Lec23 - Covalent catalysis Transient substrate enzyme...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Covalent catalysis Nucleophilic attack by the enzyme E-S intermediate promotes reactivity elsewhere in the substrate Elimination of the enzyme Transient substrate enzyme intermediate
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Decarboxylation of acetoacetate
Background image of page 2
What does the enzyme provide Fix the substrate Nucleophile A basic and an acidic group
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
More stable the covalent intermediate is, less easily it can dissociate into products; Aasy reversal of the bond formation is an important property of covalent catalysis; Groups with high mobile electrons are better for covalent catalysis
Background image of page 4
Metal ion catalysis Metallo-enzymes Fe 2+ , Fe 3+ , Zn 2+ , Mn 2+ Mg 2+ ,Ca 2+ Catalysis Metal-activated enzymes Na + , K + , Mg 2+ Ca 2+ Structural
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Metal ions participate in catalysis in several ways Substrate binding Oxidation-reduction reactions Stabilize negative charges
Background image of page 6
Zn 2+ — coordinated by 3 His and 1 H 2 O H 2 O is polarized (pulling on the unbound electrons) This allows a fourth His to pull a proton from the H 2 O molecule
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 28

Lec23 - Covalent catalysis Transient substrate enzyme...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online