Lesson 8 - metabolism and vitamins Flashcards
what are recurring energy carrying molecule motifs
primarily ATP
what are recurring electron carrier motifs
NAD(P), NAD(P)H + H, FAD, FMN, FADH2, FMNH2
what is a recurring “2 C” carrier motif
acetyl CoA
what are two subdivisions of cofactors
essential ions and coenzymes
what are two subdivisions of essential ions
activator ions (loosely bound) and metal ions of metalloenzymes (tightly bound)
what are two subdivisions of coenzymes
cosubstrates (loosely bound) and prosthetic groups (tightly bound)
what is the reaction for NAD to NADH
NAD + 2 H+ + 2 e+ —-> NADH + H+
where is the reactive site for NAD+
on the carbon directly across from the N+ in the ring structure
where is the reactive site for NADP+
the same place as NAD+
what is the reactions for NAD+ to NADH
two R groups lead to a CHOH. you add NAD+ and it takes the two hydrogens leaving a carboxyl group and NADH + H+
where are the reactive sites on FAD
the top middle N and the bottom right N
what is the reaction for FAD to FADH2
FAD takes two hydrogen and two electrons and attaches them to its two reactive sites to make its reduced form FADH2
describe how oxygen esters are stabilized
they’re stabilized by resonance structures not available to thioesters
what is vitamin precursor for NADH and NADPH
nicotinate (niacin)
what is vitamin precursor for FADH2
riboflavin (vitamin B2)
what is vitamin precursor for FMNH2
riboflavin (vitamin B2)
what is vitamin precursor for coenzyme A
pantothenate
what is vitamin precursor for thiamine pyrophosphate
thiamine (vitamin B1)
what type of reaction is thiamine (B1) involved in
aldehyde transfer
what type of reaction is riboflavin (B2) involved in
redox reaction
what type of reaction is nicotinic acid (niacin) involved in
redox reaction
what type of reaction is pantothenic acid involved in
acyl-group transfer
compare B vitamins to other vitamins
B vitamins function as coenzymes. vitamins A, C, D, E, and K play a variety of roles, but do not serve as coenzymes
name 3 regulators of enzyme activity
allostery (inhibitors or activators), covalent modification (phosphorylation), and control of gene expression (steroid hormone in mammals; operons in bacteria)
name the first general property of allosteric enzymes
activity of allosteric enzymes are changed by inhibitors and activators (modulators) which bind to an enzyme and alter its geometry in the active site
name second general property of allosteric enzymes
they possess quaternary structure
name third general property of allosteric enzymes
there is a rapid transition between the active (R) and inactive (T) conformations
name fourth general property of allosteric enzymes
the R form will be more active (lowering the apparent Km) while the T form will be less active (higher apparent Km)
describe control of gene expression in allosteric enzymes
binding of specific molecules to promotor regions in DNA increases/decreases gene expression. For example, steroid hormones in mammals bind to a receptor which translocates to the nucleus. In bacteria operons are controlled by specific molecules (for example, amino acids, lactose, etc.)
what is the difference between FMN/FAD and NAD(P)+
the oxidized or reduced forms of FMN and FAD are always prosthetic groups while the oxidized and reduced forms of NAD(P)+ are always soluble cosubstrates
