Exam 1 Flashcards
What is the only non-chiral amino acid?
Glycine
Gly
G
What are the parts of an amino acid?
Amino Group
Carboxylic Group
Hydrogen
Unique side chain
What is the # of possible isomers for a compound?
2^n
n= # of asymmetric C atoms
What type of light do amino acids absorb?
Infrared
Aromatic amino acids absorb UV light (Trp having the highest absorption)
What is optical activity?
The ability to rotate plane polarized light
only Chiral molecules have optical activity
All amino acids in people are in what configuration?
Where does the opposite configuration exist?
L- amino acids
D-amino acids exist in antibiotics, and cell walls in plants and bacteria
Alanine
Ala
A
Arginine
Arg
R
Asparagine
Asn
N
Aspartic Acid
Asp
D
Cysteine
Cys
C
Histidine
His
H
Glycine
Gly
G
Achiral
Inhibitory neurotransmitter
Most common amino acid of collagen
Glutamine
Gln
Q
Glutamic Acid
Glu
E
Isoleucine
Ile
I
Leucine
Leu
L
Lysine
Lys
K
Methionine
Met
M
Phenylalanine
Phe
F
Proline
Pro
P
Serine
Ser
S
Threonine
Thr
T
Tryptophan
Trp
W
Tyrosine
Tyr
Y
Valine
Val
V
What are the amino and carboxylic acid group components when uncharged?
NH2 and COOH
What are the amino and carboxylic acid group components when the pH is neutral?
NH3+
COO-
What are the amino and carboxylic acid group components when the pH is low?
Acidic- amino acid takes up an extra H+
NH3+
COOH
What are the amino and carboxylic acid group components when the pH is high?
Basic- amino acid releases some H+
NH2
COO-
What do amino acids do in response to pH change?
Resist change in pH
What is pKa?
the pH where an ionizable group is 50% ionized
What is the Henderson-Hasselbach equation?
pH = pKa + log [base]/[acid]
What are the nonpolar AA’s?
Alipathic: G, A, V, L, I, P
Aromatic: F
What is a zwitterion?
When the pH is equal to the pI, and there is no net charge
What are the aromatic AA’s
F, Y, W
What are the polar uncharged AA’s?
N, Q, S, T
What are the sulfur containing AA’s
M, C
What are the acidic amino acids? What is their charge?
Negatively charged
D, E
What are the basic amino acids? What is their charge?
Positive
R, K, H
What is special about proline?
It is important for secondary structures
It is an imino acid
Which group of amino acids participate in hydrophobic interactions?
Nonpolar, alipathic AA’s
Where do polar and non-polar amino acids cluster on proteins?
Non-polar’s cluster together in the interior of globular proteins
Polar’s are found on the outside surface of proteins
Maple Syrup Urine Disease is caused by…
A defect in the metabolsim of Nonpolar AA’s
What is the cause of Sickle Cell Disease?
Valine substitutes for glutamic acid in hemoglobin
The valine causes abnormal folding
What amino acid is a large component of ferritin subunits?
Leucine
What group of AA’s participate in H bonding?
Polar uncharged
Which amino acids are important for linking saccharides?
Serine and Threonine
What is the special component of the side chain of tryptophan?
Indole group
Phe and Tyr are precursors for what?
Thyroid hormones
Melanin
Dopamine, Epinephrine and Norepinephrine
What amino acid is very important for signal transduction and enzyme regulation?
Tyrosine
Trp is a precursor for….
Serotonin- mood
Melatonin- circadian rhythm
Niacin- a deficiency causes pellagra
Which amino acids are proton donors?
Acidic amino acids
Found in hydrophilic regions of proteins
What is the most prevalent excitatory neurotransmiter?
Glutamate
What is the most prevalent inhibitory neurotransmitter?
GABA
What amino acid is a major inflammatory mediator?
Histidine
Which amino acid is important for cell division, immune function, hormone release, and ammonia removal?
Arg
Which amino acid is important in nitric oxide synthesis, urea synthesis, and creatine synthesis?
Arg
Which amino acid is responsible for the buffer action of hemoglobin?
His
Which amino acid acid is only essential in children?
His
What are the essential amino acids?
Arg, His, Ile, Leu, Thr, Lys, Met, Phe, Trp, Val
PVT TIM HALL
What is selenocysteine?
A modification of cysteine, found in some redox proteins
Chaperones
Proteins that assist in protein folding
What happens when a protein doesn’t fold correctly?
It will be covalently marked for destruction by ubiquitin, and then they will be directed to the proteasome for destruction
What happens when 2 cysteine residues combine?
It forms a cystine
Primary protein structure
Amino acid sequence
Stabilized by covalent bonds: Peptide and disulfide
How are peptide bonds formed?
Condensation or dehydration reaction
What are the characteristics of a peptide bond?
Partial double bond character
No freedom of rotation
Rigid and planar
Trans bonds usually
AA sequences are read in what direction?
N to C
left to right
How can you identify amino acids?
(What methods)
Chromatography or Mass Spectrometry
How does N-Terminal sequencing work?
Edman degradation
Acid hydrolysis selectively hydrolyzes and then is identified with testing