Quiz 2 Flashcards
Nonessential
Synthesized in the body; Alanine Asparagine Aspartate Glutamate Serine
Conditional Essential
Synthesis can be limited under special pathophysiological conditions (prematurity of infants or those with severe catabolic distress) Arginine Cysteine Glutamine Glycine Proline Tyrosine
Essential
Indispensible aa; can't be synthesized de non so must be supplied by diet Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Threonine Tryptophan Valine
ketogenic
AA that are converted to acetyl CoA or acetoacetate so precursors of FA and ketone bodies
Glucogenic
AA converted to precursors for glucose synthesis like alpha ketogluterate, succinyl coA, fumerate, pyruvate, oxaloacetate
Both ketogenic and glucogenic
Isoleucine, Phenylalanine, Tyrosine, Tryptophan, Threonine
Stereoisomerism in alpha- AA
L and D configurations ; most in nature are L
AA are all chiral except glycine (enantiomers)
Nonpolar, aliphatic R groups
Glycine, Alanine, Proline, Valine, Leucine, Isoleucine, Methionine
Aromatic R groups
Relatively nonpolar; absorb UV (Tryptophan absorbs most followed by tyrosine the Ph)
Tryptophan, Phenylalanine, Tyrosine
Polar, uncharged R groups
Serine, Threonine, Cysteine, Asparagine, Glutamine
Positively Charged R groups
Lysine, Arginine, Histidine
Negatively charged R groups
Aspartate, Glutamate
Reversible formation of a disulfide bond by the oxidation of 2 cysteine
Hair straightening (safer; most representative aa in hair)
Uncommon amino acids/ modifications of aa
Hydroxyproline and hydroxylysine found in collagen
Addition of phosphate, methyl, adenosine (reversible)
AA not found in proteins
Ornithine (urea cycle, bad breath) and citrulline (byproduct of production of nitric oxide- vasodilator)
Non-ionic or zwitterion forms of AA
Zwitterion- neutral molecules with a positive and negative electrical charge though multiple positive and negative charges can be present
a characteristic pH, called the isoelectric point (pI), the negatively and positively charged molecular species are present in equal concentration; characteristic pH at which the net electric charge is zero
Effects of chemical environments on pka
pka -COOH 1.8-2.4 [4.8?]
pka -NH3 8.8-9.7 [10.6]
isoelectric pt: 5.5-6.2
Titration of amino acids
pI=1/2 (pka1+pka2) of the pkas closest to each other? (+1, -1)
Proteins are polymers built from aa joined by peptide bonds
usually peptides- have ~50 or fewere AA vs proteins (1 or more polypeptide)
Formation of peptide bond by condensation
Removal of water (OH from carboxy and H from amine)
AA residues; not rotatable around peptide bond but can rotate around alpha carbon
As increase residues, increase of MW
Conjugated proteins
Lipoproteins, Glycoproteins, phosphoproteins, hemoproteins, Flavoproteins, metalloproteins
Levels of structure in proteins
Primary (aa string), secondary (alpha helix or beta pleated sheets; H bonds), tertiary (folding; polypeptide chain) quaternary (assembled subunits)
A change of a single aa can alter the function of protein
Ex. sickle cell anemia Glu–> Val
Collagen Synthesis
Need vitamin C (not enough OH without it- can’t attain full strength)
Hydroxyproline and hydroxylysine found in collagen
Diseases related to collagen
Scurvy, Osteogenesis imperfecta, Ehlers- Danlos Syndrome, Spondylopiphyseal Dyplasia