Amino Acids, Proteins and Porphyrins
The primary role of chaperones is to help in:
a. Are the protein that prevent faulty folding and unproductive interactions of other proteins
b. play a role in the assembly or proper folding of other proteins.
c. ie. prevent wrong folding and allows folding, only in the correct direction.
d. They help in the assembly of the tertiary and quantimetry structure of proteins.
e. They are not part of the mature protein, and they have ATPase activity.
Some properties of chaperone proteins
a. Present in a wide range of species from bacteria to humans.
b. Many are so called heat shock protein (Hsp)
c. Some are inducible by conditions that cause unfolding of newly synthesized protein (eg. ↑temp., and
d. various chemicals)
e. They bind to predominantly hydrophobic regions of unfolded and aggregated proteins.
f. They act in part as a quality control or, editing mechanism. For detecting mis folded or other wise defective proteins.
g. Most chaperons show associated ATPase activity, with ATP or ADP being involved in the protein-
h. chaperone interaction
i. Found in various cellular components such as, cytosol, mitochondria and the lumen of the endoplasmic reticulum.
Some chaperones and enzymes involved in folding that are located in the rough
a. BIP (Ig heavy chain binding protein
b. GRP —94 (glucose — regulatory protein)
c. Calnexin (Ca++ binding protein)
d. Cal reticulum (Ca++ binding protein)
e. PDI (Protein disulfide isomerase)
a. PPI (Peptidylprolylcis-trans-isomerase)
Denaturation of the protein
a. — non specific alterations in the secondary, tertiary and quaternary structures of proteins causes
loss of biological activity, is called denaturation (Note →primary structure is not altered)
b. Causes → Brief heating, urea; Salicylate, X-ray, UV rays, high pressure, vigorous shaking, Acid, alkali, heavy metal salts, ethanol, guanidine, detergents etc.
c. Tertiary structure of protein → is only one such conformation which is biologically active → high
temperature causes denaturation of protein (= loss of tertiary structure) →destroys enzyme and hormonal activity and biologically becomes inactive.
Protein synthesis — takes place in ribosomes.