C13‐Deacylase from Nocardioides albus Resp. Streptomyces sp., Catalyzing Side Chain Hydrolysis on the Taxane Core

An enzyme that has been identified and characterized as capable of hydrolyzing paclitaxel (Taxol), a key anticancer drug derived from Pacific yew (Taxus brevifolia) has been identified. Molecular docking (MD) simulations map the catalytic triad and critical residues that drive substrate-enzyme interactions. The findings indicate the catalytic potential for synthesis.

Abstract

The enzyme C13DAc, isolated and characterized from Nocardioides albus ATCC 55425, represents a novel hydrolase with a classical Ser-His-Asp catalytic triad. Notably, it displays a distinct substrate profile, exhibiting no activity toward conventional esterase substrates such as p-nitrophenyl esters or cinnamate esters. Instead, C13DAc hydrolyzes compounds with a taxane core (e.g., paclitaxel), indicating a specialized biocatalytic function. Computational models provided critical insights into the architecture of the enzyme's active site. Molecular docking simulations revealed the catalytic triad positioned within a hydrophobic pocket and identified hydrophobic residues essential for substrate binding. The mutagenesis of a tyrosine residue led to the complete abolition of activity, thereby indicating an essential role for stabilizing the oxyanion intermediate. The substrate spectrum of C13DAc has been found to correlate with ligand hydrophobicity and structural specificity, thereby supporting the predicted binding mode and suggesting potential substrate combinations for synthetic applications. While transesterification reactions are feasible, the enzymatic esterification required for paclitaxel synthesis remains a significant challenge. These results underscore the potential of C13DAc as a promising candidate for biotransformation processes, particularly in the modification of complex natural products such as paclitaxel derivatives.

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