Table S2.

Screening for substrate specificity of ChuaHNL toward aromatic aldehydes

			HPLC methods
Substrate	Configuration	ee, %	Solvent n-hexane:2-propanol	Retention time for aldehyde,min	Retention time for (R)-cyanohydrin,min	Retention time for (S)-cyanohydrin,min
Benzaldehyde	R	77.7	85:15	5.4	11.4	14.3
2-Chlorobenzaldehyde	R	11.0	97.5:2.5	6	36.4	38.7
4-Bromobenzaldehyde	R	90.0	95:5	7.9	30.5	31.8
2-Methylbenzaldehyde	R	44.9	85:15	5	8.4	9.8
3-Methylbenzaldehyde	R	89.6	85:15	5	9.7	11.2
4-Methylbenzaldehyde	R	86.9	85:15	5.3	11	14.9
2-Methoxybenzaldehyde	S	49.6	90:10–98:2 (gradient)	7.3	17.1	17.6
3-Methoxybenzaldehyde	R	72.8	85:15	6.6	14	16.8
4-Methoxybenzaldehyde	R	73.2	85:15	8.3	22.7	26.3
3-(Trifluoromethyl)benzaldehyde	R	36	85:15	4.9	6.11	6.5
4-(Trifluoromethyl)benzaldehyde	R	45	95:5	6.2	17	18.8
3-Nitrobenzaldehyde	R	39.6	85:15	16.2	19.6	22.2
4-Nitrobenzaldehyde	R	12.9	85:15	15.7	22	26.6
2,3-Dichlorobenzaldehyde	R	7.5	95:5	5.4	7.6	7.9
2,4-Dichlorobenzaldehyde	S	19.0	99:1	8.4	60.4	70.7
2,5-Dichlorobenzaldehyde	S	18.9	99:1	6	32.9	35.4
2,6-Dichlorobenzaldehyde	R	14.9	95:5	8	26.6	28.4
3,4-Dichlorobenzaldehyde	R	64.6	97.5:2.5	8.3	42.9	45.1
2,4-Dimethylbenzaldehyde	R	58.8	85:15	5	8.1	10.2
3,5-Dimethoxybenzaldehyde	R	18.7	85:15	10.5	51	55.8
Piperonal	R	70.6	85:15	10.8	22.1	24.3
Terephthalaldehyde	R	8.6	85:15	13.6	20.6	25.1
4-Biphenylcarboxaldehyde	R	83.3	85:15	12.2	27.8	30.1
2-Furancarboxaldehyde	S	40.1	85:15	7.6	13.3	10.4
2-Thiophenecarboxaldehyde	S	89.2	85:15	7.7	17.1	12.4
3-Pyridinecarboxaldehyde	R	23.7	85:15	9.2	10.3	11.5
2-Quinolinecarboxaldehyde	R	15.3	85:15	21.2	47	50.1
1-Naphthalenecarboxaldehyde	R	48.4	85:15	7.3	15.6	18.4
2-Naphthalenecarboxaldehyde	R	29.9	85:15	9.5	19	23.7

Six units of enzyme was used in citrate buffer, pH 4.2, at room temperature (22 °C), without using organic solvent in the screening step. The (S) configuration was assigned according to Cahn–Ingold–Prelog rules (46).