TABLE 3.

Synergistic effects between noncellulosomal subunits and cellulosomal subunit XynA in plant cell wall degradation

Substrate	Degradation activity (μg/ml)a						Synergism coefficientd
	rArfA	rBgaA	rXynAb	rArfA and rXynA	rBgaA and rXynA	rArfA, rBgaA, and rXynA	A + X	B + X	A + B + X
Arabinoxylan	77.2	1.4	267.7	607.2	208.7	595.3	1.8	0.8	1.7
Arabinogalactan	1.5	8.9	7.0	7.4	25.7	20.2	0.9	1.6	1.2
Corn fiber gum	47.5	3.0	75.7	247.9	95.0	285.0	2.0	1.2	2.3
Corn stem powderc	8.9	1.5	20.1	78.7	26.7	89.1	2.7	1.2	2.9

^aThe degradation activity is expressed as the amount of reducing sugar released per milliliter of reaction mixture. The reaction mixture was composed of 0.5% substrate (wt/vol), 50 mM phosphate buffer (pH 6.0), and a 0.2 μM concentration of each enzyme. The reaction was performed under gentle shaking conditions at 37°C for 15 h.

^brXynA from C. cellulovorans endo-1,4-β-xylanase A was cloned previously (GenBank accession no. AF435978).

^cCorn stem powder was prepared as described previously (20).

^dThe synergism coefficient indicates the ratio of measured to theoretical activity. Symbols: A + X, rArfA plus rXynA; B + X, rBgaA plus rXynA; A + B + X, rArfA, rBgaA, and rXynA. Results are means of three determinations.