AN SC 260 Ch. 3

building blocks for proteins. Animals require AA not protein. 

All have a common structure (except proline) has a carboxyl group (COO-) and amino group (NH2) and a functional group (R).

300 naturally occuring. 20 found in protein. 10 are essential in the diet depeding on the species.

• Based on the properties of the R group. 
• -Polarity
• -charge (+, neutral, -)
• -hydrophobic vs hydrophillic (determine how proteins will fit in a membrane)
• -branched vs straight

Aliphatic, Aromatic, Heterocyclic, sulfur containing (these are often limiting, methionne, and cysteine), acidic, and basic.

• Based on dietary requirement. 
• -indespensible vs dispensible
• -conditionally indespensible 
• -semi-indespesible 

• can be synthesized from an indespesible precursor. 
• Methionne comes from cysteine
• phenylalanine come from tyrosine 

• Arginine - birds cant make it
• Methionine
• Phenylalanine

• Cysteine
• Glycine
• Proline

• - Arginine in poultry. Needed for maximum growth
• -Proline laying hens. Needed for producing a lot of eggs
• -Glycine in baby chicks
• -Glutamine. Intestinal mucosa during illness

occurs as a free amino acid in cats, and is derived from cysteine

Required in the diet because it is part of heart, skeletal muscles, brain and eyes. 

It is also a major component of bile, antioxidant protection and cardiovascular protection

• - Taurine is naturally in L configuration. 
• - Only the L enantiomer can be absorbed
• -Often a mixture of D,L mixtures

Methionne. The body converts it from D to L enatntiomer 

• -chains of amino acids
• -peptide bonds
• -polypeptides

• -Primary structure, relates to the amino acid order
• -secondary structure, alpha helices, b sheet domains
• -tertiary structure, relationships of domains within a chain, and protein folding (has to do with how the structure bonds to itself. How it folds will determine its function).
• -Quaternary structure, 2 or more polypeptide chains (oligomeric proteins have multiple polypeptide chains held together by non covalent forces)

a squence of a chain of amino acids

occurs when the squence of amino acids are linked by h bonds

occurs when certain attractions are present bewteen alpha helices and pleated sheets

is a protein consisting of more than one amino acid chain

interfere with protein folding which affects protein function

• -size
• -shape
• -chemical compostion
• physical properties
• -solubility
• -biological functions

• -shape
• -solubility
• -other special characteristics

•  Soluble in water, dilute acids or bases, or alcohols
• – Hydrophobic core, hydrophilic external surface (over-simplistic)
• – Functions
• • Enzymes
• • Messengers
• • Transporters

• – Muscle protein
• – Functions
• • Structural proteins in animals – Collagen – toughness in meat
• – Elastin – rubbery; ligaments and arteries
• – Keratins – hair, feathers, horns, hooves

• – Contain non-protein compounds
• • Lipoproteins
• • Glycoproteins
• • Mucus

• Structure
• Movement
• Transport and metabolism

• -collagen ( toughness in meat)
• -elastin (rubbery and ligaments & arteries)
• -keratins (hooves, feathers, horns and hooves

• - Myofibrillar proteins - sacroplasm of muscle
• - contractile proteins - actin, myosin, tyromyosin B 

• -Albumin in blood
• -Enzymes
• -Hormones (insulin, growth hormone, PTH)
• -Antibodies
• -Immune mediators

Right after birth when drinking colostrum 

It denatures protein by disrupting the tertiary structure. It is not necessary for the digestion of protein.

• Very acidic environment. 
• - disrupts tertiary structure (protein folding)
• -Allows access to peptide bonds by pepsin in stomach'
• -endopeptidase, cleaves peptide bonds within the main structure
• -peptide chain broken into smaller chains

• - PH is buffered to neutral
• -Activity of pancreatic proteases
• -peptidases secreted as zymogens ( they are inactive precursors and help prevent self digestion)
• -Entrokinase - secreted by intestinal mucosa and cleaves trypsinogen to trypsin 

MEMORIZE

• Make lots of smaller chains
• Pepsin
• Trypsin
• Chymotrypsin
• Elastase

They come from the end of chains, example is carboxypeptidase

• they cleave specific bonds. 
• -Chymotrypsin - basic amino acids
• -Elastase - small amino acids
• -carboxypeptidase - works at the carboxyl end

• - release of tri and dipeptides, free amino acids in the lumen of the small intestine
• - brush border membrane reduces di and tri-peptides to AA
• -AA absorped 

• - Must be heat treated to prevent trypsin inhibition
• - very good animal feed has lots of amino acids
• -has a trypsin inhibitor which will stop trypsin which will leave lots of long polypeptides lead to digestion ineffeciency 

No protein requirements but needs esssential AA and Nitrogen usaully in the form of protein)

• - Can depend totally on microbial protein synthesis
• - high producing animals may need pre-formed dietary AA

Highest at birth and decline with age. This is related to the growth rate

• -Age
• -Higher in stages of growth then maintenace 
• -Sex dependent usually higher for males
• -Affected by physiological state (gestation, lactation, growth work ect...

yes! Most animals will eat to meet energy requirements so it is important to have protein balanced depending on that 

• – Anorexia
• – Reduced growth
• – Negative N balance
• – Decreased feed efficiency
• – Reduced serum protein
• – Anemia
• – Fatty liver
• – Reduced birth weight
• – Reduced milk production
• – Reduced synthesis of enzymes, hormones

Kwashiorkor- Edema will cause ppl to have extended belly because of fluid buildup in belly.

• "A crop ́s yield is restricted by the lack of a single element, even though there may be sufficient quantities of all other essential nutrients.”

Protein synthesis can only occur untill the limiting AA is used up. Doesnt matter if all other AA acids are in excess. If protein synthesis is defiecent in one AA then the other AA are oxidized leads to fat desposition. Once that limiting AA is replace protein synthesis can continual at optimal level

• - specific lesions. 
• - trypotophan leads to cataracts 
• -thereonone or methionine leads to fatty livers.

Because most feedstuffs are deffecient in at least one amino acid. Example Corn is low in Lys and Trp and Soy is high in Lys and Trp. Thus they will make a good combo

• - Supplement with synthetic amino acids. 
• - D,L-Met, L-Lys, L-Thr, L-Trp available
• - L-Arg, L-Ile on the way

• – Reduction in performance that can be overcome by supplementation of a structurally similar amino acid
• • Effects of lysine excess overcome by supplementation by arginine
• • AA need not be limiting

• – Adverse effects of an AA in excess can not be overcome by supplementation of other AA
• - you have to reformulate the diet

• – The dietary proportions of indispensible AA do not meet the needs of the animal
• • 1 or more AA are limiting
• • Can be overcome by relatively small supplementation of the limiting amino acid or acids