Module 5- Protein

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?

1. HCl acid ‘denatures’

2. 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?

1. peptide chains enter intestine, they still need to be broken down even more

2. the intestine secretes its own active enzyme called intestinal enterokinase

3. the pancreas secretes 2 pre-enzymes into the intestine called trypsinogen and chymotrypsinogen

4. Intestinal enterokinase converts the trypsinogen into its active form called trypsin

5. 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:

6. trypsin activates chymotrypsinogen into chymotrypsin

7. 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?

1. 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.

2. they then get absorbed into intestinal mucosa, that is where they all get broken down into individual AA

3. 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)

4. liver can begin synthesis of AA into required body proteins (enzymes)

5. In a starved person the AA gets immediately used for energy (kcal)

6. 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

1. trypsin activates intestinal pre-peptidases into various peptidases

2. activates chymotrypsinogen into chymotrypsin

3. 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?

1. from the diet (liver→bloodstream)(exogenous)

2. 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