BIOCHEM 2.1: Chemical Structure and Properties of Amino Acids

Peptide bond

Amino group attaches to carboxyl group of another AA

Property of amino acid that acts as both acid and base vital im the formation of peptide bond

Ampotheric

Zwitterion

Molecule that carries both positive and negative charge making it electro neutral overall.

Aromatic rings

Functional groups responsible for UV absorption.

Alanine

R: Methyl group.

Used to breakdown tryptophan and Vit B6

Valine

R: Isopropyl group

precursor in biosynthetic pathway of penicillin

Leucine

R: Isobutyl

Isoleucine

R: Secbutyl

Oxygen carrying pigment inside the RBC

Proline

R: Imino Acid

Only proteinogenic secondary imino acid.

Blue/Blue purple on Isatin Test

Methionine

R: thioether (R-S-R)

Sulfur containing

Precursor for Succinyl CoA

Serine

R: Hydroxymethyl (alcohol group)

Cycloserine (antituberculosis)

Threonine

R: Hydroxyethyl (alcohol group)

Substrate for mucin

Asparagine

R: amide group

breakdown of ammonia

Glutamine

R: amide group

Produce glutathione

Cysteine

R: Thiol group (-SH)

Black on Lead Acetate test

Glycine

R: H

Neurotransmitter in CNS

Aspartate

R: Carboxyl group

Glutamate

R: Carboxymethyl group

Precursor of GABA

Arginine

R: Guanido group

(+) Sakaguchi test

Precursor of nitric oxide

Histidine

R: Imidazole group

Involved in the synthesis of oxygen

Precursor to histamine

Lysine

R: Amide group

Phenylalanine

R: Benzyl

Precursor for tyrosine

Tyrosine

R: Phenol

Precursor for neurotransmitters such as Epi, NE, dopamine

Tryptophan

R: Indole

Precursor to serotonin and Melatonin

Derived amino acids

Group of AA that are not directly incorporated into proteins.

Typically from modification or transformations of standard AA

Hydroxyproline and hydroxylysine

Commonly foundin collagen

Hydroxylysine

Used in making lysine (cross-linking of collagen)

Gamma-Aminobutyric Acid (GABA)

Derived from glutamate. Inhibitory neurotransmitter signaling between nerve cells.

Orthinine

Derived from arginine

Citrulline

Intermediate in urea cycle

Carnosine and Anserine

Derived from histidine and beta alanine and have antioxidant and buffering properties and buffering properties.

5-Hydroxytryptophan

Derived from tryptophan precursor to serotinin

Leucine and Lycine

“LeuLy”

Purely Ketogenic

“PIso TTy”

Phenylalanine

Isoleucine

Tryptophan

Tyrosine

Ketogenic and Glucogenic

“PVT TIM HALL”

Phenylalanine

Valine

Threonine

Tryptophan

Isoleucine

Methionine

Histidine

Arginine

Leucine

Lycine

Essential Amino acids

Arginine and Histidine

Partially essential amino acid

Condensation

“Dehydrate to build, hydrate to break it to you”

Formation of peptide bond

Oxidation

Amino group is removed resulting to the production od ammonia and a keto acid.

Transamination

Transfer of amino acid to a keto acid generating a new amino acid and a different keto acid

Decarboxylation

Removal of carboxyl group.

Ex: Histidine —→ Histamine

Hydrolysis

Breaking of the peptide bond. Important fir protein digestion in the stomach and small intestine.

Homoarginine

Implicated in human neurolathyrism.

Cleaved by arginase to L-lysine and urea

β-N—Oxalyl diaminopropionic acid (β-ODAP)

Found in grass pea (Lathyrus sativus)

Cause lathyrism

Β-N-Glutamylamino-propiononitrile (BAPN)

Known as osteolathyrogen. Inhibit the enzyme responsible for corss-linking collagen and elastin fibers in connective tissue.

.2-4-Diaminobutyric Acid (DAB)

Involved in the synthesis of antibiotics like bacitracin.

Inhibit ornithine transcarbamylase, resulting in ammonia accumulation, hence toxicity.

Β-Methylaminoalanine (BMAA)

Structurally similar to alanine but contains a methyl group and an amino group in a beta position, making it distinct from standard amino acids