Proteins Flashcards
What are proteins?
-Principal organic chemical constituents of body organs and soft tissues
-polymers of amino acids
What are the functions of proteins?
-Membrane structure and transport
-Enzymes
-Regulation of hormones and other signaling factors
-Antibodies
-Structure
What are the classification of proteins?
Globular and Fibrous
What is fibrous?
-structure
-connective tissue
How do transcription and translation play a role in proteins?
-gene to protein
-need enough amino acids to make proteins
-DNA (transcription) -> RNA (Translation) -> Protein
What is the hierarchy of structural classification of proteins?
-Primary
-Secondary
-Tertiary
-Quaternary
What is the structure of a primary protein?
An amino acid sequence.
What is the structure of a secondary protein?
Folding of peptide regions into structures.
What is the structure of a tertiary protein?
Folding of structures into 3D shapes
What is the structure of a quaternary protein?
Multiple proteins interacting as a structure.
What is protein turnover?
-The process or rate of protein degradation
-Its significance: uses energy
-metabolic tissue higher turnover
What is the process of protein turnover?
protein ->protein degradation ->Amino Acid ->Protein Synthesis ->
What is Accretion?
Accumulating body protein
What is Depletion?
Losing body protein
How is accretion achieved?
Net gain pos
What is the structure of an amino acid?
-Amine group (NH2)
-Acid group (CHO2)
-Carbon base (CH)
-R group (side chain) makes each one special
What type of bond does forms protein?
peptide bonds
What happens is water is added to a peptide bond?
It will reverse the process back to 2 amino acids
What is the elemental composition of protein?
-Most of the mass is from carbon
-Nitrogen contributes an important protein
What is typically measured to determine the protein content of feeds?
Nitrogen because it is not in carbohydrates and identifies mostly with proteins.
What is the most typical description of protein composition of a feed?
Crude Protein
What is the average percent of Nitrogen in protein?
16% Nitrogen
-doesn’t apply to all proteins
-depends on the amino acid composition
How can percent N in feeds be measured?
Chemically
How do you calculate crude protein?
6.25 x %N = crude protein
Can you have a feed with over 100% crude protein context?
Yes, because working only with Nitrogen
-Urea 281% crude protein
Do animals have amino acid and protein requirements?
-Animals have amino acid requirements!
-No protein requirements
-some requirements are well defined and others less so
How many main amino acids are there?
20
Wha s an essential amino acid?
-something not made in the body
-need it through diet
Difference between plants and animals when it comes to synthesis of amino acids.
Plants and microorganisms can synthesize all amino acids, but animals cannot and must have dietary source of amino acids
For animals, how many amino acids must be obtained through the diet?
8 must be obtained through the diet out of the 20-25 amino acids in animal tissue.
-All species!
How many essential amino acids are needed for growing pigs?
10
What amino acid do chickens not synthesize?
Glycine, because of this it is considered essential
What are the 10 essentia amino acids?
- Phenylalanine
- Valine
- Threonine
- Tryptophan
- Isoleucine
- Methionine
- Histidine
- Arginine
- Leucine
- Lysine
Do ruminants absorb protein in the rumen?
No, different from carbohydrate absorption, rumen bacteria does get first pass on dietary protein, but protein exits the rumen for digestion by the same mechanisms as non-ruminants.
Process of dietary protein in non-ruminants
dietary protein -> acid stomach -> small intestine
Process of dietary protein in ruminants
dietary protein -> rumen -> acid stomach -> small intestine
Are ruminants and non-ruminants the same once at a certain point?
Yes, once at the acid stomach the process is the same for non-ruminants and ruminants
Does rumen bacteria modify dietary protein?
Yes, it affects the protein structures and uses the protein, but proteins still exit the rumen (some as feed and some as bacteria protein)
Where is the initiation of the acid stomach in non-ruminants, ruminants, and birds?
-Non-ruminants: Stomach
-Ruminants: abomasum (bottom right side)
-Birds: proventriculus
What does the acidic stomach provide?
-acid (HCl)
-proteolytic enzyme: non-specific and chew up anything
-pepsin reduce large polypeptides to smaller polypeptides
What do pancreatic enzymes do?
-continue reduction in the size of polypeptides
-Multiple enzymes secreted into the small intestine
What pancreatic enzymes are secreted into the small intestine?
-Trypsin (cut specific AA)
-Chymotrypsin (cut specific AA) and carboxypeptidases (cleaves carboxy groups)
-Elastase ( cleaves elastoses)
works in acidic pH
What are the end products of pepsin digestion?
Substrates
What is used in protein digestion in the small intestine?
