Tags & Description
What is protein?
constituent “the composition of something” of all living cells
made up of chains of amino acids
What are the essential (we can’t make them) amino acids?
9 essential
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
acronym- History is losing using lying methods focusing three tricking valiantly
peptide
a short chain of amino acids, too small to be considered a protein
how many amino acids are in a protein
around hundreds of them
every AA contains…
nitrogen
what percent of nitrogen are in protein by weight? and how would you calculate
16% nitrogen by weight
protein intake in (g)= N intake (g)x 6.25
why is nitrogen important in protein?
no N in f.a or carbs (protein is the primary source)
need nitrogen for DNA to make sufficient cells to replicate
every amino acid has;
a central carbon
a hydrogen
amino group
acid group
a specific side chain (R)
amino acid; glycine
is it an essential amino acid?
what is its side chain (R)?
non essential- we can make it if we have enough overall protein
side chain- H (hydrogen)
amino acid; methionine
is it an essential amino acid?
what is its side chain (R)?
are legumes a good source of methionine?
Yes it is essential- our body cannot make it on its own
side chain- CH2-CH2-S(ulfer, a mineral)-CH3
legumes are low in methionine
amino acid; phenylalanine
is it an essential amino acid?
what is its side chain (R)?
what is the condition Phenylketonuria? what makes this condition fatal?
yes
side chain- CH2- aspartame(hexagon shaped)
inability to process Phe onto various metabolites, causing excretion through the urine (babies have to get tested)
The build up of Phenylketones become toxic to the brain
Aspartame
two AA linked together w the hexagon shape
tricks the tongue into tasting sweetness
dehydration/condensation reaction
pulling water from the reaction
how does a peptide bond form?
water has to be pulled out as a product through a condensation/dehydration reaction, creating a dipeptide bond (2peptides)
how many peptide bonds in a tripeptide
2 peptide bonds
find the central carbon (will have the side chain(R) connected to it)
amino acids bond to form…
polypeptides
primary structure
linear order of AA
secondary structure
shapes within proteins
tertiary structure
3D shape
Quaternary
3D shapes within other 3D shapes
e.g., hemaglobin
the amino acid _____of a protein determines its final 3-D shape
sequence/order
A protein’s ____is critical to its _____
e.g. Insulin (peptide “protein” hormone)
shape, function
Insulin is made of two AA chains (two polypeptide chains that are interacting)
sulfer containing AA link with another sulfer containing AA on the other chain to form disulfide bridges (the sulfer containing AA are Methionine and /or cystine)
3 disulfide bridges occur
“denature”
heat, acid (HCl in the stomach), base (bleach), that breaks down something
if a polypeptide (insulin, enzyme, antibodies) get denatured what happens
the 3-D shape of the protein gets destroyed
loses its function
how many “proteins” in hemoglobin
4
hemoglobin
what is it and what are the structural components of it?
oxygen-carrying protein in red blood cells
each of the 4 components of hemoglobin contains heme iron (iron held within a ‘cage’, a organic porphryrin ring)
the iron attracts O2 to it and carries it
anemia
reduced oxygen carrying capacity
what happens when there is 1 change in the AA sequence in hemoglobin
the polypeptide shape is altered, the oxygen carrying capacity is reduced, the RBC is sickle shaped, and the condition is called sickle cell anemia
1/5 of our total protein comes from what foods?
meats, dairy products, and grain products
cruciferous vegetables
broccoli, cauliflower, cabbage, brussils, and kale
cruciferous vegetables are a decent source of what? and extremely nutritious in?
protein
vitamin C, fibre, and are full of phytochemicals
Why do we need protein?
category; regulating body processes (hormones, enzymes, and neurotransmitters)
protein based hormones (insulin)
protein based enzy
Why do we need protein? pt. 2
immune defence
→ antibodies: made by B cells
transportation
→hemoglobin- transporting oxygen\
regulates fluid and acid-base balance
→ protein pumps that move molecules across membranes. proteins in blood and within cells act as buffers to prevent change in pH, they do this by controlling hydrogen ions
Energy
→ 4kcal/g, from protein, however your body does not want to prioritize using protein for kcals
what does the statement “protein is the most expensive form of energy”
It requires a lot of energy by the liver and kidneys to use AA as a source of kcals
it takes a lot of energy to make energy
is there protein digestion happening in the mouth?
no
what happens in the stomach during protein digestion and absorption?
