Q.Secondary structure of protein

Step 1. Secondary structure (section 14.3.4b) has two standard representations; either is an acceptable diagram of 'secondary structure of protein'.

Step 2 (alpha-helix option). Draw the polypeptide backbone as a right-handed coiled spiral (Fig. 14.19); mark a bracket spanning 3.6 residues as one complete turn; draw R groups projecting outward from the coil at each residue; draw a dashed hydrogen bond running roughly parallel to the helix axis, connecting the C=O of one residue to the N-H of the residue four positions further along the SAME chain.

Step 3 (beta-pleated-sheet option). Draw two or more extended, zig-zag polypeptide strands lying side by side (Fig. 14.20); draw the backbone C=O and N-H groups lying roughly in the plane of the sheet; draw dashed hydrogen bonds running ACROSS between adjacent strands (N-H of one strand to C=O of the next, and vice versa); draw R groups projecting alternately above and below the sheet's plane. …

Draw either standard secondary-structure diagram from section 14.3.4b: the alpha-helix (Fig. 14.19, within-chain i-to-i+4 hydrogen bonding) or the b …

• Drawing a fully-folded 3-D globular shape (that is TERTIARY structure, section 14.3.4c) instead of the specific repeating local pattern (alpha-helix or beta-sheet) that defines secondary structure. …