Brush Border Peptidases
What is the process of the Brush Border Peptidase?
- Reduce tetra-peptides and larger to single amino acid and di- and tri-peptides.
- Cleaves single amino acids from ends as well as interior peptide binds depending on the peptidase.
-Examples: endopeptidase (works in the middle)
-aminopeptidase (works on the end)
-carboxypeptidases
-dipeptidases - Many are metalloenzymes (contains metal ion)
Why are peptidases from proline containing peptides difficult for pancreatic enzymes?
Because proline has an amine group shaped in a ring
-enzymes don’t work as effectively
What are the types of transporters for absorption into enterocytes?
-Amino acid transportERS
-Protein transportER
How do Amino Acid TransortERS work?
-Many transporting chemically similar groups of amino acids
-many transporters transporting a single amino acid
-specialization
-Active transport: Gradients (Na, K, Cl) and uses energy through ATP
How does Peptide TransportER work?
-PepT1
-Transport di- and tri- peptides: Two or three amino acid peptides
-Energy through H gradient
-PepT1 no specialization
-transport 2 or 3 at a time
-Efficient!
Why are both amino acid and peptide transport used?
because there might already be single amino acids broken down by the stomach
-further down the GI tract the more likely to have individual amino acids
Where does absorption of amino acids happen?
Small Intestine
What is digestibility?
How much nutritionwe can absorb
Why measure digestibility?
How much is actually being absorbed
How can we measure digestibility?
-Apparent digestibility: Intake - Output = absorbed
-Influence of digestive physiology
What nutrients are easy to measure? and which are challenging to measure?
-Fiber digestibility is easy to measure because we use apparent digestibility
-Amino acids are challenging to measure because in ruminates bacteria from the rumen contain nitrogen and make protein digestibility look higher than it really is.
Do proteins that exist the small intestine be absorbed as amino acids?
No
Does bacteria in the large intestine, containing protein, contribute to amino acid absorption?
No
How are amino acids measured?
Measuring amino acids at the ileum indicates what was absorbed
-true ileum amino acid digestibility reflects disappearance (absorption) of dietary amino acids and accounts or endogenous contributions
-Uses a port/canula
What happens to amino acids after absorption?
Amino acids are released into blood from enterocytes
What vein drains blood from the intestines? and where does it go?
-Portal vein
-blood supply leaving the gut goes to the liver through the portal vein
-blood flows to the liver before returning to the venous circulation
What happens when blood goes through the liver?
-The liver can use and process nutrients from the blood including amino acids and glucose
-The blood than goes onto venous circulation and peripheral tissue
How many pounds are in a short ton?
2,000 Ibs in a shirt ton
How many kg ina metric ton?
1,000 kg in a metric ton
How many pounds in a kg
2.2 Ibs in a kg
Overall process of protein metabolism
- Protein translation: using amino acids for protein synthesis
- Non-essential amino acids: synthesize it
-Essential amino acids: stuck/can’t do anything - Deamination: remove NH2 and produce NH3 (ammonia)
- Detoxify: Urea synthesis
Wat are the potential fates of circulating amino acids after cell uptake?
-Substrate for neurotransmitter synthesis
-Protein synthesis by peripheral tissue
-Amine donor for non-essential amino acids synthesis
-Deamination to provide carbon skeleton donor for gluconeogenesis
-Energy production: Oxidation
What do amino acids used in translation produce?
Proteins with amino acids linked by peptide bonds
Translation from the mRNA transcript
-tRNA binds to matching codon
-the polypeptide is linked to the new amino acid
-mRNA is shifted forward, exposing a new codon
(3 nucleotide codon)
What are the steps in protein translation require energy?
-Amino acid activation
-Initiation of peptide chain formation
-Peptide chain elongation
-Termination of polypeptide synthesis
What is the relative ratio of ATP mols per protein mols?
-5 mol ATP per 1 mol protein
-A mol of protein can be thought of as 100-120g of protein
How many mol ATP per mol protein does amino acid transport require?
Amino acid transport into cells requires approximately 0.5 mol ATP per 1 mol protein is required.
Ratio of mol protein to mol glucose?
1 mol protein to 1 mol glucose
Synthesis of Non-essential amino acid (NEAA)
-making new amino acids from other amino acids and carbon skeleton
-Essential amino acids can provide the amino group needed for the NEAA synthesis
-can also provide carbon skeleton for synthesis of many NEAA
Can all cells and tissues create the amino acids they need?
No, not all cells and tissues can complete conversions
-Some cells or tissues lack a key enzyme for certain amino aids: in combination, tissues have the capacity to synthesize NEAA (EAA donates for NEAA)
What is turnover?
