organization structure of proteins Flashcards
sequencce of amino acids
primary structure
it gives identity to protein
sequence of amino acids
what are the structures?
primary, secondary, tertiary, quaternary
alpha-helix, beta-pleated sheet, triple helix
secondary structure
simple molecules
quaternary structure
how many molecules in hemoglobin
four (2 alpha and 2 beta)
hemoglobin has this structure that binds to what?
hemistructure; iron (gives capacity as oxygen transporter)
it affects other levels of protein structural organization
primary structure
primary structure involves only the ______ linking residues together
covalent bonds
the minimum size of a protein is defined as about ____ residues; smaller chains are referred to simply as _____. So the primary structure of a small protein would consist of a sequence of ____ or so residues
50; peptides; 50
how many molecular weight per residue?
110 Da (daltons)
largest protein discovered has how many residues and daltons/mweight?
30k residues and 3 million Da
insulin has how many amino acids?
51
what is the linkage for cysteine to cysteine?
disulfide linkage
- intramolecular if within one amino only
- intermolecular if with another amino acid
largest known protein
titin or connectin
is found in the striated muscle tissue of humans and other vertebrates
titin or connectin
human titin is >1 µm long and consists of ___ folded protein domains
244
Adults’ bodies contain ≈ __ g of titin.
500g
who identified the sequence of insulin?
frederick sanger
insulin has how many disulfide linkages?
three (1 intra and 2 inter)
what is the structure of insulin?
tertiary structure
the ____ structure of proteins can be characterized as a regular _____ structure held together by _____ bonding between the O of the___ and the H of the ____ groups in the polypeptide chains
secondary; three-dimensional, hydrogen, carbonyl (C=O), amino (NH)
two examples of secondary structure
a-helical and b-pleated-sheet structures
shape or conformation of a protein molecule
tertiary structure
combination of secondary structure
tertiary structure
what are the interactions in tertiary structure?
disulfide bonding
hydrogen bonding
ionic bonding
hydrophobic attractions
known also as the salt-bridge
ionic bonding
positive ionic bonding is
basic amino acids (Arg, Lys, His)
negative ionic bonding
acidic amino acids (aspartic and glutamic acids)
nonpolar amino acids have what
hydrophobic attractions
attraction between negatively and positively charged substituents on the R-groups
ionic bonding
electrostatic attractions between COO- and N+ on acidic and basic side groups
ionic bonding
Can occur between side chains that contain a hydrogen donor
hydrogen bonding
occurs between a residue with an OH or NH and a residue with C = O, COOH, OH or NH
hydrogen bonding
May be intermolecular of intramolecular
hydrogen bonding and disulfide linkage
Can form between the –SH groups of two cysteine amino acids
disulfide linkages
greater attraction than h-bonding
disulfide linkages
Can exist between the Rgroups of nonpolar amino acid residues
hydrophobic attractions
what is the bond in disulfide linkages
covalent bond
a misnomer
hydrogen bonding
in aqueous media, the chain folds so that the hydrophobic side chains face toward the interior, away from the outside environment of polar water molecules
hydrophobic attractions
the hydrophobic groups associate together, strengthening the attractive dispersion forces and minimizing the possibility of a water molecule coming between them
true
hydrogen bonding only occurs in?
O to H
it determines the tertiary structure of insulin
disulfide bonding
to manipulate the tertiary structure of hair protein
redox reaction
loss of hydrogen, loss of electron, gain of oxygen
oxidation
gain of hydrogen, gain of electron, loss of oxygen
reduction
it breaks down disulfide linkages
reducing agent
it binds the disulfide linkages again
oxidizing agent
some complex proteins with two or more polypeptide chains can have what is known as __________
quaternary structure
same forces and bonds that create tertiary structure also hold subunits together (quaternary) in a stable complex to form the _____ protein
complete protein
some proteins are composed of more than one polypeptide chain
quaternary structure
refers to the number and arrangement of the individual polypeptide chains
quaternary structure
each polypeptide is referred to as a ______ of the protein
subunit
_______ is a tetramer containing two pairs of non-identical (but similar) subunits. It has 2 α subunits and 2 β subunits
hemoglobin
substance inside red blood cells that binds to oxygen in the lungs and carries it to the tissues (contains iron)
heme
classify the bonds in each protein structure
primary: covalent bond
secondary: hydrogen bonding
tertiary and quaternary: hydrogen bonding, disulfide linkages, ionic bonding, and/or hydrophobic attraction
are proteins that have a fiber-like shape
fibrous proteins
Fibrous proteins serve as _____ supports and tend to be water ________
structural, insoluble
a fibrous protein found in tendons, ligaments, and bone matrix
collagen
what bond holds a-keratin?
disulfide bonding/linkage
keratin is a ___ protein
fibrous
fibroin forms what?
silk (fibroin is also a fibrous protein)
proteins where the polypeptide chains are folded in a spherical or globular shape
globular proteins
Globular proteins tend to be water ____- and can act as binding agents, enzymes, and as transport vehicles within the ___
soluble, binding agents, enzymes, transport vehicles, blood
what are the four important globular proteins?
carboxypeptidase A, myoglobin, hemoglobin, immunoglobulin G
myoglobin functions as a binding protein carrying _____ for muscle tissue
oxygen
small enzyme that catalyzes protein digestion in the small intestine
carboxypeptidase A
these proteins bind molecules that are foreign to the body, as a defense against disease
immunoglobulin g
heme is a what group?
a prosthetic group
present in proteins that have oxygen
heme
oxygen-hemoglobin binding process, amount of oxygen/s in the cycle
0 1 4 3
0 starting, 1 will add
1 added, 3 more adds (oxygen binding)
4 added, 1 will remove
3 present, 3 will be released
Some proteins contain polypeptide molecules associated with molecules or ions other than polypeptides
conjugated proteins
hemoglobin includes the molecule ____ and the ion ____ in addition to the polypeptide molecule
heme and Fe2+ (iron)
nonpolypeptide molecules are referred as what?
prosthetic groups
proteins containing prosthetic groups are
conjugated proteins
proteins without prosthetic groups are
simple proteins
good cholesterol
high density lipoprotein (lipid carrier)
what are the different classes in conjugated proteins?
glycoprotein, lipoprotein, nucleoprotein, hemoprotein, metalloprotein, phosphoprotein
gamma globulin, mucin, interferon
glycoprotein
hemoglobin, myoglobin
hemoprotein
vldl, ldl, hdl
llipoprotein
fe and zn
metalloprotein
rna-bound protein
nucleoprotein
casein
phosphoprotein
