protein Flashcards
Peptides and proteins are formed when amino acids are joined together by
amide bonds
has two amino acids joined together by one amide bond
dipeptide
The amide bond is called a
peptide bond
have many amino acids, while proteins is usually reserved for polymers of > 40 amino acids.
Polypeptides
The amino acid with the free –NH3+ group is the N-terminal amino acid and is written on the?
left
The amino acid with the free –COO− group is the C-terminal amino acid and is written on the?
right
pentapeptides synthesized in the brain act as pain killers and sedatives by binding to pain receptors
Enkephalins
Enkephalins has two types
Met- enkephalin and leu-enkephalin
contains amino acid that blocks pain and are thought to produce the feeling of well being experienced by an athlete after excessive or strenuous exercise
Endorphins
are cyclic nonapeptide hormones secreted by the pituitary gland. They are identical in structure except for two amino acids
Oxytocin and Vasopressin
Biological Functions of Proteins
Enzymatic catalysis
Transport Proteins
Nutrient Proteins
Storage Proteins
Contractile Proteins
Structural Proteins (Collagen, Elastin, Keratin, Fibrin)
Defense Proteins (Antibodies, Prothrombin and
fibrinogen)
Regulatory Proteins
Simple Proteins
Albumin
Globulins
Glutelins
Prolamines
Scleroproteins of Albuminoids
Histones
Protamines
regulate ADH
vasopressin
enzymes in lactation
oxytocin
Conjugated Proteins
Nucleoproteins
Glycoproteins and mucoproteins
Phosphoteins
Chromoproteins
Lipoproteins
Metalloproteins
for clot formation
fibrin
part of clotting
prothrombin
produce by plasma cells
antibodies
transport nutrition
albumin
regulates cholesterol
lipoproteins
Proteins
Metaproteins
Coagulate Proteins
Primary Derived Proteins
Proteases
Peptones
Peptines
Secondarily derived Proteins
The ____ of a protein is the sequence of amino acids joined together by peptide bonds
primary structure
is the 3D arrangement of localized regions of a
protein.
secondary structure
These regions arise due to hydrogen bonding between the N—H group
of one amide with the C═O group of another
Secondary Structure
is the 3D shape adopted by the entire peptide chain
tertiary structure
Maximize Hydrogen bonding with water (hydrophilic)
tertiary structure
Stabilize non-polar sidechains by london dispersion forces
(hydrophobic)
tertiary structure
Polar functional groups H-bond with each other
tertiary structure
Charged sidechains attracted through electrostatic interactions and disulfide bonds form
tertiary structure
The ____ of the protein is the shape adopted when two or more folded poly-peptide chains come together into one complex
quaternary structure
bad cholesterol
LOW DENSITY LIPOPROTEIN
GOOD CHOLESTEROL
HIGH DENSITY LIPOPROTEIN
part of hemoglobin metabolism that toxic in body
billirubin
cause by a yellowish in skin
billirubin
billi in blood
jaundice
Bonds Responsible for Protein Structure
Peptide Bonds
Disulfide Bonds
Hydrogen Bonds
Hydrophobic Bonds
Electrostatic or ionic bonds
involves breaking the peptide bonds by treatment with aqueous acid, base, or certain enzymes
Protein hydrolysis
the process of altering the shape of a protein without breaking the amide bonds that form the primary structure: heat, acid, base, or agitation
Denaturation
Physical agents
Heat
Surface Tension
UV light
High Pressure
Chemical agents
Organic Solvent
1. Acids and Alkalines
2. Urea and guanidine
Detergents
Decreased solubility at the protein’s isoelectric point
Chemical Alterations brought about by denaturation
As a result of the unfolding process in denaturation, many chemical groups which were rather inactive awing be shielding of the native state become exposed and more readily detectable
Chemical Alterations brought about by denaturation
Increases in the viscosity of the solution, so the rate of diffusion of the protein molecules decrease
Physical Alterations brought about by denaturation
Increase levorotation
Physical Alterations brought about by denaturation
Denatured proteins cannot be crystallized since the formation of a crystal depends upon a high degree of organization of the molecules
Physical Alterations brought about by denaturation
Increased digestibility by proteolytic enzyme