Tissue somewhere amino acid and put into circulation for other to use
What is transamination reaction?
-moving an amino group to make a keto acid
-uses aminotransferase
-Shifting the amino acids we have to make ones we need
What is Deamination?
-removing of an amino group
-produces NH3 (ammonia) and a ketoacid
uses the enzyme L amino acid deaminase (L-AAD)
What are ketoacids? and what happens to them after and deamination?
-caron skeleton
-can be further metabolized in many pathways to produce other products
-products and pathways depend on individual amino group
What should I know about the Kerbs Cycle?
The carbon in an amino acid can be used in many pathways.
What does the Urea cycle do?
Dispose of ammonia
How is ammonia produced?
-Oxidation of amino acids produces NH3
-Ammonia is essential to life for many reactions, but an excess is toxic!
How is ammonia removed?
-urea synthesis by the liver: urea is water soluble and non-toxic, and can be excreted in urine
-Liver removes ammonia from the blood as well as intracellular ammonia produced in the hepatocytes of the liver
Outline of feeding requirements
- Influence on protein requirements
- Nutrient Requirements
-For growth, composition of gain influences requirements
~composition = fat vs lean
-Production also influences requirements - Protein or amino acid requirements
- Feed amino acids supplies
What is the percent of water in lean tissue?
75%
What is the percent water in adipose tissue?
20%
Does the gain of body tissue have different requirments?
Yes, depends on composition
Does lean tissue gain bring in water? how much energy is needed?
-Lean tissue gain brings water with it
-Less energy needed per unit of lean gain because no energy needed for water gain
Does adipose tissue gain bring in water? how much energy is needed?
has less water
-needs more energy per unit of gain
What is needed to make lean tissue?
Protein
What type of tissue do younger animals accrete more of?
Gain more lean tissue (muscle) as a proportion of their body weight
In older animals what is a greater proportion of their body weight gain?
Fat
What is empty body weight?
Body weight with NO organs
On a graph what happens to the body protein line when body weight increases?
The body protein line plateaus with increasing body weight
Is water proportional to protein on a graph?
Yes
Does fat plateau on a graph when body weight increases?
Fat does not plateau
What is missing in a body composition graph?
Missing bone Weight
What do older animals gain more easily?
Fat
How much protein or fat is gain in younger and older animals in 1 kg of gain?
-In older animals 1 kg of gain is mostly fat
-In younger animals 1 kg of gain is mostly protein
What is ADG?
Average daily gain
What is the trend in ADG?
-As weight increases percent amount of protein decreases
-As weight increases percent amount of fat increases
Do protein requirements change in milk production?
As lactation progresses and milk production changes, the protein requirements needed to support milk product changes.
What is the required amino acid concentration for eggs?
-Required amino acid concentration in diet at 80 g/day intake
-At 90% egg production (90 eggs per 100 hens daily)
Ruminant amino acid requirements
-Rumen gets first pass on feeds
-microbes modify and alter amino acid profiles ad they make their proteins
How is important is the amino acid profile of feed in ruminants?
Amino acid profile of feed is not very important because bacteria modifies the protein and makes it the high quality amino acid that is needed.
Do feedstuff proteins have variable amino acid profiles?
Yes, feedstuff have variable amino acid profiles across feed not just protein concentration variation.
What is the protein quality determined by?
Amino acid profile of the feed and the digestibility of the protein.
Do plant proteins used in feed tend do have a EAA deficiency? if so how is this solved?
Yes, Plant proteins tend to have some EAA deficiencies that can be over some using mixtures or with inclusion of animal source protein or amino acid supplements.
Should the protein in feedstuff match the need of the animal?
Yes, they better a protein matches the need of an animal the higher quality of feed it is.
How should you find out soybean amino acid composition?
Refer to analysis of a feed or a table value from a reference
What do microbes in the rumen include?
-bacteria
-protozoa
-some fungi
How do rumen microbes use feed protein?
Use feed protein amino acids to synthesize their own microbial protein including interconversion of amino acids
How does microbial protein compare to requirements?
Take low quality protein and convert them to higher quality/needed amino acids
What is amino acid concentration?
A percentage of total amino acids in rumen bacteria found floating in rumen fluid and bacteria found attached to feed particles in the rumen.
What is considered a good quality for dairy cattle and why?
-Mixed microbial protein
-because of high apparent digestibility and EAA composition similar to that of lean body tissue and milk
What does rumen protein synthesis provide?
At least half of the amino acids for the synthesis of milk and meat in ruminants
