biochem lecture 9 pt 2 Flashcards
another name for pentose phosphate pathway
hexose phosphate shunt
what are products of pentose phosphate pathway
NADPH, ribose-5-phosphate
what is NADPH
pyridine nucleotide used for reductive biosynthesis (fatty acids, cholesterols, nucleic acids)
what else is NADPH important for
elimination of oxygen radicals
what is ribose-5-phosphoate important for
ribonucleotides; RNA, DNA, some coenzymes
what is a major producer of NADPH
pentose phosphate pathway
what is NADPH
a form of reducing power important for biosynthesis reactions like fatty acids, cholesterol, nucleic acids, AAs
what does NADPH serve as a major source of
major source of electrons for formation of synthesis of molecules
what else is nadph important for
elimination of oxygen radicals (reactive oxygen species)
what can oxygen radicals cause
oxidative damage; disease etc.
what else does pentose phosphate pathway do
produces ribose-5-phosphate
what is ribose-5-phosphate
important precursor for ribonucleotide and nucleotide biosynthesis (RNA, DNA, coenzymes)
where does pentose phosphate pathway occur
liver, mammary glands, adrenal glands, adipose tissue
where does pentose phosphate pathway NOT occur
brain and muscle
where in the cell does pentose phosphate pathway occur
cytosol
what are 2 stages of pentose phosphate pathway
oxidative stage and non-oxidative stage
what stage is NADPH produced
oxidative stage
why is the first step of oxidative stage important
because this is where regulation of pentose phosphate pathway occurs
what is first step of pentose phosphate pathway
glucose-6-phosphate –> 6 phosphogluconolactone
what enzyme
glucose-6-phosphate dehydrogenase
what can you do in this first step
regulate this pathway
how can you shut down this pathway
by allosterically inhibiting glucose-6-phosphate dehydrogenase
what step do you generate NADPH
step 1
how many times do you generate NADPH
2 times in oxidative stage
what stage is ribose-5-phosphate produced in
non-oxidative stage
why do we call it oxidative stage
cuz we have oxidation reactions that result in production of NADPH
what is NADPH an important source of
reducing power for reductive biosynthesis pathways
what is ribose-5-phoshpate’s function
precursor for sugars used in DNA and RNA
what do we get overall in pentose phosphate pathway
2 NADPH and ribose-5-phosphate from glucose-6-phosphate
what is the primary site of regulation/control
first step
what enzyme catalyzes the step where we have control
glucose-6-phosphate dehydrogenase
when do we produce 2 NADPHs
oxidative phase
when do we produce ribose-5-phosphate
non-oxidative phase
what does non-oxidative phase involve
convoluted transferase rxns
what enzymes in non-oxidative phase
transketolase and transaldolase
what are the functions of NADPH
biosynthetic pathways, detoxification, reduced glutathione as an antioxidation, generation of neutrophils
what biosynthetic pathways is NADPH involved in
FA synthesis, cholesterol synthesis, steroid synthesis
what detoxification system is NADPH involved in
cytochrome P-450 system
what is cytochrome p-450 system
important in eliminating toxins in diet, and metabolism of drugs
what does cytochrome p-450 system do
involved in how readily drugs are metabolized or inactivated; influences how long they remain effective in our body
what step is regulation of PPP in
glucose-6-p dehydrogenase
what is rate limiting step in PPP
glucose-6-P dehydrogenase
what is an allosteric regulator of glucose-6-p dehydrogenase
NADPH
what is an inducer of glucose-6-p dehydrogenase
insulin
what can both O2 and H2O2 produce
reactive free radical species, damage cell membranes, cause hemolysis
what other enzymes in PPP
glutathione reductase, glutathione peroxidase, superoxide dismutase
what are antioxidant enzymes
superoxide dismutase, glutathione peroxidase, glutathione reductase
what is converted to what in PPP
glucose-6-phosphate –> ribose-5-phosphate
what else is produced in PPP
2 NADPHs
