Levels of protein structure -- Lecture 16 Flashcards
amino acid structure:
parts of amino acid:
central carbon
amino terminal end
carboxyl terminal end
R group
amino acid structure:
what makes an amino acid special?
R group
amino acid structure:
R group (what is it)
variable part of amino acids
give amino acid their individual electrochemical characteristics
4 levels of protein structure (what are they?)
primary
secondary (and super secondary)
tertiary
quaternary
4 levels of protein structure:
primary structure (what is it)
sequence of amino acids in a protein
4 levels of protein structure:
primary structure:
what bonds hold the amino acids together?
what are the 2 ends of the peptide backbone?
peptide bonds
amino end (N-terminus) and carboxyl end (C-terminus)
4 levels of protein structure:
primary structure:
are the R groups part of the peptide backbone?
no
secondary structure:
what causes the protein folding?
folding caused by interactions w/in the peptide bond
secondary structure:
what bonds are present in the secondary structure? How are they formed?
hydrogen bonds form b/n amino hydrogen and carboxyl oxygen atoms
secondary structures:
what are they?
alpha-helix
beta-pleated sheets (consists of 2 or more hydrogen bonded beta-strands)
super secondary structure (how is it formed)
forms when alpha-helices and beta-pleated sheets combine in various ways to form motifs
super secondary structure:
alpha-helices and beta-pleated sheets combine in various ways to form ___
types of ___:
motifs
beta-barrel
beta-alpha-beta unit
protein structure:
all ___ are formed by H-bonding w/in the peptide backbone
secondary structures
protein structure:
all secondary structures are formed by ___ w/in the peptide backbone
H-bonding
protein structure:
all secondary structures are formed by H-bonding w/in the ___
peptide backbone
protein structure:
how do we refer to the entire 3D structure of a folded protein?
tertiary structure
tertiary structure (what is it)
3D shape of the entire protein
tertiary structure is stabilized by interactions b/n the ___ of the amino acids
R groups
stabilizing tertiary structure:
electrostatic interactions:
H-bonds b/n R groups
ionic bonds b/n R groups
stabilizing tertiary structure:
disulfide bridges:
cysteine have a sulfhydryl (SH) group
the SH groups of 2 cysteine residues can form covalent bonds called disulfide (S-S) bridges
stabilizing tertiary structure:
van der Waals interaction:
weak attractive force b/n non-polar molecules due to charge fluctuations in the electron clouds of atoms
stabilizing tertiary structure:
hydrophobic interactions:
hydrophobic (water fearing) R groups will fold to the interior of the protein to avoid contacting w/ aqueous environment
protein domains:
domains are formed from a combination of ___ and ___ interactions
secondary and tertiary
protein domains:
domains are the ___ of a protein
functional subunits
protein domains:
1 protein can contain ___ domains
multiple
examples of protein domains:
DNA binding domains (DBD):
any protein that directly binds to DNA (ex. transcription factors) needs a DNA binding domain
examples of protein domains:
activating transcription of a gene requires a ___ to attract/interact w/ RNA Polymerase
transcriptional activation domain (TAD)
examples of protein domains:
activating transcription of a gene requires a transcriptional activation domain (TAD) to ___
attract/interact w/ RNA Polymerase
examples of protein domains:
the function of a protein is defined by what ___ it has
domain
the highest level of a structure for a single protein is ___ structure
tertiary
quaternary structure (what is it)
the interaction of multiple proteins into multi-protein complexes
quaternary structure:
example and what it consists of
hemoglobin protein in RBC’s
consists of 2 alpha and 2 beta proteins
4 proteins = tetramer
quaternary structure:
hemoglobin function
carries oxygen from the lungs tot eh cells of the body
___ is critical to protein function
proper folding
proper folding is critical to protein function:
chaperone proteins (what they do)
enzymes that help proteins fold and/or refold
they provide an optimal folding environment for other proteins
critical to the proper folding and refolding of most proteins
proper folding is critical to protein function:
misfiled proteins are unable to function properly and are the cause of ___
certain diseases
cystic fibrosis (CF):
what is it
disease in which abnormally thick mucus blocks airways causing difficulty breathing
cystic fibrosis (CF):
the CFTR protein regulates the ___
thickness of mucus
cystic fibrosis (CF):
a mutation in the CFTR gene blocks the interaction b/n the ___ and its ___
CFTR ___ fold properly and is ___ to function
CFTR protein and its chaperone protein
cannot fold properly –> unable to function
