subtracted that out from each of the AAs and then fed that new mix which

Subtracted that out from each of the aas and then fed

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subtracted that out from each of the AAs and then fed that new mix which contained different amounts of EAAs compared to eggs. Feeding the new mix led to a 100% BV. - If you add the amount of EAAs in egg protein (mg/g protein) the total is going to be ~50% (so about ½ of all the AAs in eggs are EAAs.) Typically, the amount of essentials in a gram of protein is ~30-35% of the total AAs o Eggs happen to be unusual. Even though egg EAAs are in excess they aren’t the perfect protein for humans. We can ’t handle the excess, it may be a perfect protein for the chick for growth, but it exceeds the needs for humans EFFICIENCY OF PROT UTILIZATION CLOSER TO REQ - It s hard to determine exact requirements b/c the efficiency of utilization of protein as you approach the requirements (0 balance) o The highest efficiency of using dietary protein exists when it’s taken in at low amounts b/c your body will tend to retain and preserve as much as possible. Linearity: as you’re the amount of Leu (doubling it) you get 2x as much being retained until y ou’re approaching N equilibrium. At that point, the efficiency of utilization which means that you have to keep adding more Ile to get to that 0 balance.
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SFLORES_3/24/2014 46 And so the issue among researchers for a long time was: at what point do you say that you’ve reached eq uilibrium? - Re-analysis of old data in the literature shows that researchers by a small amount underestimated the protein requirements of adults and animals (doing best fit and log fit to reanalyze the data resulted in slightly higher amounts) USING LABELED AAs to DETERMINE EAA REQs - N balance studies were used to study EAA reqs for a long time until recently when the labeled tracer AA methods came out. This allowed for the study of protein Q to be applied to studying AA and total N reqs o Repeating old N balance experiments, but using oxidation of a tracer amt of labeled Leu as a way to measure N reqs. (e.g.-Leu) At low amounts of dietary Leu you give a tracer amt of labeled-Leu (this represents all the other Leu molecules in the body) in an otherwise complete diet (all other EAAs and non-essential N, CHO, fat and V&M) everything except the Leu so you’re duplicating the old N balance diet. W hat’s going to happen to oxidation of that Leu you’re feeding? Low levels of oxidation o Remember when fed in low amoun ts in the diet, you’re very efficient at utilizing protein . If you’re efficient at utilizing it, you’re not going to oxidize it If you keep the amount of Leu in the diet, oxidation is going to remain low b/c it’s the limiting AA in the diet so you’re going to keep utilizing it. o Giving more Leu stimulates more protein S = no Leu oxidation When you exceed the req for that EAA, you get max protein syn, and the oxidation rate of the tracer shoots up.
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  • Spring '14
  • Knutson,MitchellD
  • NRG

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