Ribbon drawing of ribonuclease A.  The 4 disulfide bonds highlighted in yellow.  Beta strands are arrows, pale blue on one side of the sheet and pale green on the other, and alpha-helices are pink spirals.  Hand-drawn by Jane Richardson, 1980.
<a href="//commons.wikimedia.org/wiki/User:Dcrjsr" title="User:Dcrjsr">Dcrjsr</a>
CC BY 3.0
<span class="int-own-work" lang="en">Own work</span>