Enzyme CoFactors Flashcards
1
Q
types of cofactors
A
- inorganic ions: Fe2+, Mg2+, Mn2+, Zn2+, Cu2+
- coenzymes: complex organic or metaloorganic compounds that act as carriers of certain functional groups
2
Q
What are many enzymes derivatives of?
A
adenosine
- adenosine is readily available
3
Q
ATP as a coenzyme
A
- carrier/donor of phosphate group
- used to phosphorylate many molecules
- when dephosphorylated becomes ADP
4
Q
kinase
A
enzymes that phosphorylate molecules with the help of ATP
5
Q
Coenzyme A (CoA/CoASH)
A
- acts as a carrier of acyl (acid) groups
- derived from the vitamin pantothenic acid (B5)
- discovered by Fritz Lipmann
- reactive component is -SH
6
Q
what do CoA and organic acids (R-COOH) form?
A
thioester derivatives
- thioester is a sulfur analogue of an ester
- any coenzyme A thioester is called an acyl CoA
- in the specific case of acetic acid, the coenzyme A derivative is called acetyl coA
7
Q
similarities between NAD+ and FAD
A
- both universal e- carriers
- electrons that are removed from substrates are transferred onto these cofactors, conserving the energy of oxidation
- involved in beta oxidation
8
Q
NAD+ and NADP+: the pyridine nucleotides
A
- derived from vitamin niacin (B3)
- redox occurs at the nicotinamide ring
- during oxidation of substrates 2 H+ are removed from the substrate
- the oxidized form accepts a hydride ion to become reduced to NADH ir NADPH
9
Q
NAD+ vs NADPH
A
- NAD+ is used as the oxidizing agent in catabolic processes, the resulting NADH is reoxidizes via ETC to generate energy
- NADPH is used as a reducing reagent in biosynthesis
10
Q
FAD and FMN: the flavin nucleotides
A
- derived from vitamin riboflavin (B2)
- act as prosthetic groups, found tightly bound to enzymes
- can accept either 1 or 2 electrons from substrates
- fully reduced forms FADH2 and FMNH2, when only one e- is accepted they form stable semiquinoane radical forms
- involved in a greasy diversity of reactions that NAD(P)-linked dehydrigenases
