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. 2003 Jul;12(7):1455–1463. doi: 10.1110/ps.0356203

Table 3.

Salt-bridge and hydrogen-bond interactions between the protein and the PLP and FMN at the active site of three PNPOx enzymes

Distancea
Ligand Water Proteinb Human Escherichia coli Yeast
PLPc
N1 W1 Trp206A NE1 3.3:3.2 3.4:3.3
O3′ His227B NE2 2.7 2.6
O4′ W2 Glu77A OE1 3.1:2.6 3.1:3.5 (Asp)
OP1 Lys100A NZ 2.7 3.0
OP2 Tyr157A OH 2.8 2.5
OP2 Arg161A NE 2.7 2.6
OP3 Arg161A NH1 2.9 2.7
OP3 Arg225B NH2 2.7 2.9
OP3 Ser165A OG 3.5
OP3 W3 Ser165A OG 2.7:2.5
FMN
O2 Thr111A OG1 2.8 2.8 3.1 (Ser)
O2 Glu174A NE2 3.1 3.1 3.1
N3 Phe110A O 2.9 2.8 (Tyr) 3.6 (Tyr)
O4 Leu98A N 3.3 3.2
O4 W4 Phe110A N 2.7:2.7 2.7:2.8 (Tyr)
N5 Leu98A N 3.4 3.4
O2* Met96A O 2.7 2.7 (Ile) 2.3 (Ile)
O2* Gln139B NE2 3.1 2.8 3.2
O3* Trp219B NE1 3.4 3.5 3.5
O3* W5 Pro261B OXT 2.7:3.0 2.8:2.8
O3* W6 Trp219B NE1 2.8:2.5 2.8:2.8
O3* W7 Glu217B OE1 2.7:2.5 2.7:3.1
O4* Lys117A NZ 2.7 2.8
O4* Gln174A NE2 3.1 3.2
O4* Arg138A NH2 2.7
O4* Arg229A NH2 2.9
O5* Lys117A NZ 3.4 3.3 2.7
O5* Arg141B NH1 3.3
O1P Arg95A NE 2.8 2.7 2.6
O1P Arg141B NH2 2.8 — (Met) 2.9
O1P W8 Arg116A NH1 2.9:2.5
O2P Ser175A OG 3.5 3.1 2.4
O2P Arg116A N 3.2 3.3
O2P Lys117A NZ 2.9 2.8
O3P Arg229B NH2 2.8 3.0 2.9
O3P Ser175A OG 2.7 2.6
O3P Arg116A NE 3.1 2.9
O3P Lys117A N 2.6
O3P W9 Arg116A NH2 2.9:2.9

a Interactions that are less than 3.6 Å are listed.

b Nonidentical residues are shown in parentheses.

c Only the human and E. coli PNPOx have PLP bound at the active site.