The present invention relates to an improved process for the preparation of 2, 4-dihydroxybutyrate from a
carbon source via
homoserine, comprising a two-step
route: a first step of catalytically converting the primary amino group of
homoserine to a
carbonyl group by an
enzyme having
homoserine transaminase activity as defined by E.C.2. 6. 1.1 or E.C.2. 6. 1.42 or E.C.2. 6. 1.57 to obtain 2-oxo-4-hydroxybutyrate, and a second step of catalytically converting the primary amino group of homoserine to a
carbonyl group by an
enzyme having homoserine
transaminase activity as defined by E.C.2. 6. 1.1 or E.C.2. 6. 1.57 to obtain 2-oxo-4-hydroxybutyrate. And-a second step of catalytically reducing the obtained 2-oxo-4-hydroxybutyrate (OHB) to 2, 4-dihydroxybutyrate by an
enzyme having OHB
reductase activity, the enzyme having OHB
reductase activity being a
lactic dehydrogenase as defined by E.C. 1.1. 1.27 or E.C. 1.1. 1.28, or a
malate dehydrogenase as defined by E.C. 1.1. 1.37, E.C. 1.1. 1.82, or E.C. 1.1. 1.299, and-a second step of catalytically reducing the obtained 2-oxo-4-hydroxybutyrate (OHB) to 2, 4-dihydroxybutyrate by an enzyme having OHB
reductase activity, the enzyme having OHB
reductase activity being a
lactic dehydrogenase as defined by E.C. 1.1. 1.28, or a
malate dehydrogenase as defined by and wherein at least one enzyme having aldolase activity, as defined by E.C.4.1. 2.28, is inactivated to prevent degradation of OHB.