. 2004 Dec;13(12):3200–3213. doi: 10.1110/ps.04828404

Table 2.

Frequencies of conservation of selected amino acid residues in family GH16 XTHs and (1,3;1,4)-β-d-glucanases

XTHs
Residue^a	Tyr75^d	His83	Tyr99^d	Phe106	Tyr170^d	Trp174^d	Trp179
Frequency^b	96	75 (90)	77 (92)	49 (100)	76 (84)	96	90
(1,3;1,4)-β-d-glucanases
Residue^c	Phe92	Trp103	—	Tyr123	Met180	Trp184	Trp192
Frequency^b	96	75 (90)		49 (100)	79	96	80 (81)

Amino acid residues having the same position are aligned with each other in the table.

^a Amino acid residues in XTHs corresponding to residues of the V. angularis and P. tremula × tremuloides enzymes.

^b Frequencies are expressed in percentages. The numbers in parentheses are the frequencies of all aromatic amino acid residues observed in that position.

^c Amino acid residues in (1,3;1,4)-β-d-glucanases corresponding to residues of the B. macerans enzyme.

^d These residues have the same 3D position in the XTHs and in the β-d-xylan endohydrolases, and are designated the “aromatic triad.”