PRE FI LEC 2: PROTEINS AND PROTEIN METABOLISM Flashcards
PROTEIN CLASSIFICATION BASED ON SHAPE
- are protein molecules with peptide chains that are folded into SPHERICAL or GLOBULAR shapes
- water solubles (because the hydrophobic amino acids residues of this protein are hidden in the protein core and what is shown outside is the hydrophilic amino are residue
- function as enzyme and intra cellular signalling molecules
Ex: MYOGLOBIN & HEMOGLOBIN
GLOBULAR
- is an oxygen storage molecules in muscle
- monomers are single peptide chain with heme unit so that is why it is capable of holding and transporting of oxygen
- binds one oxygen molecule
- 1 heme unit = 1 molecule of oxygen binding
- higher affinity of oxygen compared to hemoglobin
- serve as reserve oxygen source for working muscles
MYOGLOBIN
- is oxygen carrier molecule in the blood- transport oxygen from the lungs to various tissue of our body
- it has a unique structure because it is tentramer (4 polypeptide chains) each sub unit is a heme group
- 1 hemoglobin = 4 heme unit = 4 oxygen
- can transport 4 O2 at a time
- iron in heme interacts with oxygen
HEMOGLOBIN
PROTEIN CLASSIFICATION BASED ON SHAPE
- protein molecules with elongated shape
- insoluble in water (because the hydrophobic amino acid residue are exposed)
- single type of secondary structure of proteins
- simple and regular linear structures
- they tend to aggregate together to form macromolecules structure (aggregation contributes to rigid structure)
Ex: a-KERATIN & COLLAGEN
FIBROUS
FIBROUS
- provides protective coating for organs
- constituent of our nails and hair
- mainly made of hydrophobic amino acids residues that are hydrophobic that is why it is insoluble
- it’s hardness depends upon the SS bonds (disulfide bonds/bridges)
a - KERATIN
FIBROUS
- is the most abundant proteins in the body (30% of body protein)
- major structural material in our tendons, ligaments, blood vessels and our skin
- the more intake of collagen, the more glowing your skin appears to be
- organic component of bones and teeth
- rich in proline, it’s constitute up to 20%
Proline: important the structure
COLLAGEN
PROTEIN CLASSIFICATION BASED ON SHAPE
- this membrane proteins associated with cell membranes
- insoluble of water ( predominantly composed of hydrophobic amino acid on the surface)
- water insolubility of the memebrane helps in the transport of molecules in the membrane
Ex: Membrane proteins
MEMBRANOUS
WHAT ARE THE PROTEINS CLASSIFICATION BASED ON FUNCTION
- CATALYTIC
- DEFENSE
- TRANSPORT
- MESSENGER
- CONTRACTILE
- STRUCTURAL
- TRANSMEMBRANE
- STORAGE
- REGULATORY
- NUTRIENT
PROTEINS CLASSIFICATION BASED ON FUNCTION
- responsible for catalyzing reactions
- hastens chemical reactions
ex: ENZYMES
CATALYTIC
PROTEINS CLASSIFICATION BASED ON FUNCTION
- involves our immune systems
ex: IMMUNOGLOBULINS (or ANTIBODIES) & COMPLEMENT SYSTEM
- together they help fight foreign bodies or antigens
DEFENSE
PROTEINS CLASSIFICATION BASED ON FUNCTION
- binds small molecules such as oxygen
- transport them to other location of the body and release them based on the body demands
ex: MYOGLOBIN, HEMOGLOBIN, TRANSFERRIN
- helps transport of oxygen molecules in certain organs that needs oxygen
TRANSPORT
PROTEINS CLASSIFICATION BASED ON FUNCTION
- transmit signals to coordinate biochemical processes between different cells, tissues, and organs
ex: INSULIN & GLUCAGON - helps in regulation of carbohydrates metabolism
GROWTH HORMONES - regulation of body’s growth
MESSENGER
PROTEINS CLASSIFICATION BASED ON FUNCTION
- necessary for all forms of movement
- muscle contains the filament like contractile proteins such as ACTIN and MYOSIN
- in human reproduction it depends on the movement of the sperm
CONTRACTILE
PROTEINS CLASSIFICATION BASED ON FUNCTION
- confers stiffness and rigidity
ex: COLLAGEN & KERATIN (gives mechanical strength as well as protective covering to our hair nails, etc.)
