Corrigendum: Scalable and Selective β‐Hydroxy‐α‐Amino Acid Synthesis Catalyzed by Promiscuous l ‐Threonine Transaldolase ObiH

Compound 22 was incorrectly drawn as the isomer being derived from 1-napthaldehyde, when it was instead derived from 2-napthaldehyde. Compound 15 should also be drawn as a carboxylate, and not a carboxylic acid. A corrected Figure 2 is provided. Analytical and preparative-scale synthesis of β-hydroxy-α-amino acids by ObiH. Reactions were performed using 20 mM aldehyde, 100 mM l-Thr, 50 mM Tris pH 8.5 and 1–2% ObiH wet whole cells, with 4 % (v/v) MeOH as co-solvent. Preparative scale reactions were incubated at 37 °C for 18 h before quenching with 1 volume equivalent of MeCN, followed by freeze-thaw and centrifugation to remove cell debris. Purification was achieved using a Biotage purification system via reverse-phase chromatography. Yields are reported as isolated product mass after lyophilization. 1H NMR hydration analysis was used to correct yield values for excess water. Analytical scale product yields determined by UPLC-PDA-MS following derivatization with Marfey's reagent. A correction to the corresponding text has also been made on Page 4, paragraph 2: “Instead, to further probe the limits of the ObiH active site, we sought to challenge the enzyme with sterically bulky aromatic aldehydes to generate napth-1-ylserine (22) and biphenylserine (23) (Figure 2).” Should state: “Instead, to further probe the limits of the ObiH active site, we sought to challenge the enzyme with sterically bulky aromatic aldehydes to generate napth-2-ylserine (22) and biphenylserine (23) (Figure 2).” A correction to the Supporting Information is also noted. On page 11, the synthetic procedure to generate compound 22 should read as follows: (2S,3R)-2-amino-3-hydroxy-3-(naphthalen-2-yl)propanoic acid (22) Thr dissolved in 100 mM Tris pH 8.5 (953 mg, 8.01 mmol, 100 mM final conc.), 2-napthaldehyde (250 mg, 1.6 mmol, 20 mM final conc.), 3.72 mL MeOH (4 % v/v), and 24.0 mL 100 mM Tris-HCl, pH 8.5 buffer (final buffer concentration: 50 mM) and were added to a 0.5 L glass bottle with a sealable lid. MQ water was added to a final volume of 93 mL. Whole E. coli cells containing overexpressed wild-type ObiH were added to a final concentration of 20 mg/mL (2 % w/v). The reaction mixture was incubated at 37 °C for 18 h while shaking at 250 rpm to ensure thorough mixing. The reaction mixture was then quenched by the addition of 1 volume equivalent of acetonitrile, followed by freeze-thaw to improve material recovery from cells. The thawed mixture was transferred to 50 mL conical vials and centrifuged at 4,300×g for 10 minutes to pellet insoluble whole cells. The supernatant was transferred to a 1.0 L round bottom flask and concentrated by rotary evaporation. For purification, the resulting reaction mixture was loaded onto a Biotage SNAP Ultra 30g C18 column and purified on a Biotage flash purification system using a water/methanol gradient. Fractions were analyzed by UPLC-MS to identify product containing fractions. All product containing fractions from both rounds of purification were then pooled, concentrated by rotary evaporation, and dried via lyophilization, yielding a white solid (69 mg isolated). Hydration analysis: C13H13NO3 ⋅ H2O, 17 % yield. 1H NMR (400 MHz, MeOD) δ 7.96 (s, 1H), 7.93–7.80 (m, 3H), 7.57 (dd, JH-H=8.5 Hz, 1.8 Hz, 1H), 7.52–7.42 (m, 2H), 5.35 (d, JH-H=3.7 Hz, 1H), 3.74–3.65 (m, 1H); 13C{1H} NMR (125 MHz, MeOD) δ 176.19, 140.04, 134.59, 134.35, 129.22, 129.04, 128.60, 127.22, 126.99, 126.01, 125.26, 78.28, 62.39; HR-ESI-MS: m/z calcd for C13H13NO3 [M−H]−: 230.0823, found: 230.0823. The conclusions of the paper are not otherwise affected. The authors apologize for this error.