metabolism Flashcards
mitochondria
beta oxidation acetyl CoA production TCA cycle ox phos ketogenesis
cytoplasm
glycolysis fatty acid synthesis HMP shunt protein synthesis (RER) steroid synthesis (SER) cholesterol synthesis
both mito and cyto
heme synthesis
urea cycle
gluconeogenesis
kinase
uses ATP to add phosphate
phosphorylase
adds inorganic phosphate onto substrate w/o ATP
phosphatase
removes phosphate
dehydrogenase
catalyzes oxidation-reductions rxn
hyrdoxylase
adds hydroxyl (-OH)
Carboxylase
transfers CO2 w/help of biotin
mutase
relocates fnx grp w/in molecule
glycolysis rate-limiting step enzyme
phosphofructokinase
gluconeogenesis rate-limiting step enzyme
fructose 1,6 bisphosphatase
TCA cycle rate-limiting step enzyme
isocitrate dehydrogenase
glycogenesis rate-limiting step enzyme
glycogen synthase
glycogenolysis rate-limiting step enzyme
glycogen phosphorylase
HMP shunt rate-limiting step enzyme
carbamoyl phosphatate synthetase
De novo pyrimidine synthesis rate-limiting step enzyme
carbamoyl phosphate synthetase II
de novo purine synthesis rate-limiting step enzyme
glutamine-PRPP amidotransferase
ureas cycle rate-limiting step enzyme
carbamoyl phosphate synthetase I
FA synthesis rate-limiting step enzyme
acetyl-CoA carboxylase (ACC)
FA oxidation rate-limiting step enzyme
carnitine acyltransferase I
ketogenesis
HMG-CoA synthase
Cholesterol synthesis
HMG-CoA reductase
arsenic
glycolysis -> zero net ATP inhibits lipoic acid vomiting rice-water stool garlic breath
NAD
electron acceptor
usually catabolic processes
NADPH
electron acceptor
used in anabolic processes
hexokinase
phosphorylation of glucose - G6P
1st step of glycolysis and glycogen synthesis
expressed in most tissues except liver and beta cells
higher affinity/lower Km then glucokinase
lower capacity/Vmax then glucokinase
not induced by insulin
inhibited by G6P
gene mutation NOT associated w/ MODY
glucokinase
phosphorylation of glucose - G6P 1st step of glycolysis and glycogen synthesis expressed in liver and beta cells lower affinity/higher Km then hexokinase higher capacity/Vmax then hexokinase IS induced by insulin NOT inhibited by G6P gene mutation IS associated w/ MODY
which glycolysis enzymes require ATP?
hexokinase/glucokinase
phosphofructokinase-1 (RLS)
which glycolysis enzymes produce ATP?
phosphoglycerate kinase
pyruvate kinase
fructose 2.6 bisphosphonate
FBPase-2 and PFK-2 are same enzyme whose direction is reversed by phosphorylation via PKA
fasting: increased glucagon -> increased cAMP -> increased PKA -> increased FBPase 2 -> less glycolysis or gluconeogenesis
fed: increased insulin -> decreased cAMP -> decreased PKA -> increased PFK-2 -> more glycolysis and less gluconeogenesis
pyruvate dehydrogenase complex
mito enzyme complex linking glycolysis and TCA cycle (active in fed state)
pyruvate + NAD + CoA -> acetyl CoA + CO2 + NADH
activated by exercise which increases NAD, ADP, and Ca
pyruvate dehydrogenase complex deficiency
x-linked
build-up of pyruvate -> lactate and alanine
neuro defects, lactic acidosis, increased serum alanine starting in infancy
Tx of pyruvate dehydrogenase complex deficiency
increase intake of ketogenic nutrients
high fat
lysine and leucine
pyruvate can become what?
alanine (via ALT for Cahill cycle)
oxaloacetate (via PC for TCA cycle or gluconeogenesis)
acetyl-CoA (via PDH for TCA cycle)
Lactate ( via LDH for Cori Cycle)
TCA cycle
Citrate Is Krebs Starting Substrate For Making Oxaloacetate citrate isocitrate alpha-KG succinyl CoA succinate fumarate malate oxaloacetate
rotenone
blocks complex I of ETC
antimycin A
blocks complex III of ETC
cyanide
blocks complex IV of ETC
CO
blocks complex IV of ETC
Oligomycin
blocks complex V(ATP synthase) of ETC
uncoupling agents
2,4 dinitrophenol
aspirin
thermogenin in brown fat
gluconeogenesis irreversible enzymes
Pathway Produces Fresh Glucose pyruvate carboxylase phosphoenolpyruvate carboxykinase fructose 1,6 bisphosphatase glucose 6 phosphate
pyruvate carboxylase
in mito
pyruvate -> oxaloacetate
phosphoenolpyruvate carboxykinase
in cytosol
oxaloacetate -> phophoenolpyruvate
fructose 1,6 bisphosphatase
in cytosol
fructose 1,6 bisphosphate -> fructose 6 phosphate
glucose 6 phosphatase
in ER
G6P -> glucose
HMP shunt/pentose phosphate pathway
provides source of NADPH from G6P
yields ribose for nucleotide synthesis
NO ATP used or produces
occurs in lactating mammary glands, liver, adrenal Cx
oxidative rxn
use NADP+
create and inhibited by NADPH
produce CO2
irreversible
nonoxidative rxns
reversible
G6PD deficiency
XR MC human enzyme deficiency more prevalent in blacks increases malarial resistance G6PD required to replenish NADPH which is needed for glutathione reductase
G6PD presenation
hemolytic anemia following favao beans, sulfonamides, primaquine, atnituberculosis drugs, or infection
G6PD PBS
heinz bodies- denatured hemoglobin precipitates in RBCs
bite cells- results from phagocytic removal of Heinz bodies
‘Bite into some Heinz ketchup on fava beans’
essential fructosuria
defect in fructokinase- AR
benign asymptomatic condition since fructose not tapped in cells
fructose in blood and urine
fructose intolerance
AR
deficiency of aldolase B
fructose-1-phosphate accumulates -> decreased bioavailability of phosphate -> inhibition of glycogenolysis and gluconeogenesis
urine dip stick neg
symptoms of fructose intolerance
hypoglycemia, jaundice, cirrhosis, vomiting
Tx of fructose intolerance
decrease fructose and sucrose in diet
galactokinase deficiency
galactitol accumulates if galactose in diet
mild
AR
symptoms of glactokinase deficiency
galactose in blood and urine
infantile cataracts
failure to track objects or develop a social smile
classic galactosemia
absence of galactose-1-phosphate uridyltransferase
AR
accumulation of toxic substances in lens of eye
symptoms of classic galatosemia
failure to thrive jaundice hepatomegaly infantile cataracts intellectual disability E. coli sepsis
Tx of classic galactosemia
exclude galactose and lactose from diet