BIOINORGANIC CHEMISTRY A Short Course Second Edition

C88

A172

A+1

P Mg 2

Mg 1

O1P, C88

G170

O1P, G170

O1P, A172

O2P, A172

exon-exon

bond

formationnucleophile

O3’, U-1

leaving group

O3’, ωG, G206

P, Phosphorus of

scissile

phosphate, A1

Distance = 3.2 A,

Bond angle for O3’,

U-1 (nucleophile) - P,

A+1 - O3’, ωG (G206,

leaving group) = 175o

5MU, U-1

ωG, G206

G128

O2’, ωG

O1P,

G128

pro-Rp O,A+1

1ZZN catalytic site

Figure 6.8 A group I intron transition state stabilized by two magnesium ions (PDB:
1ZZN). Visualized using CambridgeSoft Chem3D Ultra 10.0 with notations in Chem-
Draw Ultra 10.0. (Printed with permission of CambridgeSoft Corporation.)

Figure 6.22 X - ray crystallographic structures of: (A) Ca 2+ - saturated calmodulin, PDB:
1EXR; and (B) apo - calmodulin, PDB: 1QX5. Visualized using CambridgeSoft Chem3D
Ultra 10.0 with notations in ChemDraw Ultra 10.0. (Printed with permission of Cam-
bridgeSoft Corporation.)

helix A (I)

helix B (II)

helix C (III)

helix D (IV)

helix E (V)

helix F (VI)

helix G (VII)

helix H (VIII)

1EXR

A

helix H (VIII)

helix G (VII)

helix C (III)

helix D (IV)

helix E (V) helix F (VI)

helix A (I)

helix B (II)

B

1QX5