https://doi.org/10.15255/KUI.2025.030
Published: Kem. Ind. 75 (5-6) (2026) 301–308
Paper reference number: KUI-30/2025
Paper type: Review
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Insights into Application Limitations of Halohydrin Dehalogenases through Kinetic Studies

N. Milčić, M. Sudar, M. Majerić Elenkov and Z. Findrik Blažević

Abstract

Biocatalysis is gaining increasing importance as a scientific discipline in the field of asymmetric synthesis of pharmaceutical compounds and specialised chemicals, and has shown significant progress in industrial applications in recent years. For biocatalytic processes to be successfully developed, optimised, and integrated into industrial synthesis, they must be examined from multiple perspectives, e.g., from protein engineering for the design of new enzymes, through organic chemistry in planning synthetic pathways, to reaction engineering for process design and optimisation. This paper focuses specifically on halohydrin dehalogenases (HHDHs), a group of enzymes with great potential that, despite their promise, remain insufficiently explored. HHDHs catalyse the ring-opening reactions of epoxides in the presence of various nucleophiles, leading to the formation of new C−C, C−O, C−S, and C−N bonds, and the synthesis of β-substituted alcohols. This property makes HHDHs valuable enzymes for the production of important compounds such as drugs, agrochemicals, and fine chemicals. Despite the justified significant interest shown by the scientific and industrial community toward this group of enzymes, which has consequently led to the implementation of HHDH-catalysed reactions in pharmaceutical production, the kinetic characteristics of this group remain largely unknown. Challenges such as various enzyme inhibitions and decreased operational stability under synthetically relevant conditions are still poorly explored. Since addressing these issues through detailed kinetic studies is crucial for expanding the practical applications of HHDH in synthetic processes, this review paper is conceived as a discussion of recent and relevant research on the kinetic characteristics and limitations of this group of enzymes, collected over several years of practical experience and laboratory work with HheC from Agrobacterium radiobacter and its variants, primarily in the synthesis of fluorinated β-azido alcohols and β-hydroxy nitriles.

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Keywords

halohydrin dehalogenases, HHDH, enzyme kinetics, enzyme inhibitions, operational stability of enzymes