Proteins Flashcards
1
Q
what is protein
A
- organic compound in food or feed that contains N
- meat, fish, eggs and some plants
2
Q
what do animals require
A
- they require amino acids not proteins
- proteins are made up of the essential amino acids
- if all the amino acids required for the synthesis of animal proteins are not present at the time of protin synthesis, no proteins are made
3
Q
what is the importance of amino acids
A
40% of body protein in skeletal muscle = important for structure or locomotion
4
Q
what are the major functions of amino acids
A
- catalysts
- messengers
- structural elements
- immunoprotectors
- transporters
- buffers
5
Q
what are some major catalyst enzymes
A
- hydrolases - cleaves compounds
- isomerases - transfer atoms in a molecule
- ligases (synthases) - join compounds
- oxidoreductases - transfer electrons
- transferases - moves functional groups
6
Q
whar do enzymes do
A
speed up the rate od reaction
7
Q
what are messengers
A
- hormones
8
Q
what are structural elements
A
- contractile proteins = skeletal muscel (actin/myosin)
- fibrous proteins - keretin, skin, hair, nail strength
9
Q
what are immunoprotectors
A
- immunoproteins (antibiodies)
- identifying antigens and protect body
10
Q
how do proteins act as buffers
A
- amino acids in proteins accept hydrogens when the pH is low
- hydrogen gets bind to amino group and goes from N2 -N3 and pH rises
- amino acids in proteins donate hydrogens when the pH is too high (H ions are released and pH goes down)
11
Q
what do amino acids influence
A
- influence farm animal productivity (growth, production of milk and eggs)
- animal health and fertility ( immunoproteins = animals that are protein defficient will be immuno deficient and more succeptible to disease, ammonia toxicity
- infertility in dairy cows= over feed protein, excesssive ammonia is produced and abosorbed, creating toxic environment
- feeding cost and animal production
- environmental consequences = excretion of nitrogen into the environment (ammonia)
12
Q
what is a basic structure of an amino acid
A
carboxlic
ride chain ( what makes amino acids Different from one another)
amino group (with accepted H atom)
central carbon
13
Q
what is an essential amino acid
A
- body cannot synthesis in adequTE AMOUNTS, so it must be added to the diet
14
Q
non essential amino acid
A
- building blocks are present in the body, can be made and doesnt need to be added in the diet
15
Q
what type of amino acid isomers will be recognized by enzymes
A
L over D
- some D-AA can be converted to L AA (commercial DL - methionine produced by industrial process)
16
Q
what D AA cannot be converted
A
- D - lysine
- lysine produced by fermentation so that only the L isomer is produced
17
Q
what is peptide bonds
A
- AA link together to form peptides
18
Q
what are polypeptides
A
less then or equal to 20
19
Q
what are proteins
A
equal to or greater then 20
20
Q
what is a primary structure
A
- AA sequence
- polypeptide backbones do not differ
21
Q
what is a secondary structure
A
- folding of polypeptide chains into coiled or pleated structures
- determined by what AAs are involed in making protein
22
Q
what is a tertiary structure
A
- 3- dimensional structure of the protein (electrostadic connections)
- strong covalent bonding between cysteine residues - disulfide bridges
23
Q
what is a quaternary structure
A
- assembly of 2 or more different proteins by forces other than covalent bonds
24
Q
what determines protein structure
A
- order of amino acids
- RNA creates genetic cross over that determines protein
- important factor in determining protein nutritional value
25
what does an a helix do for secondary structure
- straight chains of A.A determine the protein content
26
what do B sheets do
- major impact on digestibility
- the more beta sheets there are the more extensive attractions/ bonds limit the acess of enzymes as they are much more folded = making them less digestible
- most sheets are low b sheets except feather meal - feather meal needs to be hydrolysed first for better digestion
27
what are teriary and quaternary strutures more involved with
- more involved with protein functionality than animal nutrition
- keratin and collagen = elastic structure
- hemoglobin = blood oxygen transport
28
what are exogenous sources of proteins
- plant - derived ingredients = soybean, soybean meal, peas, canola meal* and cereal grains
29
what are endogenous proteins
- desquamated mucosal cells
- digestive enzymes, glycoproteins, mucins
