Protein Metabolism Part 1 W7 Flashcards
When do conditionally non-essential amino acids become conditionally essential?
Pregnancy
Patients with PKU (Phenylketonuria)
What is the main site of protein synthesis?
Liver
What are amino acids precursors and regulators for?
Synthesis of body proteins (precursor only)
Neurotransmitters
Hormones
DNA
RNA
How can you measure protein loss?
Sweat
Skin
Hair
Urine
Faeces
What does the liver generate as an energy substrate and then metabolised endogenously in the liver?
Ammonia (this is converted into urine)
How much nitrogen is in 1g of protein?
6.25g
What is nitrogen (protein) balance?
What goes in must eventually come out
What does the side chain of an amino acid allow?
Allows us to determine structure
How do you calculate nitrogen balance?
1) Determine nitrogen excretion
2) Determine nitrogen intake
3) N Balance (2-1)
Nitrogen intake- Nitrogen Excretion
How do you determine nitrogen excretion?
In grams per 24hr period
How do you determine nitrogen intake?
Protein intake (g) divided by 6.25
What does determining the N balance for protein allow?
Estimation of the required protein intake needed to maintain protein balance
What is the protein reference nutrient intake (RNI)?
0.75 g/kg/d
What are the limitations of nitrogen balance?
No information of tissues
Lack of sensitivity (gross measures of intake and excretion)
Zero balance on low intake my reflect accommodation
Positive balance may not relate to lean body mass
How is net protein balance calculated?
Protein synthesis - protein breakdown
How much of your total body mass does skeletal muscle tissue make up?
40%
What has a greatest protein turnover rate, skeletal muscle or the gut?
Gut
How much of protein is nitrogen?
16%
What is nitrogen balance adequate in measuring?
Measuring amino acids required to prevent “deficiency”
What is nitrogen balance inadequate in measuring?
Estimating the amino acid requirements for exercise-induced muscle remodelling
What is MPS?
Muscle Protein Synthesis
What is MPB?
Muscle Protein Breakdown
What does a + net protein balance indicate?
Protein accretion
What does a - net protein balance indicate?
Protein loss
Is nitrogen balance a good indicator of muscle protein balance?
No
What is the RDA for protein?
0.8g/kg/bw
What is the sufficiency of the RDA and RNI estimations of meeting the overall population?
97%
When is net muscle protein balance at its greatest?
Following exercise training and ingestion
In the post-exercise period, the MPS response to protein ingestion is enhanced. How long does this enhanced response last for?
24-48 hours
