Table 1.

Substrate specificity of 4CL in aspen xylem crude extracts and of E. coli-expressed Pt4CL1 and Pt4CL2 recombinant proteins

Substrate	Specific activity*, pkat/mg protein
	Aspen xylem extracts	Purified recombinant Pt4CL1	Purified recombinant Pt4CL2
4-Coumaric acid	738.89  ±  19.25	11484.48  ±  128.30	1878.95  ±  41.40
Caffeic acid	250.00  ±  8.33	5944.44  ±  146.99	578.14  ±  15.65
Ferulic acid	411.67  ±  22.05	8222.22  ±  192.45	496.84  ±  15.65
5-Hydroxyferulic acid	91.67  ±  14.43	2166.67  ±  146.99	0

^*Specific activities were mean ± SD (n = 3 independent assays).