The Molecule that Makes Breathing Worthwhile - Hemoglobin is the iron-bearing protein that most animals use to carry oxygen from their lungs to their muscles, or wherever it’s needed for metabolism, i.e. life. It’s the most important part of red blood cells, and its iron is what makes them red.

This sculpture, etched in a heavy 3 1/4″ glass cube, shows hemoglobin’s beautiful structure: the four heme groups each with its iron atom, the two alpha and two beta subunits, and the translucent molecular surface over all.

As well as being handsome and useful, hemoglobin is a star of scientific history. With its close relative myoglobin, it was the first protein to have its 3D structure determined by X-ray crystallography. Max Perutz and John Kendrew at Cambridge University received the Nobel Prize in 1962 for doing it.

The points are tiny (.1mm) fractures created by a focused laser beam. The conical beam, with a focal length of about 3″, shines into the glass without damaging it except at the focal point. At that one point, concentrated energy heats the glass to the cracking point, causing a microfracture.

To draw more points, the laser is pulsed on and off. To make the beam move between points, it’s reflected from a mirror that is repositioned between pulses. The mirror is moved by computer-controlled motors, so many points can be drawn with great speed and accuracy. A typical design might use several hundred thousand points, or half a million isn’t unusual in a large block, each placed with .001″ accuracy.