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19 Cards in this Set
- Front
- Back
how can serine be synthesized (2)? what can serine synthesize (4)?
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from glycine or from 3-phosphoglycerate (3 PGA)
can synthesize pyruvate, cysteine, ethanolamine, sphiongosine, and proteins |
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how can glycine be synthesized (2)? what can glycine make?
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made from serine or glycine synthase.
can make purine, heme, creatine, glutathione (GSH), conjugates, and proteins |
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whats so important about GSH?
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its the major sulfahydral compound in the body. is the major reducing agent. protects membranses. keeps proteins in functional states.
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which amino acids are ONLY used for protein synthesis (3)?
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the branch chain amino acids - leucine, isoleucine, and valine
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maple syrup urine disease
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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 |
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what can tyrosine make?
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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
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what are the ketogenic and glucogenic products made by tyrosine?
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acetoacetic acid (acetoacetate) - ketogenic
fumaric acid - glucogenic |
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PKU
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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. |
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Alcaptonuria
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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 |
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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?
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S-AM is used, which is the major methylating afent in the body.
glucocorticoid levels control methyltransferase synthesis |
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what can tryptophan make?
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serotonin (regulates blood pressure and respiration), nicotinamide, alanine, acetoacetate, some niacin production and protein (reversible). tyrptophan is in the lowest concentration.
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which enzymes utilize biopterin/biopterin reductase (3)?
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tyrosine MO, tryptophan MO, phenylalanine MO
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what can methionine make (5) and where does it come from?
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S-AM, spermidine, spermine and cysteine and proteins are what it can make.
it comes from proteins, the diet |
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what can cysteine make (5) and where does it come from?
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it makes protein, cystine, taurine, GSH, and pyruvate
it comes from methionine, and proteins |
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what are the 2 fates of homocyteine?
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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.
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what are the 2 key enzymes of this pathway?
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the synthase and the lyase
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Homocysteinemia
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a defective synthase --> buildup of homocysteine. this is toxic and can lead to cardiovascular disease, lens detachment, fragile bones, and mental retardation.
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Cystathioninemia
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is a defect in the lyase enzyme causing increased levels of cystathionine and therefore increased levels of homocysteine.
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what is related to cardiovascular disease from this pathway and how can these pts be helped?
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increased homocysteine levels are associated with cardiovascular disease, so these patients are given folate, b12, and pyridoxine which can activate the pathway. works sometimes.
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