Table 2. Activity of ArCE4A against different substrates.

Substrate	Substrate concentration	ASARa (μM)	Average acetic acid release (μM)	CV%	Deacetylation degree (%)	Acetic acid released (nmol/min)	Apparent rate constant (s-1)
GlcNAc	2 mM	2000	0.0	0.0	0.000	0.00	0.00
(GlcNAc)2	2 mM	4000	0.1	14.5	0.003	0.00	0.00
(GlcNAc)3	2 mM	6000	11.9	2.6	0.20	0.04	0.02
(GlcNAc)4	2 mM	8000	39.8	2.8	0.50	0.13	0.07
(GlcNAc)5	2 mM	10000	95.8	7.7	0.96	0.32	0.18
(GlcNAc)6	2 mM	12000	39.4	0.2	0.33	0.13	0.07
Chitosanb	5 mg/ml	16000	85.4	1.4	0.53	0.28	0.16
α-chitin	5 mg/ml	24600d	0.8	6.4	0.003	0.00	0.00
β-chitin	5 mg/ml	24600d	1.4	1.9	0.006	0.001	0.00
Acetyl xylanc	5 mg/ml	9000	1696.7	3.1	18.9	5.66	3.14

The substrate was incubated with 300 nM ArCE4A for 30 min at 37°C, and released acetic acid was measured by ion exchange HPLC.

^aASAR: amount of substrate expressed as the concentration of acetyl groups.

^bThe degree of acetylation was 64%.

^cMW_avg = 2800, degree of acetylation roughly estimated to be around 50% by MALDI-TOF.

^dAssuming one acetylation per sugar unit.