Dietary Requirement Method

1) Essential = Any AA that can not be synthesized by the body at a rate that can meet the bodies requirement Þ required in the diet (essential to consume). There are ~10 essential AA.

MATT HILL V.P. or PVT. TIM HALL

P = Phenylalanine

V = Valine

T = Threonine

T = Tryptophan

I = Isoleucine

M = Methionine

H = Histidine

A = Arginine

L = Leucine

L = Lysine

2) Non-Essential = can be synthesized by the body (at an appreciable rate)

1930's: Dr. Rose of Univ. Illinois was first to classify essential vs. non-essential AA. His model was the growing rat.

Exceptions:

Arginine = Adult mammals do not require (growth only)

Glycine = chickens require, feathers and uric acid production

Taurine = essential for the cat

Peptides - covalent bond links AA together. This is called a peptide bond - between the COOH of AA1 and the NH3 of AA2

di- = 2 AA linked together

peptide = usually 3 - 8 AA long

poly- = > 8 AA long

Function: dependent on AA composition

Disulfide Bond: important for maintaining protein structure

Terminal Ends

Glycine = Amino terminal AA

Cysteine = Carboxyl terminal AA

Structure

1^o = the AA sequence of a protein

2^o = involves bonding with disulfide bonds

3^o = 3-D shape - caused by:

1. Hydrophobic AA (Neutral & Aromatic AA) go to inside

2. Hydrophilic AA (Acid/Base) go to outside

¶ Protein function dependant on 3-D structure, 3-D structure dependent on AA sequence, Þ AA determines function

 Denature = irreversible unfolding of a protein

¯ 3-D structure Þ ¯ activity

Methods:

1. Heat

2. Chemical

3. ¯ pH (HCl)