BCAA's have the whole spectrum of branched chain amino acids including essential and non essential acids.
Where as EAA's only contain essential amino acids.
An
essential amino acid for an organism is an
amino acid that cannot be synthesized by the
organism from other available resources, and therefore must be supplied as part of its diet.
Eight
amino acids are generally regarded as essential for humans:
tryptophan,
lysine,
methionine,
phenylalanine,
threonine,
valine,
leucine,
isoleucine. Two others,
histidine and
arginine are essential only in children. A good
mnemonic device for remembering these is "Private Tim Hall", abbreviated as:
PVT TIM HALL.
Which amino acids are essential, varies from species to species, as different metabolisms are able to synthesize different substances. For instance,
taurine (which is not, by strict definition, an amino acid) is essential for
cats, but not for
dogs. Thus, dog food is not nutritionally sufficient for cats, and taurine is added to commercial cat food, but not to dog food.
The distinction between essential and non-essential amino acids is somewhat unclear, as some amino acids can be produced from others. The
sulfur-containing amino acids,
methionine and
homocysteine, can be converted into each other but neither can be synthesized from scratch in humans. Likewise,
cysteine can be made from
homocysteine, but not from scratch. So, for convenience, sulfur-containing amino acids are sometimes considered a single pool of nutritionally-equivalent amino acids. Likewise
arginine,
ornithine, and
citrulline, which are interconvertible by the
urea cycle, are considered a single pool.
Foodstuffs that lack essential amino acids are poor sources of
protein equivalents, as the body tends to
deaminate the amino acids obtained, converting proteins into
fats and
carbohydrates. Therefore, a balance of essential amino acids is necessary for a high degree of
net protein utilization, which is the mass ratio of amino acids converted to proteins to amino acids supplied.
The net protein utilization is profoundly affected by the
limiting amino acid content (the essential amino acid found in the smallest quantity in the foodstuff), and somewhat affected by salvage of essential amino acids in the body. It is therefore a good idea to mix foodstuffs that have different weaknesses in their essential amino acid distributions. This limits the loss of
nitrogen through
deamination and increases overall net protein utilization.
The Amino Acids
(For each amino acid, both the three-letter and single-letter codes are given. CLICK the NAME to see the structural formula)| Alanine | Ala | A | hydrophobic |
|---|
| Arginine | Arg | R | free amino group makes it basic and hydrophilic |
|---|
| Asparagine | Asn | N | carbohydrate can be covalently linked ("N-linked) to its -NH |
|---|
| Aspartic acid | Asp | D | free carboxyl group makes it acidic and hydrophilic |
|---|
| Cysteine | Cys | C | oxidation of their sulfhydryl (-SH) groups link 2 Cys (S-S) |
|---|
| Glutamic acid | Glu | E | free carboxyl group makes it acidic and hydrophilic |
|---|
| Glutamine | Gln | Q | moderately hydrophilic |
|---|
| Glycine | Gly | G | so small it is amphiphilic (can exist in any surroundings) |
|---|
| Histidine | His | H | basic and hydrophilic |
|---|
| Isoleucine | Ile | I | hydrophobic |
|---|
| Leucine | Leu | L | hydrophobic |
|---|
| Lysine | Lys | K | strongly basic and hydrophilic |
|---|
| Methionine | Met | M | hydrophobic |
|---|
| Phenylalanine | Phe | F | very hydrophobic |
|---|
| Proline | Pro | P | causes kinks in the chain |
|---|
| Serine | Ser | S | carbohydrate can be covalently linked ("O-linked") to its -OH |
|---|
| Threonine | Thr | T | carbohydrate can be covalently linked ("O-linked") to its -OH |
|---|
| Tryptophan | Trp | W | scarce in most plant proteins |
|---|
| Tyrosine | Tyr | Y | a phosphate or sulfate group can be covalently attached to its -OH |
|---|
| Valine | Val | V | hydrophobic |
|---|