structures of protein Flashcards
the side chain of which amino acids can form hydrogen bonds with asparagine
tyrosine
what is the particular sequence of amino acids of a protein that are joined together by peptide bond called
the primary structure of a protein
strongest type of interaction between side chains of an isoleucine amino acid and a phenylalanine amino acids in a protein
london dispersion forces
strongest type of interaction between 2 cysteine amino acid side chains in a protein
disulfide bond
what type of intramolecular forces exist between the side chains of glutamic acid and lysine
electrostatic attraction
unique structural feature of collagen
triple helix
what is the organic part of heme group called
protoporphyrin IX
true or false:
heme group affects conformation of the polypeptide
true
true or false:
gobular proteins are coiled into compact shapes with hydrophilic outer surfaces that make them water soluble
true
true or false:
the a-carbon and the B-pleated sheet are examples of the tertiary structure of a protein
false - secondary
quaternary structure of proteins
more than 1 polypeptide chain
that chain interact with one another noncovalently
each chain is called subunit
tertiary structure of proteins
noncovalent interactions
backbone H bonding bbtwn polar side chain of aa
hydrophobic interaction btwn nonpolar sidechain
opp charged parts attract e/o
metal ion complexing (iron/zinc)
as central point to organize multiple parts of protein
disulfide bonds – stronger connections btwn aa (cysteines) that can link distant parts of proteins
difference between fibrous and gobular
fibrous
- long and strike like
- not soluble in water
- provide structure n support
gobular
- compact balls
- soluble in water
-functions in cells
it is the first chaperone protein to be discovered
hsp70
*exist in organisms from prokaryotes to humans
it aids in the correct and timely folding of many proteins
protein-folding chaperones
these are major factors in protein folding
hydrophobic interactions
why do folding occur
inside n away from water - non polar hydrophobic side chain
outside n have access to aq enviro - polar side chain
spherical aggregated of lipids arranged so that the polar side head groups are in contact with the water and the non polar tails are sequestered from water
liposomes
unraveling of the 3D of a macromolecule caused by the breakdown of noncovalent interactions
denaturation
denaturation is caused by
heat
large change in pH
detergents (sodium dodecyl sulfate)
urea and guanidine hydrochloride
B-mercaptoethanol
difference between myoglobin and hemoglobin
myoglobin:
stores O2\
bind strongly to O2 at very low pressure
50% at 1 torr partial pressure if O2
hemoglobin:
transport O2
bind strongly to O2 n release easily
100% when O2 pressure is 100 torr
one molecule of myoglobin binds -
hemoglobin can binds up to -
one O2
4 molecules of O2
*binding to hemoglobin = positive cooperativity
tetramer
2 alpha chains (141 residues long)
2 B chains (146 residues long)
a2B2
*myoglobin are homologous
molecules that are made up of smaller subunits (example)
oligomers (dimers, trimers, tetramers)
property of multisubunit proteins such that a conformational change in one subunit induces a drastic change in another subunit
allosteric
- if 1 changes, all the other subunit will change too
pertains to protein that consists of more than one polypeptide chains
quaternary
arrangement of subunits with respect to one another
quaternary
3D arrangement of all atoms in a protein, including those in side chain and in prosthetic groups
tertiary structure
ordered 3D arrangements in space of the backbone atoms in a polypeptide chain
secondary
order in which amino acids are covalently linked tgt
primary
iron-containing cyclic compound
heme
* more than one molecule can bind to heme
it consists of a single polypeptide chain of ____ amino acids and a prosthetic group, ____
myoglobin
153 aa
heme
heme compact structure
a-helical: 8 - stabilized by H bonding
B-pleated sheets: absent
exterior: polar side chains
interior: non polar side chains and 2 histidine
heme group
consists of metal ion, Fe (II)
6 coordination site
forms 6 metal ion complexation bonds
- 4: N atoms of the 4 pyrrole type of porphyrin
-5th: N atoms of the imidazole of histidine
- 6th: O2
protein structure
pri structure (peptide bonds)
sec (H bonding backbone)
tertiary (polypeptide chains)
quaternary (subunits)
gobular protein
non polar - inside
polar - outside
have a-helix and B-sheets
soluble in H2O and salt soln
have compact structures, spherical
contain polypeptide chains organized approx. parallel along a single axis
fibrous protein
*long fibers, strong, insoluble in water and able to dilute to salt soln
all three individual collagen chains are helices that differ from the a-helix
collagen triple helix (tropocollagen)
* held tgt by H bond involving hydroxyproline n hydroxylysine
collagen triple helix
organized in water-insoluble fibers of great strength
repeating sequence of 3 amino acids
repetitive super secondary structures
motifs
common nonrepetitive irregular secondary motif in antiparallel B-sheets
B-bulge
hydrogen bonds btwn peptide chains can be interchain or intrachain
B-pleated sheets
- give rise to zigzag structure n perpendicular to the direction
- polypeptide chain lie adjacent to one another
(same direction - parallel
opp direction - antiparallel)
R groups alternate abv and below plane
stabilized by H bonds parallel to the helix axis within the backbone of a single polypeptide chain
a-Helix
- helical conformation allows linear arrangement
= provide max. bond strength and make conformation stable
true or false:
changes in one amino acid residue in a sequence can alter biological functions
true
biologically active protein are polymers that consist of amino acids liked by what type f bonds
covalent peptide bonds
true or false:
in the absence of bisphosphoglyceate, oxygen binding capacity of Hb wld be lower
false - higher
*BPG supply O2 to the growing fetus
