The native helical structure of protein is lost. The primary structure of a protein with peptide linkages remains intact; that is, peptide bonds are not hydrolysed. Protein loses its biological activity. Denaturated protein becomes insoluble in the solvent in which it was originally soluble. The viscosity of denaturated protein is increased. Denaturation is associated with…
Physical agents: Heat, violent shaking, X-rays, UV radiation, and high pressure (5,000–10,000 atm). Chemical agents: Acids, alkalis, organic solvents (ether and alcohol), aromatic anions (salicylates), salts of heavy metals (Pb and Hg), urea, and salicylates.
Physical agents: Heat, violent shaking, X-rays, UV radiation, and high pressure (5,000–10,000 atm). Chemical agents: Acids, alkalis, organic solvents (ether and alcohol), aromatic anions (salicylates), salts of heavy metals (Pb and Hg), urea, and salicylates.
‘The phenomenon of disorganisation of native protein structure is known as denaturation.’ Denaturation results in the loss of secondary, tertiary, and quaternary structures of proteins. This involves a change in physical, chemical, and biological properties of protein molecules.
Several insects and spiders produce silk substance that contains a fibrous protein, fibroin. In fibroin, which is considered to be a β-keratin, the polypeptide chains are arranged in anti-parallel β-pleated sheet confirmations because the pleated sheets are loosely bonded to each other (van der Waals force) as shown in Figure 3.18. They slide over each other…
Collagen is the most abundant protein in the vertebrates. It is present in skin, bones, blood vessels, and corneas. Collagen is composed of three left-handed polypeptide helices as shown in Figure 3.17 are twisted around each other to form right-handed super helix. The amino acid composition of collagen is different. Glycine constitutes one-third of amino acid residues.…
In fibrous proteins, bundles of helical polypeptide are commonly twisted together into larger bundles. The structural unit of the α-keratins—a class of proteins found in the hair, wool, skin, horns, and finger nails is an α-helical polypeptide. Each peptide has three domains: an amino terminal head domain, a central rod-like α-helical domain, and a carboxyl…
Fibrous proteins contain secondary structures such as α-helices or β-pleated sheets. As a result of the rod-like or sheet-like shapes, fibrous proteins have structural than dynamic roles.
Protein contains four subunits designated to α and β. Each subunit contains a haem group that binds reversibly with O2. The nine highly conserved amino acid residues in haemoglobin are given in Table 3.1. Table 3.1 Highly Conserved Amino Acid Residues in Haemoglobin Position Amino acid Role F8 Histidine Proximal haem-linked histidine E7 Histidine Distal haem-linked…
A fourth degree of complexity in protein structure has been recognised, which is known as quaternary structure. High molecular weight proteins are composed of several polypeptide chains. Each polypeptide components is called subunit. Subunits in a protein complex may be identical or quite different. The identical peptides in a polypeptide are referred to as oligomers.…