glycolysis Flashcards
what glucose units are absorbed by intestine and transported to bloodstream
D-glucose
what do amylases do
- randomly break down internal alpha 1-4 bonds
what will amylase not digest
cellulose
where is amylase located
in saliva and small intestine
what type of digestion doesn’t occur in the stomach
starch because it is stopped by HCL
what sugar is in the small intestine
alpha glucosidase (maltase)
what is D glucose
absorbed by intestine and transported to the bloodstreem
what bonds have energy
c-h, c-c and c-oH
you can capture energy from oxidizing what
carbon
what is an example of oxidizing energy from carbon
- make reduced redox factors NADH
- high energy compounds like PEP and 1,3 BPG
what is the most reduced state of carbon
CH2
what is the most oxidized state of carbon
CO2
where does glycolysis occur in prok
in the cytosol
in euk where does glycolysis occur
in the cytosol
where does Krebs, ETC/Ox phos occur
in the mitochondria
what do they do to the C’s in glycolysis
oxidize them to release energy
what do they capture some of the enrgy as
NADH and use it to make high energy phosphate 1,3-BPG and PEP
what do they make ATP from
substrate level phosphorylation
what atom do the steps involving atp + enolase
need Mg+2 because it is a metal ion cat
what are the main control points for glycolysis
step 1
step 3
step 10
how many Kcal do carbohydrates have
4 Kcal
what is the name of the glucose transporter and what transport does it do
GLUT4
in glut4 what does hexokinase do
traps Gle as G6P in cytosol
what does Metal ion catalysis by charge shielding do to the gamma phosphorous
makes it more accessible for nucleophillic attack C-6 oH
when fructose turns into glucose what intermediate is used
the enediol
describe phosphoglucose isomerase
- rxn is reversible
-general acid base catalysis - enediol intermediae
describe phosphofructokinase PFK
- reversible step
- adds phosphate groups to other molecules
-MAIN CONTROL POINT
what does aldolase do
enzyme tht turns 1,6FBP to GAP and DHAP
describe aldolase
-lyase that removes dhap and gives double bond
- reversible because lyases are reversible
what clevage does aldolase go through
aldol cleavage
- retro/reverse aldol condensation
Triose Phosphate isomerase
- reversible
-general acid base catalysis
-enediol intermediate
does equilibriym favor DHAP or GAP
it favors DHAP
what type of motif does triose phosphate isomerase (TIM) have
alpha/beta barrel fold
glycolysis stage II starts with what
GAP3DH) its a dehydrogenase
why is glyceraldehye-3-phosphate Dehydrogenase important
it generates the first high energy intermeduate
what does GAP3DH use to generate the intermediatre
inorganic Pi
what are dehydrogenases
reeox enzymes (oxireductases)
what is a oxireductase
- electrons are transferred between molecules
- example dehydrogenase
what is a transferase
- transfer functional groups like methyl and phosphate
example: kinases
what is a hydrolase
catalyze the cleavage of bonds through the addition of water
ex: proteases, nucleases, lipases
what is a lyase
catalyze the addition or removal of groups to form double bonds or break
ex: decarboxylases, aldolases
what is a ligase
catalyze the joining of two molecules
ex: dna ligase, synthetases
what does isoermase
rearrangement of atoms within molecule
ex. epimerases, racemases
how much NADH +h does GAP3DH generate per g;ucose
2 NADH + H+( from NAD)
what are the proofs of the GAPDH mechanism
-phosphate source is inorganic
- hydride is transfereed to NADH to oxidize GAP
what is vitamin B3
nicotinamide (NAD+/ NADP+)
what are the enzymes of vitamin b3
Nad Nadp+
what reaction is vitamin b 3 and what disorder can you get
oxidaton reduction and pellegra
what structure is this
nicotinamide adenine phosphate or dinucleotide
what are the redox cofactors
-FAD= flavin adenine dinucleotide
- FMN= flavin adenine mononucleotide
-NAD
NADP
what do redox factors do
-electron transfer
- energy production
- catabolic and anabolic pathways
energy stored in NADH as what
