Macro #7 & #8: Proteins and Health Implications Flashcards
Why we need proteins
- Energy
- We need essential amino acids for protein synthesis
- We need certain functional proteins in the body
Recommendations
- 10-35% of our intake
- Important for growth periods
- 70-100g per day
Amino acids
Monomers of proteins (we have 20)
Anatomy of an amino acid
Has
1. An amino group
2. An acid group
Essential amino acids
Cannot be made in the body so we must eat them
Nonessential amino acids
Can be created in the body. Don’t need to eat it
Conditionally essential amino acids
Under certain conditions, the body sometimes can’t make the amino acid so we have to eat it in our diet
Protein Quality
Determined by whether a given dietary protein provides all the necessary essential amino acids in adequate amounts
Complete proteins
Foods that contain adequate amounts of all nine essential amino acids (most animal proteins and some plant proteins are complete)
Incomplete Proteins
Foods that lack one or more of the 9 essential amino acids (grains, wheat, corn, rice, legumes)
Primary protein structure
Chain of amino acids
Secondary protein strucuture
Folding of the chain into either the alpha helix or beta pleated sheet
Tertiary protein structure
Folding of alpha helix and beta pleated sheet
Quaternary protein
Protein consisting of more than one amino acid chain
Peptide bonds
Bonds that keep amino acids together so they can form proteins
Dipeptide chain
Bonding two amino acids
Tripeptide chain
Bonding three amino acids
Polypeptide chain
Several amino acids bonded in a chain
How many proteins can we have coded in our body
~20,000
Functional Protein
Protein that has a specific function in the body
Protein Digestion Part 1
- Protein enters the stomach
- HCL activates pepsinogen and turns it into pepsin
- HCL denatures (unfolds) the protein
- Pepsin breaks down protein into smaller polypeptides
Protein Digestion Part 2
- Polypeptides enter small intestine
- Small intestine releases the hormone cholecystokinin (CCK)
- CCK causes the release of enteropeptidase from the pancreas
What are the pancreatic protease
Trypsinogen
Chymotrypsinogen
Protein Digestion part 3
- Enteropeptidase is released from the enterocytes which contverts trypsinogen and cymotrypsinogen into their active forms: trypsin and chymotrypsin
- Trypsin and cymotripsin break down polypeptides into dipeptides and tripeptides
- Dipeptides and tripeptides are absorbed into the enterocytes
Enteropeptidase
Converts trypsinogen and chymotrypsinogen into their active forms: trypsin and chymotrypsin
Where do amino acids go after traveling through the portal vein?
Amino acid pool
How long do amino acids stay in the amino acid pool
They do not stay long. They enter the pool and then immediately exit to other parts of the body
What percentage of amino acids go from the pool to the liver
70%
What does the liver do with AA
- Synthesis of proteins
- Synthesis of non essential amino acids
- Can oxidize amino acids for energy (turning amino acids into glucose)
- Can convert glucose into fatty acids because it cant be stores in the skeletal muscle once its full so it converts excess to fatty acids and triglycerides
Protein Synthesis
DNA»_space; RNA .. Protein
Transcription and Translation
Transcription
DNA is copied by RNA
Translation
RNA produces amino acid chain by telling the bases what amino acids to produce
Two ways to make new amino acids from old amino acids
Animation
Transanimation
Animation
Adding an ammonium group to an amino group which creates a new amino acid
Transanimation
Transferring an amino group to a different carbon skeleton thats found in the the amino acid pool to create a new amino acid
Where does animation occur?
The liver
Where does transanimation occur?
Cells and blood
Using protein for energy
Gluconeogenesis. Taking protein and breaking it down into amino acids. Amino acids turn into pyruvate which turns into acetyl coa that can enter the krebs cycle
Amino acids turning into pyruvate
Happens in the liver. Removal of the amino nitrogen group from an AA and combing with a different carbon skeleton
What happens of you have too much acetyl coa?
It will turn into triglycerides
Converting glucose into fatty acids
Removing amino/nitrogen group from the amino acid and then converting the excess nitrogen into urine
Urea Cycle
When we remove the nitrogen group to make our new amino acids, we are left with NH4 which is toxic to our body. The liver takes that and converts it into urine to release the nitrogen from the body. Nitrogen increases when protein intake increases
Protein Takeover
Balance between muscle protein synthesis and muscle protein breakdown. Breaking down the proteins we don’t need and building the ones we do
Cancer cachexia
Involuntary skeletal muscle loss or “wasting”
Facts about cancer cachexia
Common in people who have advanced or aggressive cancers
Decreased survival
Decreased efficacy of cancer therapies
Causes weight loss
Loss of skeletal muscle –> loss of balance
Cancer cachexia treatment strategies
Consume higher levels of protein than the normal national average (1.0-1.5 g)
Meet with a dietician
Age-related sarcopenia
Progressive and generalized loss of skeletal muscle mass and strength
Factors affecting normal sarcopenic decline
Anabolic resistance
Decreased protein synthesis
Impaired vascular response
Decreased anabolic hormones
Factors accelerating a punctured decline
Insufficient energy
Protein malnutrition
Interventions for age-related sarcopenia
Physical exercise
Administration of dietary supplements
Target diet
Protein quality
Adequate leucine intake
Timing of protein intake
Protein pacing: consuming protein-containing meals very 3 hours will maximally suppress muscle protein breakdown
How much protein is optimal
1.6-2.2 g/kg/day. Any more than that will create excess calories and acetyl coa will create triglycerides
Leucine
The building block for skeletal muscle proteins and is a signal for protein synthesis to start/ be “switched on”
What happens if you consume large quantities of leucine?
Large amounts of ANY amino acid can saturate our transporters and prevent us from absorbing the other amino acids that we need
Amino acids and carrier proteins
Amino acids compete for carrier proteins. The same type of protein can carry multiple amino acids
