Proteins and Enzymes

Alcohol denaturants
compete for H bonds which are involved in maintaining higher levels of protein structure
Acid and Base denaturants
ACID- protonate carboxylate functions which removes their charge; destroy salt bridges
BASE- deprotonate ammonium which removes charge; destroys salt bridges
Urea denaturants
competes for H bonds which are responsible for maintaining higher levels of protein structure
Heat denaturants
increases thermal motions which disrupt noncovalent interactions
heavy metals
bond to free thiol function (-S-H) and cause protein to precipitate
coenzymes
most are made from b-vitamins
loosely or tightly bound to enzyme
tightly bound coenzymes are considered to be prosthetic groups
NAD+
coenzyme required by most but not all dehydrogenases
remove hydrogen from substrate
binds a hydride ion to become NADH
monomeric
a single polypeptide chain
prosthetic group
nonprotein molecule that a protein require for activity
prosthetic group of myglobin
heme, an iron 2+ ion ( Fe 2+ coordinated to a poryphorin ring)
why doesn’t myoglobin have quaternary structure?
it is a monomeric protein so it doesnt have interactions between chains
hemoglbin/myoglobin similar/different
both are oxygen carriers
both use heme as a prosthetic group
myoglobin is monomeric
hemoglobin is tetrameric
why does hemoglobin have quaternary structure while myglobin does not
because hemoglobin is tetrameric so multiple chains can interact while myoglbin is monomeric so it doesnt have multiple chains
eneatiomer
an optical isomer that is non-suoerimposable on its mirror in=mage
racemic mixture
an optically inactive mixture that consists of equal amounts of a pair of enantiomers
disstereomers
structures that belong to the same family of optical isomers but are related as enantiomers
dextrorotatory
an optical isomer that rotates the plane of light to the right
levorotatory
an optical isomer that rotates the plane of light to the left
optically active
a substance able to rotate the plane of light
how do A.A. residues which are typically far apart in promary structure get close to each other to form the active site?
the protein must fold properly
dehydrogenases
class of enzymes that catalyzes the removing of hydrogen from substrates in catabolic pathways like glycolysis and Krebs Cycle
NAD+
most dehydrogenases must use this and are NAD+ dependent
FAD
some dehydrogenases use this as the electron/proton carrier and are therefore FAD dependent
carbs digest —-> glucose, sugars/glycolysis —-> pyruvate —-> acetyl CoA/citric acid cycle—–>reduced coenzymes/ETC —> ATP
places where products of A.A. can join central metabolism pathway
acetyl CoA, pyruvate, citric acid cycle intermediates
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