2 high electron energy that is used to charge the ETC, and make more ATP by OxPhos
why is As (arsenic bad)
it is similar to phosphorous and it can be substituted for P and is poisonous
- As disrupts ATP production
what disrups atp production
As bc it looks like P and it disrups the GAPDH rxn
what functional group from carboxylic acid contains stored chemical energy
anhydrides
a compound with a large negative delta g hydrolysis can transfer what
its phosphate group to a compound with a smaller hydrolysis
what is substrate level phos SLP
production of atp from adp by direct transfer of Pi group ( large negative to smaller less negative)
what compounds form atp through slp
PEP and 1,3 BPG
what happens at PGK step (phosphoglyerate kinase)
first atp generation step meaning SLP
which reactions are thermo and ohysically coupled
GAPDH and PGK
what residue does the phosphoglyerare mutase mechanism have
active form of phosphohistidine in active site
what ec classification is enolase
lyase bc it removes H2O and its reversible bc all lyases are reversibl
why is PEP (phosphoenol pyrivate) the usain bold of high energy compounds
highest standard free energy of hydrolysis due to enol to keto tautomer -61.9Kj/mol
what does the loss of water in 2-PG do
- redistribution of energy
- increasing the hydrolyis making more negative
why is pyruvate kinase or PK important
second atp generation step
what happens in the pyruvate kinase reaction
-metal ion cat
-phosphoryl group transfer
- pep transfers phosphate
what is the net reaction of glycolysis
glucose + 2adp+ 2pi+ 2nad= 2 pyruvate + 2atp+ 2H+ + 2H2O
is glycolyisis anerobic or aerobic
anerobic
what amine is found in aldolase
lysine
used in schiff bases
what is the schiff base
electron sink that stabilizes negative charge
what happens in the aldolase mechanism
- covalent catalysis
-aldolase is a nuc. that forms covalent enz-substrate adduct that alters the reaction pathway
what enzyme has an alternative pathway through formation of a covalent adduct
aldolase
some characteristics of class I aldolase
- cov cat by lys 229
- lys attacks c=o of FBP to form iminium cation - asp 33 is a gen base to cleave c3-c4
- enamine and release GAP
- hydrolysis of iminium cation bc asp 33 also works as a gen acid and pronantes enamine to iminium
where are class II aldolases found
in fungi and algae
- less efficient than class 1
what do class 2 aldolases not form
a schiff base bc a divalent cation Zn+2 polarizes the carbonyl intermediate
does GAP3DH like heavy metals
yes it does because of the cysteine thiol grouos in the active site
what is the GAPDH mechanism
- cys thiol attacks
- thiohemiacetal goes through oxidation to acyl thioester
- nad+ replaces nadh
- inorganic P attacks to form 1,3 BPG
what is the main control point
PFK-1
what is the name of an enzyme that removes or adds phosphoryl group
- phosphatases
- kinases
what is glycongen phosphorylase
control by reversible phosphorylation
what regulaiotn is gly. phos
allosteric bc atp is negative hettero affector and amp is a positive heterotrophic
what has to be regenrated to sistain glycolysis
nad+ thats why pyruvate depends on it
under aerobic conditions what can regenerate nad+
krebs, etc/ oxidative phos
what converts pyruvate to ethanol and co2
yeast and bacteria through alcoholic fementation this also generates Nad+
what cofactor does pyr. decarbox. need for alcoholic ferm
TPP fofactor from vitamin B1
it enables decarboxylation of alpha keto acids
b1 deficiency leads to what
beri beri
-thiamine deficiency
what is a coenzyme
carrier of specific functional groups, come from vitamins
what cofactor does alcoholic dehydrogenase need
Zn+2
ehtanol cant be what
excreted so it has to be metabolised in the liver
- leads to acetaldehye = toxic
homolactic fermentation
- anerobic respiraton
-some bacteria and animal cells
-lactobacillus (yogurt) - pyruvate to lactate
what does ldh catalyze
prochiral differntiation
what is the warburg effect
- malignant tumor cells have glycotic rates that are 200x higher than normal cells
