Cofactors Flashcards
What are the two types of cofactors used by enzymes
inorganic ions (Mg2+, Fe2+, Mn2+, etc.)
coenzymes
What are coenzymes
complex organic or metalloorganic compounds that act as transient carriers of specific functional groups
Many cofactors are derivatives of ________________
adenosine
What is the carrier/donor of phosphate groups
ATP
What is the function of ATP at the cellular level (what is it doing to other molecules)
phosphorylate other molecules
What is the coenzyme that acts as a carrier of acyl (acid) groups
coenzyme A
What is coenzyme A derived from
pantothenic acid (B5)
Looking at the structure of coenzyme A (CoA/CoASH) what is the general feature of its structure
horizontal and very long
CoASH (coenzyme A) forms ________________ derivatives with organic acids
thioester (sulphur analogue of an ester)
What is the name for the thioester derivative formed by CoASH and organic acids
acyl CoA
In the specific case of acetic acid, what is the name of the thioester derivative formed by CoASH
acetyl CoA
What are NAD+, NADP+, FAD, and FMN used for
universal electron carriers
Why is it important that NAD+, NADP+, FAD and FMN act as universal electron carriers
electrons are removed from the substrates and transferred onto these cofactors, reducing them, and conserving the energy of oxidation
Which of NAD+, NADP+, FAD, and FMN are involved in beta oxidation
NAD+ and FAD
NAD+ and NADP+ are the _________________ nucleotides
pyridine
What are NAD+ and NADP derived from
niacin (B3)
Looking at the structure of the pyridine nucleotides, what is the general feature of its structure
Have a pyridine ring, and are two structures stacked on top of one another connected by a phosphate backbone looking structure
During oxidation of NAD+ and NADP+, ____ _____________ atoms are removed from the substrate
2 hydrogen atoms
The oxidized form of NAD+ and NADP+ accept a ___________ ion to become reduced
hydride
the other hydrogen is just released into the aqueous environment
NAD+ is used as the ______________ agent in catabolic processes
oxidizing agent
NADPH is used as the ______________ agent in biosynthesis
reducing agent
If NAD+ is used as the oxidizing agent (being reduced), where is it reoxidized
in the electron transport chain
FAD and FMN are the _______________ nucleotides
flavin
FAD and FMN are derived from __________________
riboflavin (B2)
Flavin nucleotides usually act as ______________ groups; found tightly bound to the enzyme
prosthetic
Looking at the structure of FAD and FMN what is the general feature of its structure
vertical and very long
Flavin nucleotides can accept either ____ or ____ electrons in the form of ____ or ____ ______________ atoms
accept either 1 or 2 electrons in the form of 1 or 2 hydrogen atoms
What are the FULLY reduced forms of FAD and FMN
FADH2 and FMNH2
What are the forms of FAD and FMN when only one electron is accepted (and one unpaired electron still exists) AND what is the name of these forms
FADH and FMNH
semiquinone radical forms
Why is there a greater diversity of reactions in FAD and FMN than in NAD and NADP
since FAD and FMN can accept either one or two electrons, there is a greater diversity of reactions possible when compared to the NAD(P)-linked dehydrogenases
Cofactor CoA is the carrier of…
acids
Pyridine cofactors are carriers of…
electron pairs
Flavin cofactors are carriers of…
electrons (doesn’t have to be pairs)
CoA is derived from which B vitamin
B5 - pantothenic acid
Pyridine are derived from which B vitamin
B3 - niacin
Flavins are derived from which B vitamin
B2 - riboflavin
