BIOINORGANIC CHEMISTRY A Short Course Second Edition

400 IRON-CONTAINING PROTEINS AND ENZYMES

TABLE 7.7 Selected Substrate/Inhibitor Contacts at Q

and Q o

Sites in Cytochrome bc i

1

Q

Site o

PDB No.(Substrate/Inhibitor)

Ar - Ar or

hydrophobic

contacts

his161 (H161)

(from ISP, [2Fe - 2S]

ligand) (

Å )

glu271 (E271) (from cyto b, EF loop) ( Å )

tyr273 (Y273) (from cyto b, EF loop) ( Å )

1NTZ(substrate

ubiquinone - 2 (UQ2)

phe274met124ala125met129

O

· · · H161 N 4

= 4.6 ε 2

O

· · · E271 N = 4.1 2

O

· · · H 2

O 2

1069

= 2.8,

H

O 2

1069

· · · E271 N =

3.1

1SQP(inhibitor

myxothiazol, MYX)

phe274

O

· · · E271 N = 2.84 1

N

· · · Y273 O 1 (OH) = 3.1

1SQX(inhibitor

stigmatellin, SMA)

phe274met124ala125met129

O

· · · H161 N 4

= 3.0ε 2

O

· · · H161 N 5

= 3.6 ε 2

O

(OH) · · · E271 O 8

= ε 1

2.7

1PP9(inhibitor

stigmatellin, SMA)

phe274

O

· · · H161 N 4

= 2.8 ε 2

O

(OH) · · · E271 O 8

= ε 1

2.6

1PPJ(inhibitor

stigmatellin, SMA)

phe274

O

· · · H161 N 4

= 2.7ε 2

O

· · · H161 N 5

= 3.5 ε 2

O

(OH) · · · E271 O 8

= ε 1

2.6