Art in Science — Protein crystals
Believe it or not, science can be quite artistic. (See the end of the post for a description of the flower crystal image shown below.)
Here, I am going to draw an example from my research laboratory, where we look at particular proteins that are very important in the heart and skeletal muscle. But the proteins are way too small to actually look under a microscope. One way to find out how they look like is to use a nanotechnology called protein X-ray crystallography. The basic principle is that when a protein crystal is shot with an X-ray, it gives out a unique diffraction pattern, which is recorded as multiple, tiny dots (see the picture below). Crystallographers can, then, decipher these dots and calculate the exact whereabouts of the atoms making up that protein, giving us the structure of the protein.
Protein crystals are usually formed in a tiny, 2-μl drop. These drops are tiny specks, just a couple of millimeter (mm), so that you’d have to squint to look at them. Each protein crystal is typically much smaller than 1mm (or 0.04inches) in size, only visible under a microscope.
In many cases, the most challenging step in the process of protein X-ray crystallography is to make protein crystals. Crystals form when multiple copies of the same protein form a neatly arranged, repeating units. (Think of nicely packed bricks in a brick wall or kernels of a corn.) Unfortunate for crystallographers, proteins are much likely to stay free in solution or get gooey and form random aggregates; crystallization process is often trial-and-error, and we have to screen for particular cocktails of solutions that coax the proteins to neatly arrange and pack themselves into crystals. We typically screen almost 1,000 conditions for one protein and, if we are lucky, get just a couple of hits. But when we do get crystals, they may have quite interesting appearances!
Why is it important to know the exact shape of a protein? For one thing, if we know how the protein looks like, it is much easier to study it. Scientists can point out parts that seem to be critical in a certain function (like interacting with cell-surface receptors, etc.) and find out what happens when they are altered, or mutated. In this way, we can understand the exact role and action of the protein and figure out how certain diseases are developed. Knowing how diseases occur and what went wrong with the protein’s proper function, it will be easier to find or improve treatments. For example, knowing the structure of proteins that are important in the heart would enable us to understand how heart diseases occur and allow us to strategically develop effective treatments.
Furthermore, if the exact shape of the protein is known, it is easier to design drugs that work better. This is particularly useful for finding new or stronger drugs and for reducing side effects. A very specific example is the search for better chronic pain treatment by studying the structure of opioid receptors (proteins that can bind opioid drugs), so that drugs can be designed to provide better pain relief while causing no psychoactive and other unwanted side effects. Another example is research on antibiotic resistance. Scientists study the exact binding between bacterial proteins and antibiotics to understand how resistance occurs and to design drugs that can bind more effectively.
Lastly, back to the image of protein crystals at the very top of the post… They are crystals of a protein that is crucial in muscle contractions. The crystals spontaneously grew into a flower-like shape, and the image was artificially colored. (Now you know what the header image of this blog is!
For more artistic science, check out nano-scale emoticons made with DNA.
For more crystal images, check out Crystal Gallery (Hampton Research).
Thank you for reading the post, and see you next week 🙂