Jmol Hints:

1. Hit the zoom button to get a closer view
2. Hit the "His" or "Lys" buttons to highlight the atoms you are to measure the distance between.
3. To measure a distance, try: menu → Measurement → Click for distance measurement. Then click on two atoms and the distance between them will appear on the screen.

CPK Color Scheme:
blue - nitrogen  |  red - oxygen  |  gray - carbon  |  yellow - sulfur  |  hydrogen - white | phosphorus - orange