another example:

Carbonic Anhydrase

Zn

Zn

Active site in -carbonic anhydrase

Active site and mechanism in -carbonic anhydrase

deprotonation

Nucleophilicattack on CO2

Charge stabilization

START

:B(GLU)H+:B(GLU)

CO2 --> [CO3]2-

CO2 --> glucoseCO2 <-- [CO3]2-

glucose --> CO2

Carbonic Anhydraseis critically important in global C- cycle

CO2 --> [CO3]2-

CO2 <-- [CO3]2-

Carbonic Anhydraseimportant in global C- cycle because catalyzes both directions!

Phytoplankton do this:HCO3

- CO2

Diatoms do this:CO2 HCO3

-

CA importance means these critters are growth limited:when there’s too little Zn, can use Cd and Co!!

Acid/base chemisty in catalysis of Mo enzymes: oxidation of SO32-

See in this step how

Mo charge affects H2O

acidity

ditto