- microbes = hind gut, most will be lost in the feces
30
what are the three objectives in protein digestion
- digest dietary protein
- absorb constituent AA
- reclaim digestive enzymes
31
overview of protein digestion
- no digestion in the mouth
- starts in the stomach
- absorbed mostly in the SI - duodenum and jejunum
32
what
33
breaks protein down in the stomach
acid (HCL) and pepsin when it gets activated
- the inactive form of pepsin is pepsinogen
- muscular contractions (peristalsis ) also assist with mechanical break down
34
what happens to the proteins in the stomach
- the proteins need to be denatured to increase the surface area
- HCL does that
- proteins unfold
the stomach pH is 1-2
35
how is protein digested in the small intestine
- acidic chyme enters the small intestine - stimulating enterocytes
- release of pancreatic juice - secretin and CCK
- pro-enzymes, bicarbonate, water and electrolytes are released
pancreatic enzymes are released - trypsinogen(trypsin) chymotrypsinogen (chymotrypsin) procarboxypeptidases A and B (carboxypeptidases A B) proelastase, collagenase
36
what is the difference between endopeptidases and exopeptidases
endopeptidases - digestive polypeptide from the middle
exopeptidases - digestive polypeetide from the ends
37
how are AA and peptides absorbed
- across intestinal brush border memebrane
- AA absorbtion ( through passive diffusion, transporter-dependent absorbtion)
- peptide transport ( >60% of AA absorbed by peptides
Pept 1
H dependent
38
how do endogenous protein losses occur
- mostly enzyme secretion (20-70%) of protein from the diet
- if lost in excess, negative N balance even through dietart protein is adequate
- protease reclamation to reabsorb AA
39
what is a trypsin inhibitor
- changes the shape of trypsin
- protein inhibitor present in many plant products
- causes a significant decrease of protein digestion in monogastrics
- heat labile
40
what is a Tannins
- phenolic compounds that bind, precipitate protein, reduce digestibility
- they are heat labile - destroyed by heat
- reduce solubility and reduce digestion in the small intestine
41
what is a maillard reaction
- free sugars, lysine react in presence of heat, moisture = makes protein less soluable, reduces digestibility
lysine becomes unavailable
- heat decreases protein soluability
42
what are the most used amino acids in the small intestine
- glutamine, glutamate and aspartate
43
how are amino acids absorbed into the extra intestinal tissues
- amino acids enter portal vein to liver
- used by liver ( 50% AA released from portal vein) can be used by other tissues
44
what is the post absorbtion of AA
- plasma AA rise after the meal
- AA pool available for metabolism
- more non essential amino acid in pool
45
what happens during protein takeoever
- continous process of synthesis, degradation (liver, skeletal muscles)
- ks = protein synthesis kd = protein degration
- is ks> kd then protein accretion occurs
- rapidly growing broilers
if kd >ks animals will loose weight
46
why does catabolism of amino acids occur
- normal part of tissue turnover - 20-25% of AA from tissue proteolysis
- disposal of excess(has to be degraded) AA from dietary protein - AA imbalance
- starvation or inadequate CHO, energy intake ( limited CHO - increases AA but lipids are going to be targeted first)
- catabolism states
47
what is a transamination reaction
- amino acids are synthesized
- disposal of access amino acid by taking amonia and turning it into a amino group
48
what is oxidative deamination
- always have the release of free ammonia (always takes place in the liver)
- complete release of amino group as amonia
49
what is ammonia toxicity in famr animals
- extremely toxic to CNS
- ruminants - excessive absorbtion of ammonia from rumen
- non ruminants - excessive protein intake, low arginine diets in monogastrics
-genetic defects in urea cycle
50
what is the urea cycle
- NH3 combines with CO2 or HCO3 to form carbamoyl phosphate
- reacts with ornithine to form citrulline
- aspartate reacts with citrulline to form argininosuccinate
- is cleaved to form fumarate and arginine
- urea is formed and ornithine is reformed from cleavage of arginine
51
what is the fate of urea
- urinary excretion - major form of N secretion
- secretion into the GIT - urea recycling in ruminants
- milk secretion (milk urea- nitrogen)
52
what are the 4 ways the carbon skeleton is used
- the C skeleton from any AA can be used to generate energy for the Kreb Cycle
- for some AA their carbon skeleton can exclusively be used for glucose synthesis through glucogenesis
