Protein Metabolism

Front 1

Amino Acid Forms

Back 1

1) L-AA - biological synthesis, including fermentation (yeast, bacteria)
2) D,L-AA - from chemical synthesis get racemic mixture (half D, half L)
3) OH-analogs
4) keto analogs

Front 2

Amino Acid Linkages

Back 2

a. Peptide bond: amino group of AA1 with carboxyl group of AA2
b. N-terminal end: amino group is free
c. C-terminal end: carboxyl group is free
d. Upon hydrolysis (H2O added), free AA are released

Front 3

Globular proteins

Back 3

soluble in water, dilute acids or bases, or alcohol
albumin, globulins, glutelins, prolamines, histones, protamines

Front 4

Fibrous proteins

Back 4

insoluble in water and resistant to digestive enzymes
collagens, elastins, keratins

Front 5

Conjugated proteins

Back 5

lipoproteins, glycoproteins

Front 6

Structural proteins

Back 6

a. collagen - increases with age, makes meat tough, contains lots of proline and hydroxyproline
b. elastin - minor protein, associated with collagen
c. keratins - hair, wool, feathers, hooves, horns, claws, beaks, resistant to dig. enzymes

Front 7

Contractile (myofibrilar) proteins

Back 7

a. actin
b. myosin
c. tropomyosin

Front 8

Blood proteins

Back 8

a. albumins
b. fibrinogen
c. hemoglobin
* most synthesized in liver

Front 9

Metabolic/regulatory proteins

Back 9

a. enzymes - organic catalysts
b. hormones, growth factors
c. membrane proteins, nuclear proteins
d. myoglobin
* most are minor proteins in food

Front 10

Immunoglobulins

Back 10

antibodies, esp. important in colostrum

Front 11

Milk proteins

Back 11

a. casein
b. alpha-lactalbumin

Front 12

How are amino acids stored?

Back 12

96% in protein form and 4% in free form

Front 13

How is protein stored?

Back 13

In skeletal muscle

Skeletal muscle is 20% protein and 80% water

Front 14

Neutral Amino Acids

Back 14

1) glycine (gly)
2) alanine (ala)
3) serine (ser)
4) threonine (thr)
5) leucine (leu)
6) isoleucine (ile, sometimes “iso”)
7) valine (val)

Front 15

Aromatic Amino Acids

Back 15

1) phenylalanine (phe)
2) tyrosine (tyr)
3) tryptophan (trp)

Front 16

Sulfur Containing Amino Acids

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1) cysteine (cys)
2) methinione (met)

Front 17

Acidic Amino Acids

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a. aspartic acid, aspartate (asp)
b. asparagine (asn)
c. glutamic acid, glutamate (glu)
d. glutamine (gln)

Front 18

Basic Amino Acids

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a. histidine (his)
b. arginine (arg) * growth hormone metabolism
c. lysine (lys) * important for birds

Front 19

Imino Acids

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a. proline (pro

Front 20

Other Amino Acids

Back 20

1. hydroxyproline - makes collagen tough
2. taurine - a S-containing AA, not found in proteins, but is a free-AA found only in animal products. It is required for bile acid metabolism and is involved in vision. Especially a concern in cats.
3. ornithine - part of urea cycle, so important for getting rid of extra N
4. citrulline - part of urea cycle, so important for getting rid of extra N
5. cystine - 2 cysteines linked together
- very important in 3d structure of proteins - cross-linking of peptide chains

Front 21

Essential Amino Acids

Back 21

PVT TIM HALL
phe, val, thr, trp, ile, met, his, arg, leu, lys

Front 22

Non-Essential Amino Acids

Back 22

-these are required to make proteins, but they usually can be synthesized in adequate amounts by body tissues
-if you fed only indispensable AA at requirements with no dispensable AA would use lots of indispensable AA to make dispensable AA
-most feeds contain plenty of these
- gly, ala, ser, tyr, cys, asp, asn, glu, gln, pro
- OH-pro, tau, orn, cit, cysteine

Front 23

What is the limiting amino acid concept the basis for?

Back 23

protein quality

Front 24

Who is arg essential for?

Back 24

not essential in adult mammals because of active urea cycle, but is essential in poultry

Front 25

Who is his essential for?

Back 25

essential to young growing mammals, but most adults can synthesize enough

Front 26

What is glycine important for?

Back 26

Feathering

Front 27

What is glycine important for?

Back 27

Feathering

Front 28

Fate of amino acids in blood

Back 28

- incorporated into protein
- catabolized, C skelton used for energy

Front 29

Urea

Back 29

- in mammals
- formed in liver and excreted into urine by kidneys
- Blood Urea Nitrogen: too much can cause fertility issues

Front 30

Proteolysis

Back 30

protein degradation or breakdown

Front 31

Protein Accretion

Back 31

accretion = synthesis - breakdown

growing animal: positive
adult animal: zero
lactating animal: negative

Front 32

Muscle accretion

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Net protein synthesis / 20%

Front 33

%CP

Back 33

6.25 x %N

Front 34

Efficiency of Recovery of Dietary N

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growing animal: 20%
- %50% in young growing poultry

lactating animal: 30%
- never >35%

Front 35

Biological Value

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N retained / N absorbed

high BV: well balanced profile of absorbed AA, low urinary N excretion

low BV: poorly balanced profile of absorbed AA, high urinary N excretion

Front 36

Net Protein Utilization

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BV x digestibility
- considers pattern of available AA relative to requirements

Front 37

Ranking of protein sources (NPU)

Back 37

animal protein, legume leaves, meals of oilseeds, cereal grains, roots and tubers

Front 38

Protein Efficiency Ratio

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body weight gain / protein intake

-used in human nutrition
- legal measurement of protein quality
- only works in growing animals

Front 39

Requirements of Protein relative to energy

Back 39

- decreases with age
- increases with pregnancy/lactation
- doesn't change with excercise
- increases when feeding carb-free diet
- decreases outside thermal neutral zone
- can be lower if feeding to replete body fat in a thin animal
- increases with dietary energy restriction for weight loss

Front 40

Gossypol

Back 40

toxic glycoprotein in cottonseeds, symptoms like vitamin A deficiency

Front 41

Proteinase inhibitor

Back 41

trypsin inhibitor of soybeans, these compounds in seeds prevent protease enzymes from attacking seed proteins until they are needed for growth

Front 42

Urease

Back 42

catalyzes breakdown of urea to ammonia, found in raw soybeans. If mixed in a wet diet with urea, ammonia is produced in the feed and animal will not eat as well

Front 43

Alkaloids

Back 43

toxic heterocyclic N compounds, decrease intake, decrease performance, staggers

Front 44

Tannins

Back 44

polyphenolic compounds that impair palatability and protein availability
- 99% of carcinogenic compounds are naturally-occurring (from Bruce Ames)

- luckily the liver is a great detoxifier and filters these out of the system