Exam 1 Flashcards
Amino acids with absorbance at 280 nm
tyr, trp
Amino acid with absorbance at 260 nm
phe
___________ cleaves disulfide bond
2-mercaptoeethanol / BME
__________ prevents re oxidation
iodoacetate
which amino acid can form disulfide bonds
cys
Non polar amino acids (9)
gly, ala, trp, met, pro, ile, leu, val, phe
Polar (-) amino acids (2)
asp, glu
Polar (+) amino acids (3)
lys, his, arg
Polar uncharged amino acids (6)
tyr, gln, asn, cys, thr, ser
Gas phase ions of peptides and proteins are _______ at basic residues to give a positive charge
protonated
Right handed helix turn length
5.4 angstroms
C-C bond length
1.5 angstroms
C-H bond length
1 angstrom
How many atoms are in the amide plane
6
Why aren’t the bonds in the amide plane trigonal planar
because the bond angles are not 120
______ makes hemoglobin lose affinity for oxygen
BPG
Cooperativity
the concept that one hb subunit binding an O2 will cause the other subunits to want to bind an O2 so binding affinity for hb increases
Bohr
high pH = high affinity for R state
low pH = high affinity for T state
Sickle cell is caused by what amino acid substitution
glu -> val
Disulfide isomerase
breaks sulfide bonds to correct errors in amino acid sequence and then helps reform the broken bond
Lysyl oxidase
modifies and cross links collagen side chains
Collagen disorders
Ehlers-Danlos
Scurvy
Osteogenesis imperfecta
Purification used for separating by charge-
ion exchange chromatography
Purification used for separating based on solubility
salting out
Purification used for separating by size
gel filtration chromatography / SDS PAGE
Purification used for separating by binding specificity
affinity chromatography
Which chromatography has a gradient
ion exchange
PITC
modifies N terminus via TFA
Trypsin
cleaves at K and R unless the following amino acid is P
Imidazolium ions
neutral when protonated, negative when deprotonated
Amino acids most likely to be found in a-helix
ala, glu, met
Amino acids most likely to be found in b-pleated sheet
ile, tyr, val
Cyanogen bromide cleaves _____ residue
met
How many amino acid residues per turn of an a-helix
3.6
_________ stabilize collagen helix
covalent cross-links
pH for a buffer must be
comfortably below the pI
Protein with the ______ pI will come out first when using ion exchange chromatography
lowest
If pH > pI the protein will be _____ charged and you should use _______ exchange chromatography
negatively, cation
If pH < pI the protein will be _____ charged and you should use ______ exchange chromatography
positively , anion
Techniques to find protein structure
crystallography, NMR
Scurvy
low levels of vitamin C lead to lower hyp production
Collagen mutations (osteogenesis imperfecta)
any substitution of gly can disrupt collagen formation
Ehlers-Danlos syndrome
Mutation of collagen maturation enzymes
failure to cross-link collagen causes destabilized collagen fibers and hyper-elasticity