HCl acid ‘denatures’
Protein is broke down by an active enzyme into peptides
what active enzyme breaks down protein in the stomach into peptides?
Pepsin
what happens in the intestine during digestion of protein?
peptide chains enter intestine, they still need to be broken down even more
the intestine secretes its own active enzyme called intestinal enterokinase
the pancreas secretes 2 pre-enzymes into the intestine called trypsinogen and chymotrypsinogen
Intestinal enterokinase converts the trypsinogen into its active form called trypsin
Intestinal pre-peptidases (specific cutting enzymes, not active yet) get activated by trypsin into various peptidases that cut/split off AA 1-by-1 from dietary peptides (they go from the ends)
second thing trypsin does:
trypsin activates chymotrypsinogen into chymotrypsin
trypsin along with chymotrypsin cut and split all dietary peptides into smaller and smaller peptides
what happens in the intestine during the absorption of protein?
After the digestion of protein we end up with individual AA and di/tri peptides, because intestine cells actually absorb di-/tri peptides better than individual AA.
they then get absorbed into intestinal mucosa, that is where they all get broken down into individual AA
AA enter blood system via the portal vein. the portal vein heads to the liver
what does the AA do in the liver? (depends on a persons diet)
liver can begin synthesis of AA into required body proteins (enzymes)
In a starved person the AA gets immediately used for energy (kcal)
liver might convert AA→ glucose→ energy for body cells OR (if a person is feasting) the liver will convert glucose into glycogen and store it in the liver OR glucose will be turned into fat and be sent out by VLDL and head out to adipose tissue
why does the pancreas secrete pre-enzymes instead of active enzymes that are ready to work?
if the pancreas held active enzymes, the enzymes would digest the pancreas
what are the 2 pre-enzymes that the pancreas secretes in protein digestion and absorption?
trypsinogen and chymotrypsinogen
what are the 3 things that trypsin does in digestion of protein
trypsin activates intestinal pre-peptidases into various peptidases
activates chymotrypsinogen into chymotrypsin
and it, along with chymotrypsin, cuts up peptide bonds into smaller and smaller chains
what happens when you eat too much of any of the macronutrients?
it will be converted to fat and stored
exogenous
comes from outside the body (from the diet)
where do we get AA from?
from the diet (liver→bloodstream)(exogenous)
from body tissue breakdown (endogenous)”body turnover”
this results in an AA ‘pool’ in cell
why do we call the AA we get a ‘pool’ instead of ‘storage’?
because we don’t store AA, we store them for 20-30min max
what is the #1 priority that the body uses AA for?
synthesis of body protein (enzymes, antibodies, etc)
also lean body mass (muscle) IF the cell requires it
what are the other things the body will do to amino acids besides the #1 priority?
breakdown of AA, called “deamination”
on the chemical formation of the AA the ‘amino side’ gets taken away, so you get free ammonia. Ammonia (NH3) is toxic to the body so the liver converts it to urea and sends it to the kidney for urinary excretion
the ‘c(arbon)-skeleton’ is what is left of the AA after the amino is excreted.
