Proteins Dash 3 (Part 2) Flashcards
Experiments have
shown that the final
3D tertiary structure
of a protein ultimately
is determined by the
Primary structure (amino acid sequences)
The 3D fold (shape) of
the protein determines
its .
function
The primary structure of a
protein refers to its
Amino acid sequence
Amino acids in peptides ( — aas) and proteins (typically —- to —– aas) are joined together by peptide bonds (amide bonds) between the carboxyl and amino groups of adjacent amino
acids.
<30 aas
200 to 1,000
Only the R-group side-chains vary. By
convention, protein sequences are
written from left-to-right, from
the proteins ——–
N- to C-terminus.
The average yeast protein
contains how many amino acids?
466
molecular weight of an amino acid is — daltons (Da), the average
molecular weight of a yeast
protein is 52,728 Da. Note that
1 Da = 1 a.m.u. (1 proton mass).
113
refers to short-range, periodic folding
elements that are common in proteins.
Secondary Structure
Secondary structure includes the
a-helix and b sheet and in turns
In the α helix (Fig. 3.4), the backbone
adopts a ——- —– structure
in which there are 3.6 aas per
turn.
Cylindrical spiral
The α helix is stabilized by ??? between backbone carbonyl oxygen and amide nitrogen atoms that are oriented ??? to the helix axis.
H-bonds
parallel
H-bonds occur between residues located in the n and —- positions relative to one another.
n + 4
In β sheets (a.k.a. “???? ???? ”), each β strand adopts an ?????
pleated sheets
Extended conformation
ß strands tend to occur in
pairs or multiple copies in β
sheets that interact with one
another via —— directed
——
to the axis of each
strand.
H-bonds
Perpendicular
Strands can orient ———— or —— to one another in β sheets
Antiparallel or parallel
ß Turns consist of 3-4 amino acids
that form
tight bends
Longer connecting
segments between ß strands are called
Loops
refers to the
folded 3D structure of a protein
Tertiary Structure
Tertiary structure is also known as the —— structure or —— ——-
Native structure or active conformation
Tertiary structure mostly is
stabilized by ——— ——- between secondary structure elements and other internal sequence regions that
cannot be classified as a particular
type of secondary structure.
noncovalent
interactions
The structures of
hundreds of proteins have been
determined by techniques such as
x-ray crystallography and NMR.
are evolutionarily conserved collections of secondary structure elements which have a ——
conformation. They also have a ——- sequence because the aa sequence ultimately determines structure.
Secondary structure motifs
Defined
Consensus
Multisubunit (multimeric)
proteins have another level
of structural organization
known as —— ——-.
Quaternary Structure
refers to the
number of subunits, their
relative positions, and
contacts between the
individual monomers in a
multimeric protein
Quaternary
structure
independently folding and functionally specialized tertiary structure units within a protein.
Domains
The modular domain structure of many proteins has resulted from the ——– and ——- together
of their coding sequences within longer genes.
shuffling and splicing
multimeric proteins
achieve extremely large sizes,
e.g., of subunits
10s-100s
Such complexes exhibit the highest level of structural organization known as
Supramolecular structure
Typically,
supramolecular complexes function
as “——– ——–” in
reference to the fact that the
activities of individual subunits are
coordinated in the performance of
some overall task
macromolecular machines
Through ——- ——- and ——– —– —-
approaches, the sequences
of an enormous number of
proteins have been compiled.
Genome sequencing and classical gene cloning
Proteins that have a common
ancestor are called
Homologs
These —– proteins are composed of mostly α helical
secondary structure
Globular