- any AA whos carbon skeleton end up as Acetly CoA are ketogenic products of a ketone body and fatty acids
- Fourth group of AA that are both glucogenic and ketogenic. their pathways are dependent on animal requirement
53
what is a heat increment
energy lost through evaporation
54
what type of diet is poor in finishing animals
high protein
- want high carbs or high lipids
55
what are amino acid and protein requirements
- common nutrient deficiency ( inadequate protein/AA, energy intake = forces body to catabolize AA) imbalanced AA profile - AA deficiency
- reduces performance = poor growth, poor feed efficiency, negative N balance, low birth weight, low milk production, low egg production
56
what happens to humans with a protein deficiency
energy is adequate
- serum protein is severly decreased (swollen abdomne is present because of the low protein osmotic pressure pulls water out of blood into the tissue
- often occurs in children after weaning in famine areas
57
what is marasmus
- protein and energy malnutrition
- more severe then kwashiorkor
- tissue protein loss is serum protein, liver, then muscle = extremely low body weight
58
what are amino acid requirements of monogastrics
- adequate AA intake for protein accretion, milk production and growing fetus
- maximize lean meat deposition
- protein synthesis is an "all or nothing" event = need correct amounts of proportions to take place
- specicies, genotype, age, level of production, environmental factors
- genetics determine animals capacity for lean meat deposition
- nutrition determines if the genetic capacity is reached
- different genetics have different requirements for AA
59
what are the two major facotrs that effect protein quality
- AA content of protein relative to the requirement of an animal (primary protein structure)
- digestibility of the protein
60
what are the concepts of the first limiting amino acid
- AA supplied in dietary protein in the lowest amount relative to animal requirement
- feed amino acid composition
- animal requirements
- limiting AA determines level of production
61
what is the barrel analogy
- only fill the barrel to the minimum requirement of wine without it spilling
62
what do pigs require for AA
- lysine
63
why does poultry require methionine
- poultry feathers are hight in methionine = they require a larger requirement
64
what are problems with first limiting AA
- takes account of deficiencies but no excesses (excess protein costs energy to metabolize)
- supplimenting first limiting AA may not give optimal growth ( second third are also important)
65
what is the ideal protein concept
- perfect balance of EAA that will meet the requirements for maintenance, production
- lysine is always set at 100% (other EAA expressed as a % of lysine)
- allows for the calculation of the requirement of all AA if lysine requirement is kown
66
advantages of using ideal protein concept
- balanced EAA composition can be fed
- maximum protein accretion and synthesis is supported (maximize growth, reduce days on feed, faster turnover)
- avoid under feeding of AA (maximize growth)
- avoid over feeding of AA (lower cost and less nitrogen excretion)
- can reduce dietary CP requirement
- only need to know the requirement for lysine (everything else you can calculate)
- reduce feed costs, increase profitability
67
why is lysine set to 100 in ideal protein
- usually limiting EAA in cereal - based diets
- no metabolic function other then as a component of protein (lysine requirements can be easily determined (exclusively used for protein synthesis)
- lysine is easy to analyze
- lysine contents of most feeds are well known
68
what are ideal protein ratios
- changes because EAA requirements change
- species, genotype, age, production level, environmental factors
- as pigs grow, EAA req for maintenance, protein deposit changes
69
amino acid requirements
in a growing pig - maintenance requirement is less then production requirement
- EAA requirement mainly determined by the requirement for production (lean deposition)
70
what is total AA vs digestible AA
- % of AA abosorbed in gut differs amount feed ingredients
- diet formulation based on total levels of dietary AA are inaccurate
- practical, usually AA composition of feed ingredients available
71
how do you determine lysine requirement
- provide a basal diet that is adequate for all nutrients other then lysine (basal diet deficienct in lysine)
- add lys-HCl to the basal diet to give different levels of lysine