STRUCTURAL
PROTEINS CLASSIFICATION BASED ON FUNCTION
- spans cell membrane and helps the movement of small molecules and ions
ex: CHANNEL PROTEINS and MEMBRANE- BOUND PROTEINS
- this proteins ahs channels which help molecules to enter and exit the cell, but the transport and passage of substances is very SELECTIVE
- ion-selective (they allow passage of certain type of molecule or ions based on their reactions that they facilitated
TRANSMEMBRANE
PROTEINS CLASSIFICATION BASED ON FUNCTION
- bind and store molecules
ex: FERRITIN - iron storage protein, saves iron for use of the biosynthesis of new hemoglobin molecules
MYOGLOBIN - oxygen storage protein
HEMOGLOBIN - oxygen binder and storage molecule
STORAGE
PROTEINS CLASSIFICATION BASED ON FUNCTION
- acts as site for receptor molecules
-these molecules often that binds to enzymes
- controls enzymatic activity (turn off/on)
- helps in the catalytic function of enzyme
REGULATORY
PROTEINS CLASSIFICATION BASED ON FUNCTION
- important in early stages of life (from embryo to infant)
ex: CASEIN - protein found in milk
OVALBUMIN - found in egg white
- milk contains certain immunoglobulin that when transferred to infants will contribute to his immunity
NUTRIENT
- reverse peptide bond formation
- results in the generation of a carboxylic acid and an amine group
- breaking covalent bonds
- addition of water molecules (responsible for cleaving the bond between the molecules)
- does not affect the biological activity of the protein
summary: breaking down of proteins into smaller peptides or amino acid by addition of water molecule
HYDROLYSIS
- occurs when exposed to extreme temperature, pH changes or certain molecules
- involves physical/chemical change that alters the structure of the protein, often result to the loss of biological activity
- unfolding of proteins
- partial or complete disorganization of protein’s tertiary structure
- coagulation: precipitation (denaturation of proteins)
- cooking: kills microorganisms by denaturation of proteins
- cooking food denatures the protein but does not change protein nutritional value
DENATURATION
contributes to the hydrolysis of proteins
ENZYMATIC REACTIONS & CHEMICAL REACTIONS
HYDROLYSIS OR DENATURATION
DEFINITION: is the process of proteins LOSING THEIR SHAPE
PROTEIN DENATURATION
HYDROLYSIS OR DENATURATION
DEFINITION: is the process of BREAKING PROTEINS into their building blocks of AMINO ACIDS
PROTEIN HYDROLYSIS
HYDROLYSIS OR DENATURATION
WHAT HAPPENS: proteins lose its 3 dimensional structure and shape
PROTEIN DENATURATION
HYDROLYSIS OR DENATURATION
WHAT HAPPENS: proteins convert into amino acids
PROTEIN HYDROLYSIS
HYDROLYSIS OR DENATURATION
FACTORS AFFECTING: high temp., pH changes, denaturing agents, alkaline and acid solutions, etc.
PROTEIN DENATURATION
HYDROLYSIS OR DENATURATION
FACTORS AFFECTING: enzymes and chemicals
PROTEIN HYDROLYSIS
HYDROLYSIS OR DENATURATION
RESULT: loss of biological activity
PROTEIN DENATURATION
HYDROLYSIS OR DENATURATION
RESULT: production of free amino acids peptides
PROTEIN HYDROLYSIS
carbohydrate chain is the _______in a GLYCOPROTEIN molecule
GLYCO
EXAMPLE OF GLYCOPROTEIN
COLLAGEN & IMMUNOGLOBULINS
- is a conjugate or complex protein with carbohydrates link to them
- any plasma membrane such as blood group markers, ABO Blood system, protein responsible for our blood type
GLYCOPROTEIN
- most abundant protein in the body
- it has triple helix structure
- it is rich in 4 hydroxyproline and 5 hydroxylysine
COLLAGEN
5 classes of IMMUNOGLOBULIN
IgG
IgA
IgM
IgE
IgD
- a glycoproteins that produces a protective response to invasion of microorganisms or foreign antigens
- binds with antigens via variable region (magkakaroon ng hydrophobic interactions or hydrogen bonding between the two)
IMMUNOGLOBULIN
GLYCOPROTEINS
FUNCTION: STRUCTURAL MOLECULE
COLLAGEN
GLYCOPROTEINS
FUNCTION: LUBRICANT AND PROTECTIVE AGENT
MUCINS
GLYCOPROTEINS
FUNCTION: TRANSPORT MOLECULE
TRANSFERRIN, CERULOPLASMIN
GLYCOPROTEINS
FUNCTION: IMMUNOLOGIC MOLECULE
IMMUNOGLOBULINS, HISTOCOMPATIBILITY ANTIGENS
GLYCOPROTEINS
FUNCTION: ENZYME
VARIOUS, e.g. ALKALINE PHOSPHATASE
GLYCOPROTEINS
FUNCTION: CELL ATTACHMENT-RECOGNITION SITE
PROTEINS INVOLVED IN CELL TO CELL COMMUNICATION (MESSENGER PROTEIN/GLYCOPROTEINS)
GLYCOPROTEINS
FUNCTION: INTERACT WITH SPECIFIC CARBOHYDRATES
LECTINS, SELECTINS (cell adhesion lectins), ANTIBODIES
- conjugated proteins that contain lipids as its prosthetic group
-major function is to help suspend lipids and transport them to the bloodstream
LIPOPROTEINS
4 MAJOR CLASSES OF PLASMA LIPOPROTEINS