Biological Alterations brought about by denaturation
Enzymatic or hormonal activity is usually destroyed
Biological Alterations brought about by denaturation
The antigenic or antibody functions of proteins are frequently altered as well
Biological Alterations brought about by denaturation
composed of long linear polypeptide chains that are bundled together to form rods or sheets. Insoluble and serve structural roles giving strength and protection to tissues
Fibrous proteins
are coiled into compact shapes with hydrophilic outer surfaces that make them water soluble. Enzymes and transport proteins are globular to make them soluble in blood and other aqueous environments
Globular proteins
These are proteins found in hair, hooves, nails, skin, and wool
having large numbers of alanine and leucine residues
α-Keratins
Insoluble in water since the polar amino acids extend outward of the alpha helix
α-Keratins
Two α-Keratins coil around each other, forming a structure called a
supercoil or superhelix
Most abundant protein in vertebrates, found in the connective tissues such as bones, cartilage, tendons, teeth and blood vessels
collagen
Glycine and proline account large fraction of its amino acid residues
collagen
forms an elongated left-handed helix
collagen
three of theses helices wind wound each other to form right handed
superhelix or triple helix
are proteins that serve as biological catalysts for reactions in all living organisms
enzymes
need for action to occur
catalyst
They increase the rate of a reaction (10^6 to 10^12 times faster), but are unchanged themselves.
enzymes
very specific; each of these catalyzes a certain reaction or type of reaction only
enzymes
The names of most enzymes end with the suffix
ase
a metal ion or an organic molecule needed for an enzyme-catalyzed reaction to occur
cofactor
It is a non-protein chemical that is bound to an enzyme and is required for catalysis
cofactor
2 types of cofactor
Coenzyme
Prosthetic Groups
enzymes involved in the transfer of electrons; they catalyze reactions involving removal of electrons from an electron donor and transfer them to an appropriate electron. Usually these reactions lead to the formation of ATP
Oxidoreductase
involved in transferring functional groups between donors and acceptors. Transfer of chemical groups other than hydrogen from one substrate to another
transferase
cause hydrolysis or splitting of a bond by the addition of
water
hydrolase
Catalyze the removal of groups from substrates without hydrolysis. The product contains double bond
Lyases
Catalyzes the interconversion of optical geometric or positional isomers
Isomerases
Involved in the synthetic reactions when two molecules are joined at the expense of an ATP “high energy phosphate bond”. Catalyze the joining of two substrate molecules, coupled with breaking of the pyrophosphate bonding ATP or similar compounds
Ligases
enzymes reacting
b. substrate
can bind to enzyme to form an enzyme substrate complex
substrate
made of long chain of amino acid and the chain are folded to form active site
enzymes
Extreme pH level may denature enzyme or influence its ionic state resulting in structural change
pH
the faster the reaction, because more enzyme is present to bind with the substrate
the higher the enzyme concentration
With the amount of enzyme exceeding the amount of substrate, the reaction rate steadily increases as more substrate is added.
Substrate Concentration
The ___ an enzyme is incubated with its substrate, the greater the amount of product that will be formed
longer
the reaction rate depends only on the enzyme concentration
Zero- order reaction
the reaction rate is directly proportional to substrate concentration
First – order reaction
is a molecule that causes an enzyme to lose activity
inhibitor
binds to an enzyme but then enzyme activity is restored when the inhibitor is released
Reversible inhibitor
has a shape and structure similar to substrate so it competes with the substrate for binding to active site
Competitive inhibitor
binds to the enzyme but does not bind at the active site
Non-Competitive inhibitors
Covalently binds ton an enzyme, permanently destroying its activity
Irreversible inhibitors
inactive type that dissolve the clot
plasiminogen
