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19 Cards in this Set

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  • Back
how can serine be synthesized (2)? what can serine synthesize (4)?
from glycine or from 3-phosphoglycerate (3 PGA)

can synthesize pyruvate, cysteine, ethanolamine, sphiongosine, and proteins
how can glycine be synthesized (2)? what can glycine make?
made from serine or glycine synthase.

can make purine, heme, creatine, glutathione (GSH), conjugates, and proteins
whats so important about GSH?
its the major sulfahydral compound in the body. is the major reducing agent. protects membranses. keeps proteins in functional states.
which amino acids are ONLY used for protein synthesis (3)?
the branch chain amino acids - leucine, isoleucine, and valine
maple syrup urine disease
inborn error of metabolism where the branch-chained amino acids' dehases responsible for oxidative decarboxylation are not function. leads to a build up of alpha-keto acids in the urine, which leads it to smell like maple syrup.

normally, once the alpha-keto acid is formed, the dehase is supposed to take off a carbon group and add CoA, its an oxidative decarboxylation step. but it doesnt occur in these patients leading to build up of alpha-keto acids, mental retardation
what can tyrosine make?
melanin, biological amines (dopamine, epi, norepi). it is both ketogenic and glucogenic. the pathway to make these compounds its a degradative pathway - getting rid of excess Phe and Tyr
what are the ketogenic and glucogenic products made by tyrosine?
acetoacetic acid (acetoacetate) - ketogenic

fumaric acid - glucogenic
defect in the Phe MO (used to convert Phe to Tyr)
worries about accumulation of phe. diet must be made to exclude phe.
develop lighter skin and hair b/c not as much tyr available for melanin pigmentation.
shortened life span - 50% mortality rate by age 20
excess phe is transaminated to phe pyruvate, which is a phe-keto-compound.
defect in dioxygenase II --> accumulation of homogentistic acid. this gets oxidized when excreted in the urine, changing its color to black. relatively benign.
the acid deposits in joints leading to arthritis
the methyltransferase is used to make epi from norepi in the synthesis of catacholamines using tyrosine. what important compound is used with this enzyme, and what controls its synthesis?
S-AM is used, which is the major methylating afent in the body.

glucocorticoid levels control methyltransferase synthesis
what can tryptophan make?
serotonin (regulates blood pressure and respiration), nicotinamide, alanine, acetoacetate, some niacin production and protein (reversible). tyrptophan is in the lowest concentration.
which enzymes utilize biopterin/biopterin reductase (3)?
tyrosine MO, tryptophan MO, phenylalanine MO
what can methionine make (5) and where does it come from?
S-AM, spermidine, spermine and cysteine and proteins are what it can make.

it comes from proteins, the diet
what can cysteine make (5) and where does it come from?
it makes protein, cystine, taurine, GSH, and pyruvate

it comes from methionine, and proteins
what are the 2 fates of homocyteine?
it can either be converted back to methionine (depends on how much met is already in body) or it can be broken down into propionat3 (propionyl-Coa) via a pathway.
what are the 2 key enzymes of this pathway?
the synthase and the lyase
a defective synthase --> buildup of homocysteine. this is toxic and can lead to cardiovascular disease, lens detachment, fragile bones, and mental retardation.
is a defect in the lyase enzyme causing increased levels of cystathionine and therefore increased levels of homocysteine.
what is related to cardiovascular disease from this pathway and how can these pts be helped?
increased homocysteine levels are associated with cardiovascular disease, so these patients are given folate, b12, and pyridoxine which can activate the pathway. works sometimes.