-if you are not getting enough carbs in your diet, the c-skeleton is converted to glucose by a process called gluconeogenesis (creation of glucose)
-used for energy (4kcal/g)
-fat synthesis→stored
what happens to people who have a high protein diet, but their body doesn’t need any for synthesis of body proteins?
it get excreted through urine
Protein quality is determined by;
digestibility of the protein
types of AA (essential AA)
proportion of AA (contains alol essential AA in proportions similar to that required by the body
what % of animal protein is digestible, what about most plant protein?
animal: 90-99% digested
plant: 70-90%, for most plant protein, around 90% for legumes→like soy
what is animal protein considered as? ex)
complete protein
ex) eggs, milk, meat, fish, poultry
what do two complementary proteins equal? and what types of food are they? w ex)
a complete protein, plant based foods (because…..animal based foods are complete protein foods)
grains: low in lysine
legumes: low in met/cys
rice low in ___ and high in Methionine and cysteine is added with _____, low in Met+cys and high in ______ to create a _________ _______
lysine, beans, lysine, complete protein
what kinds of complementary protein foods could a vegan eat?
a lactoveg?
an ovolactoveg?
a pescovegetarian?
an omnivore?
grain, legumes, seeds, nuts
lactoveg- +milk products
ovolactoveg- +egg
Pescovegetarian- +fish
omnivore- +meat, poultry
RDA (recommended dietary allowance) for protein
0.8g/kg/day
how would you convert lbs to kg?
divide lbs by 2.2lbs/kg
the AMDR (DRI) for protein is
10-35% of kcal from protein
what is an exception to the plant based incomplete protein source?
soy
nutrients at risk in vegetarian diets (mainly vegan)
B12- because they are found in animals, so they have to be supplemented
calcium and vitamin D which usually come from milk
Iron and Zinc- because the Iron and Zinc in red meat is more bio-available than in plants
EPA and DHA(alpha-linoleic acid)- because they would usually come from fish, good plant based sources are flaxseed and canola oil
how much protein do we need?
enough where the nitrogen in is = to the nitrogen excreted by our urine
maintain weight
N in> N out
who experience this type of diet?
positive nitrogen balance
gaining body weight (or repairing body tissues)
growth (infants/teens)
pregnancy (fetal growth)
repair (broken leg)
*athletic training but only if additional lean body mass is being gained
N in< N out
who experience this type of diet?
Losing body weight
dieting
famine
disease+burns→repairing tissue and fighting infections
inactive or weightless (astronaut)
infants need more protein than adults because..
they are rapidly growing
the most commonly demographic of people who have insufficient protein intake are….
elderly women
Atwater factor for protein?
__kcal/gram of protein
atwater factor- 4
4kcal/gram of protein
why should you avoid amino acid supplements in regards to your GI tract? explanation
if you were to take an amino acid supplement for Pheynelinine then all your receptors that carry AA in the blood stream will be filled with Phe and other AA will not be absorbed like Tryptophan and Tyrosine
why should you avoid amino acid supplements in regards to your brain? explanation
if there is only Phe, as an example, coming from the bloodstream into the brain. The brain will find it hard to find certain AA to make certain protein neurotransmitters.
For example less tryptophan to produce serotonin
why should you avoid amino acid supplements in regards to your brain and GI tract? resulting risk
AA imbalance
Mood disorders
what did they find when feeding babies individual AA formula? What is the bottom-line message?
the nitrogen retention was not as good compared to food also they found that they weren’t absorbing the AA as good as in food even though they were individual AA
get protein from food
What are the major factors when you eat above total daily kcal for protein?
increased energy intake→ you are just eating too much
high protein foods are high in fat (9kcal/g), esp. Sat fat→contributed with heart disease
high animal protein intake increases calcium loss from body→osteoperosis. Because specific AA have S attatched to them which uses Ca from bone to buffer their acidity, but eating it with milk of F+V can reduce Ca loss
people with renal (kidney disease). Their kidneys are already damaged so why would you give them more work to do for nothing, especially plp w type 2 diabetes have to be careful with their protein intake
Cancer: excess/high intake of red meat/processed (deli meat). animal pro feeds evil microbes and the by-products are TMAO which are cancer promoters. meanwhile lean+plant pro feed healthy microbes