Proteins Flashcards
The word protein is derived from the Greek word
proteios
The word protein is derived from the Greek word, “proteios” which means
primary
are used for bodybuilding; ____ molecules carry out all the major structural and functional aspects of the body.
protein
Abnormality in protein structure will lead to
molecular diseases
Proteins contain what major elements (4)
carbon
hydrogen
oxygen
nitrogen
minor constituents of protein
sulfur
phosphorus
On average, the nitrogen content of ordinary proteins is __% by weight
16
All proteins are polymers of
amino acids
chain of amino acids bound to one another by peptide bonds
protein
parts of an amino acid (4)
central carbon
carboxylic acid group
amino group
side chain
five amino acids that we can get from food but we can also make ourselves are called what?
also give what are those
non-essential amino acids
alanine
asparagine
aspartic acid
glutamic acid
serine
amino acids that healthy bodies can make them under normal circumstances, but can’t in starvation or certain inborn errors of metabolism (6)
cysteine
arginine
glutamine
glycine
proline
tyrosine
nine amino acids that we can only get from food (what are they called as well)
essential amino acids
histidine
isoleucine
leucine
lysine
methionine
phenylalanine
threonine
tryptophan
valnie
provide essential amino acids that allows the body to produce proteins, hormones, and other important molecules
dietary proteins
process that begin when the food reaches the stomach wherein HCl denatures the protein unfolding it and making the amino acid chain more accessible to enzymatic action
proteolysis
made by gastric chief cells, cleaves any available protein into oligopeptide chains
pepsin
move into the duodenum where a second set of digestive enzymes made by the pancreas further chops these into tripeptides, dipeptides, and individual amino acids
oligopeptides
cells where dipeptides and tripeptides are converted into amino acids
intestinal cells
all nine essential amino acids are provided by what food
animal-based protein
provide high amount of some while low amounts of others are provided in these foods
plant foods
what bridge is formed when an alphacarboxyl group of one amino acid reacts with the alpha amino acid group of another amino acid
CO-NH bridge
synthesized by the polymerization of amino acids through peptide bonds
proteins
two amino acids combined to form a what
dipeptide
three amino acids form a what
tripeptide
four amino acids will form what
tetrapeptide
a few amino acids together will make a what
oligopeptide
combination of 10-50 amino acids forms an
polypeptide
long polypeptide chains containing more than 50 amino acids are called ___
proteins
different levels of structural organization of proteins
primary
secondary
tertiary
quaternary
means the order of amino acids in the polypeptide chain and the location of disulfide bonds, if any
what structure
primary
is the steric relationship of amino acids, close to each other
secondary structure
denotes the overall arrangement and inter-relationship of the various regions, or domains of a single polypeptide chain
tertiary structure
results when the proteins cosist of two or more polypeptide chains held together by non-covalent forces
quaternary structure
the primary structure is maintained by what bonds of the peptide linkages
covalent bonsd
partial double bond
peptide bond
C-N bond is ‘trans’ or ‘cis’
trans
distance between peptide bonds
1.32A
angles of rotation of side chains of the peptide bonds are known as
Ramachandran angles
in a polypeptide chain, at one end there will be one free alpha amino group called
amino terminal (N-terminal) end
amino acid contributing the alpha-amino group is named as what amino acid
first amino acid
the other end of the poylpeptide chain where there is a free alpha carboxyl group
carboxy terminal end (c-terminal)
amino acid residues in polypeptides are named by changing the suffix “-ine” to what
-yl
branching points in the chains may be produced by interchain
disulphide bridges
bond between the disulphide bridges are what kind
covalent
the covalent disulphide bonds between different polypeptide chains in the same protein are called
interchain
covalent disulphide bonds between different polypeptide chains in portions of same polypeptide chain
intrachain
rarely, instead of the alpha COOH group, this part of the glutamic acid may enter into peptide formation
gamma carboxyl
is used to denote such peptide bond formed by carboxyl group, other than that present in alpha position
pseudopeptide
protein in circular form
gramicidin
has two polypeptide chains, a chain of glycine (21 amino acids) b chain of phenylalanine (30 amino acids)
insulin
how many interchain disulfide bonds are there in insulin
two
what cysteine in A chain and B chain are connected
7th and 19th
intrachain disulfide bond between chain a and b is located in what
chain a - 6th and 11th
beta cells of pancreas synthesize insulin as prohormone called
proinsulin
single polypeptide chain with 86 amino acids
proinsulin
biologically active insulin (2 chains) is formed by the removal of what portion of proisulin before release
central
a protein with a specific primary structure will automatically form what shape
three-dimensional
means the spacial relationship of every atom in a molecule
conformation
denotes the spatial relationship between particular atoms
configuration
denotes the configurational relationship between residues, which are about 3-4 amino acids apart in the linear sequence
secondary structure
secondary and tertiary levels of protein structure are preserved by ___
noncovalent forces or bonds
noncovalent forces/bonds in secondary and tertiary structure of proteins
hydrogen bonds
electrostatic bonds
hydrophobic interactions
van der Waals forces
most common and stable conformation for a polypeptide chain (secondary structure)
alpha helix
in proteins like ___ and ____, the alpha helix is abundant
hemoglobin
myoglobin
structure of alpha helix wherein he polypeptide bonds form the back-bone and side chains of amino acids extending outward
spiral structure
alpha structure is stabilized by what bonds between NH and C=O groups of the main chain
hydrogen bonds
alpha-helix is generally left/right handed
right
this configuration of alpha helix is rare, because amino acids found in proteins are of L-variety
left handed
the polypeptide chains in this is almost fully extended, the distance between adjacent amino acids is 3.5A
Beta-Pleated Sheet
stabilized by hydrogen bonds between NH and C=O groups of neighboring polypeptide segments
what secondary structure
beta-pleated sheet
major structural motif in proteins like silk fibroin, flavodoxin, and carbonic anhydrase
beta-pleated sheet
fibroin is parallel/anti-parallel/both?
anti-parallel
flavodoxin is parallel/anti-parallel/both?
parallel
carbonic anhydrase is parallel/anti-parallel/both?
both
may be formed in many proteins in beta-pleated sheet due to the abrupt U-turn folding of the chain
beta bends
what stabilizes beta bends in b-pleated sheet?
intrachain disulfide bridges
denotes three dimensional structure of the whole protein
tertiary structure