- CHYLOMICRON
- VLDL (VERY LOW-DENSITY LIPOPROTEIN)
- IDL (INTERMEDIATE-DENSITY LIPOPROTEIN)
- LDL (LOW-DENSITY LIPOPROTEIN)
- HDL (HIGH-DENSITY LIPOPROTEIN
- transient lipoprotein
IDL
contains more protein than lipid content
HDL
- provide structural stability to the lipoprotein
- may function as ligands in lipoprotein receptor interactions
- can be cofactors in enzymatic processes in which it helps our body to regulate lipoprotein
APOLIPOPROTEINS
contains APOLIPOPROTEINS A, B-48, C, E
CHYLOMICRON
contains APOLIPOPROTEINS B-100, C, E
VLDL
contains APOLIPOPROTEINS B-100, E
IDL
contains APOLIPOPROTEINS B-100
LDL
contains APOLIPOPROTEINS A & C
HDL
contains mostly of TRIACYLGLYCEROL
VLDL & IDL
- bad cholesterol
- 50 % cholesterol and cholesteryl ethers which contribute to the plaque formation when deposited to our arteries which could lead to atherosclerosis
LDL
- good cholesterol
- most of its total volume is protein (40%)
HDL
secreted from small intestines
CHYLOMICRON
secreted from liver
VLDL, IDL, LDL
secreted from liver and small intestines
HDL
LIPOPROTEIN METABOLISM 2 PATHWAYS
EXOGENOUS PATHWAY
ENDOGENOUS PATHWAY
- triglycerides involves in this pathway is coming from the OUTSIDE ENVIRONMENT
- involves the food intake of an individual
EXOGENOUS PATHWAY
- after food intake ( especially if greasy or fatty; in small intestines, CHYLOMICRON is secreted (rich in triglycerides that is from the food intake of the person
- the dietary lipids that is absorbed in the small intestine
are incorporated into the chylomicron (w/APO B-48) which will now reach the systemic circulation - in systemic circulation, CHYLOMICRONS will encounter ADIPOSE TISSUE, the enzyme lipoprotein lipase (LPL) will break down triglycerides into FREE FATTY ACIDS and GLYCEROL which will now be deposited into the adipose tissue and will be the stored energy of our body
- Chylomicrons become smaller in size since triglyceride content is removed, which is now known as CHYLOMICRON REMNANTS (APO E) will be taken up by liver in which the process is called RECEPTOR MEDIATED ENDOCYTOSIS
- CHYLOMICRON REMNANTS binds to APO E receptor by liver for it to be endocytose or be able to enter inside the liver cells or hepatocytes
- this chylomicron remnants are used for the production of free fatty acids and cholesterol in the liver
EXOGENOUS PATHWAY
major apolipoprotein that is attach or embedded to CHYLOMICRON molecule
APO B-48
enzyme found in the adipose tissue
LIPOPROTEIN LIPASE
major apolipoprotein of CHYLOMICRON REMNANTS is…
APO E
- inside the liver processes
- starting products: free fatty acids and cholesterol ( formed in the exogenous pathway)
- entering the endogenous pathway, it will begin in the liver where the free fatty acids and cholesterol that is produced by the liver will be carried by VLDL out of the hepatic cells into the circulation
- in the circulation, VLDL will encounter the adipose tissue
- LPL enzyme in the adipose tissue, which will break down the triglycerides into free fatty acids and cholesterol
- VLDL might become IDL OR EMPTY HDL
- IDL will go back to the liver since it just a transient lipoprotein, it is needed to be conjugated again
- in the liver IDL will be converted into LDL via the help of Hepatic lipase (HPL)
- LDL, on the transport of cholesterol from the liver to the extrahepatic tissues such as peripheral tissues
ex: adrenocortex where LDL receptors are present - after cholesterol has been delivered to various organs, LDL will go back again to the liver to carry again molecules of cholesterol
ENDOGENOUS PATHWAY
conversion of IDL to LDL is aided by the enzyme…
HEPATIC LIPASE (HPL)
- synthesized and secreted from both the liver and intestines
EMPTY HDL
EMPTY HDL from the intestines contains ________ and _______________
APOLIPOPROTEIN A (APO A) & FREE CHOLESTEROL
EMPTY HDL needs to encounter _______ in the circulation
- ___________ is a plasma enzyme that helps in esterifying the cholesterol content of HDL
- HDL now holds esterified cholesterol if it encounters this enzyme
LCAT (LECITHIN CHOLESTEROL ACYL TRANSFERASE
-________________ will form the core of HDL
- initial discoid shape of HDL will be spherical shape which will serve its function BEST
- now it can take up excess cholesterol deposited in various organs
NON - POLAR CHOLESTEROL
- IS A TRANSPORTER OF DIETARY LIPIDS
CHYLOMICRONS
IS A TRANSPORTER OF ENDOGENOUS LIPIDS (mainly triglycerides)
VLDL
- TRANSPORTS CHOLESTEROL TO PERIPHERAL CELLS
LDL
- TRANSPORTS CHOLESTEROL FROM PERIPHERAL CELLS BACK TO THE LIVER
HDL
