glycolysis Flashcards
what is the way to harness energy? what bonds do we need to break
CC,CH, COH
in prokkary. where does glycolysis happen
in the cytosol
in euk. where does glycolysis happen
in the cytosol
where does the krebs/etc/ ox phos happen
in the mitochondria
in glycolysis you have to oxidize Cs to what
release energy and capture some of the energy as NADH
use energy in glycolysis to make what compounds
1,3 BPG and PEp
what is the first step in glycolysis and what enzyme is used
glucose turns to G6p with hexokinase enzyme
what is the second step
G6p turns to F6p with phosphoglucoisomerase
all steps involving ATP plus enolase need what
Mg+2
what is the purpose of Mg+2
metal ion cat. (charge shielding)
- cofactor that stabilizes ATP
what is hexokinase
adds a phosphate to glucose and it is highly exergonic
- control point
hexokinase has what type of fit
induced fit
how many calories do carbs have
4 kcal/g
how does Mg+2 aid in metal ion charge sheilding
makes the gamma phosphorous more accessible for nucleophillic attack
enzyme movmen tplaces ATP where
in close proximity to 6’ch2OH and excludes water from the active site
what are some key points about phosphoglucose isomerase
the rxn reversible
GABC
occurs through enediol intermediate
what are the main points of phosphofructokinase
- irreversible meaning you can’t go backwh
what is the main control point
phosphofructokinase 1
what does aldolase do
lyase removes DHap to give a double bond
- the rxn is reversible
what are some main points of triose phosphate isomerase
- reversible
- GABC
- occurs through enediol intermediate
TIM mechanism involves what enediol intermediate
planar transition state analong
what binds to TIM 155 and makes it 100 times stronger than GAP of DHAP
phosphoglycohydroxamate
does equilibirum favor DHAP or GAP
DHAP bc GAP is consumed in the next step this draws the reaction to the right
what does the TIM TPI structure show
alpha beta barrel fold/motif
what structure is this
triosphosphate isomerase
what enzyme generates the first high energy intermediate and what does it use
GAP3DH ( glyceraldehyde-3-phosphate dehydrogenase)
- uses inorganic phosphate Pi
what type of enzymes are redox enxymes
redox enzymes
what transfer do dehygrogenases do
hyride transfer w/ help of a redox factor
GAP3DH or GAPDH generates how many NADH + H+ per glucose
2
how many energy electrons are stored in NADH
2
why is nadh important to the etc
it can charge etc and make more atp by ox phos
what element is similar chemically to phosphorous (P) and can subsitutute for P in biochemical reactions
arsenic
what is the relationship between arsenic and atp
arsenic can disrupt atp productino through several mechanisms
anhydrides contain what
stored chemical energy
what is the first atp generation step
phosphoglycerate kinase
- does substrate level phosphorylation
pgk is similar to what enzyme
hexokinase bc of inducted fit
which reactions are thermodynamically and physically coupled
GAPDH and phosphoglycerate kinase
what residue does phosohoglycerate mutase have in its active site
phosphohistidine phospho-his residue
enolase is classified as what
lyase and its reversible
since enolase is a lyase what does it do
removes H2O to give a DB
what is considered the usain bolt of high energy compounds
phosphoenol pyruvate bc it has a high standard free energy hydrolysis
loss of what from 2-pg causes a redistriubution of energy within pep
loss of water and it increases the delta g hydrolysis of the phosphate form from -16kj to -61.9 kj
what is the secont atp generation step and what does it use
pyruvate kinase , substrate level phos
what happens in the pyruvate kinase reaction
- metal ion cat
- phospho group transfer
- pep transfers high energy phosphate to adp–> atp
- slp
what is the main function of pep
facilitates the generation of atp
what is the net reactants of glycolysis
glucose+ 2ADP+ 2Pi+ 2NAD+
what are the net products of glycolysis
2 pyruvate + 2ATP+ 2NADH+2H+ 2H2O
is glycolysis anaerobic or aerobic
anaerobic meaning there is no O2 involved
what catalysis does aldolase do
covalent catalysis
what is commonly used in formation of schiff bases/imines
lysine
what does aldolase provide
an alternate pathway through formation of a covalent adduct
what residue is a nucleophille in aldolase
lysine 229 it atacks c=o of FBP
what works as a gen base in aldolase
asp 33 to facilitate c3-c4
results in enamine and release of fap
how can asp 33 work as a gen acid
protonates enamine to work iminium cation
the hydrolysis of iminium cation releases what
DHAP
since class 2 aldolases are found in fungi and algae and do not form a schiff base what cation is used
zn+2
is class 2 aldolase less efficient or more efficient than class 1
less efficient
what structures inhibit GAPDH and what does it do to glycolysis
- iodoacetate/ iodoacetamide
- Hg and heavy metals
inhibits glycolysis
what residue does GAPDH have
cysteine thiol groups
in the GAPDH mechanism what acts a nuc and what does it form
cys thiol
forms thio-hemiacetal his as GB
what does thiohemiacetal undergo
oxidation to acyl thioester by direct hydride transfer to NAD+
inorganic Pi attacks what in GAPH
the thioester to form 1,3 BPG
what are the 3 steps that are regulaed in glycolysis
1,3,20
what are the main control points
hexokinase,pfk-1, pyruvate kinase
in a diagram of glucose why is there branching
quick release of glucose units
what are phosphatases
enzymes that remove phosphoryl groups
phosphorylaiton can do what to enzyme activity
activate or inhibit it
glycogen phosphorylase is controleed by what
reversible phosphorylation
what regulation does glycogen phosphorylation have
allosteric regulation
what is a negative heterotropic effector in glycogen phosphorylase
ATP
what is a positive heterotropic effector in glycogen phosphorylase
AMP
what is an allosteric inhibitor
mlcl that binds to an enzyme at a site other than the enzymes active site
even though glycolysis is anerobic what has to be regenerated to sustain glycolysis
NAD+
under aerobic glycolysis what is regenerated
NAD+ by etc/ox phos
why does NAD+ have to be regenrated
for glycolyssis to continue so the fate of pyruvate depends on methods available to cell to do this
what happens under anaerobic conditions
yeast and some bacteria convert pyruvate to ethanol and co2 to regenerate NADH–> NAD+
what is the first step of alcoholic fermentation
pyruvate decarboxylase
what does pyruv. carb. require
thiamine pyrophosphate (TPP) cofactor from vitamin b1(thiamine)
- from vitamin b1 thiamine
what does TPP enable
decarboxylation of alpha keto acids
deficiency in what vitamin leads to beri beri
vitamin b deficiency
what is the purpose of coenzymes
transient carrier of specific functional groups they come from vitamins
alcohol dehydrogenase requires what cofactor
ZN+2 cofactor
since ethanol cannot be excreted it has to be
metabolized by ADH in the liver
what happens if methanol was ingested
liver ADH converts to for,aldehyde
what is the warburg effect
malignant tumors have glycolytic rates that are 200x higher than those of normal cells
what is an isozyme
enzymes with the same reaction but differ in kinetics and regulation
