Chapter 2 Protein Flashcards
proteins are linear polymers of ?
amino acids
only (L/D) isomers are used to make proteins
L
L amino acids correspond to the (S/R) configuration
S
At ? pH the amino and carboxyl groups are both charged and make a zwitterion
neutral
only non-chiral amino acid
glycine
has pka near neutral
histidine, pka=6
terminal caboxyl group pka
3.1
terminal amino group pka
8.0
aromatic amino acids
phenylalanine, tyrosine, tryptophan
biological polymers are attached by ? reactions
condensation
Amino acid that can undergo reversible oxidation/reduction reactions to form a disulfide bonds with itself
cysteine
characteristics of peptide bond
partial double bond, resonance, planar (essentially), primarily in trans configuration
x-pro linages
cis peptide bonds are likely with proline
In contrast to the peptide bond, bonds on either side of the ? can rotate
alpha carbon
angle between alpha carbon and amine
phi, -80
angle between alpha carbon and carbonyl
psi, +85
phi and psi frequently called ? angles
Ramachandran
alpha helix and beta sheets are a result of
hydrogen bonding between peptide and carbonyl groups of amino acids that are near one another in a linear sequence
There are ? residues per right hand-turn of the alpha helix
3.6
lactoferrin complexes with ? and chages shape
Fe
Two Human biological buffers
H3PO4^-/H2PO4^2- and H2CO3/HCO3^-
ackalosis
blood ph greater than 7.45
acidosis
blood ph less than 7.35
only cyclic amino acid
proline
functional group in arginine
guanidium
functional group in histidine
imidazole
With ramachandran angles, right handed helix is present in ? quadrant
third, lower left
With ramachandran angles, beta sheet is present in ? quadrant
second, top left
With ramachandran angles, left handed helix is present in ? quadrant
first, top right
coiled-coil protein example
keratins
leucine zipper
heptad repeats of leucine stabilize coiled coil
most abundant protein in mammals
collagen
repeating amino acids in collagen
glycine, proline
collagen structure
triple helix with glycine at interior
“inside out” proteins
porins
motifs
secondary structure elements with characteristic function
? motif is commonly found in proteins that bind to DNA
helix turn helix
a polypeptide chain may fold into two or more compact regions called ?
domains
alpha helix and beta sheets are an example of ? structures
secondary
? and ? can denature proteins
chaotropic agents and reducing reagents
three protein denaturing reducing agents
beta-mercaptoethanol, urea, guanidium chloride
beta-mercaptoethanol disrupts protein folding by ?
bonding with cysteine and breaking disulfide bridges
christian anfinsen experiment
protein folding is an inherent part of AA sequence
CJD, the human equivalent of mad cow disease is caused by a ?
prion protein
? accumulate in alzheimer and parkinson diseases
amyloid fibers
nonpolar AA mnemonic
Larry fought polar vanessa with guns and intricate martial arts
polar AA mnemonic
santa clause quietly tiptoed halfway north yesterday
basin AA mnemonic
knife rally
acidic AA mnemonic
acidic doses of ecstasy