, V477W) modify the active site or substrate-binding region to enhance cyclophosphamide affinity without disrupting the overall enzyme structure or folding, thereby maintaining stability while improving catalytic efficiency.
3Reliability
If CYP2B6 is used for tumor treatment, then antitumour effect is achieved, but non-specific administration causes cytotoxicity to healthy cells
Solution Approach 1:
The patent resolves this contradiction by changing the kinetic parameters of CYP2B6 through amino acid mutations. The mutant enzyme's 8-fold increased affinity (lowered Km) for cyclophosphamide enables effective prodrug activation at lower enzyme concentrations localized in tumor cells, thereby achieving adequate antitumour efficacy while reducing the risk of systemic cytotoxicity to healthy cells.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The mutant CYP2B6 protein demonstrates an 8-fold increase in cyclophosphamide affinity and 10-fold improvement in metabolic efficiency, sensitizing drug-resistant tumor cells to treatment, resulting in dramatic reductions in tumor size and reduced side effects by enhancing the therapeutic effect of cyclophosphamide.
Implementation Method 1
CYPs catalyse oxidation reactions via electron transfer from NADPH by a reductase, usually NADPH-cytochrome P450 reductase
Implementation Method 2
CYPs catalyse oxidation reactions via electron transfer from NADPH by a reductase, usually NADPH-cytochrome P450 reductase
Data Source
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AI summary
The present invention to relates mutant human cytochrome P450 2B6 (CYP2B6) proteins, and fusion proteins comprising said mutant CYP2B6 proteins. In particular, fusion proteins comprising mutant CYP2B6 and NAPDH-cytochrome P450 reductase are provided. The invention also relates to methods of treatment of cancer and the use of said proteins and fusion proteins in the treatment of cancer, in particular via virus-directed enzyme prodrug therapy.