protein Flashcards by Mikaela Mendoza

Peptides and proteins are formed when amino acids are joined together by

amide bonds

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has two amino acids joined together by one amide bond

dipeptide

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The amide bond is called a

peptide bond

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have many amino acids, while proteins is usually reserved for polymers of > 40 amino acids.

Polypeptides

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The amino acid with the free –NH3+ group is the N-terminal amino acid and is written on the?

left

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The amino acid with the free –COO− group is the C-terminal amino acid and is written on the?

right

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pentapeptides synthesized in the brain act as pain killers and sedatives by binding to pain receptors

Enkephalins

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Enkephalins has two types

Met- enkephalin and leu-enkephalin

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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

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are cyclic nonapeptide hormones secreted by the pituitary gland. They are identical in structure except for two amino acids

Oxytocin and Vasopressin

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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

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Simple Proteins

Albumin
Globulins
Glutelins
Prolamines
Scleroproteins of Albuminoids
Histones
Protamines

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regulate ADH

vasopressin

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enzymes in lactation

oxytocin

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Conjugated Proteins

Nucleoproteins
Glycoproteins and mucoproteins
Phosphoteins
Chromoproteins
Lipoproteins
Metalloproteins

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for clot formation

fibrin

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part of clotting

prothrombin

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produce by plasma cells

antibodies

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transport nutrition

albumin

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regulates cholesterol

lipoproteins

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Proteins
Metaproteins
Coagulate Proteins

Primary Derived Proteins

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Proteases
Peptones
Peptines

Secondarily derived Proteins

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The ____ of a protein is the sequence of amino acids joined together by peptide bonds

primary structure

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is the 3D arrangement of localized regions of a
protein.

secondary structure

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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

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

protein Flashcards

(87 cards)