The Blueprint for Better Drugs
To design an effective drug, you first need a perfect blueprint of your target. In the human body, that target is almost always a protein. Diseases often arise because a specific protein is malfunctioning. A drug works by binding to that protein—like
a key fitting into a lock—to alter its behaviour. If the key is a perfect fit, the drug is effective with minimal side effects. If it's a poor fit, it won't work well and might unlock other, unwanted processes. To understand the exact shape of this 'lock', scientists need to see the protein's three-dimensional structure in atomic detail. The best way to do this is through a process called X-ray crystallography. This involves growing a crystal of the protein and then shining a powerful X-ray beam on it. The way the beam scatters allows researchers to map the protein's intricate structure. The catch? Growing a perfect protein crystal on Earth is incredibly difficult.
Why Gravity Gets in the Way
On Earth, gravity creates two major problems for crystal growth: sedimentation and convection. As protein molecules in a solution begin to arrange themselves into an ordered, crystalline lattice, their own weight causes them to sink. Furthermore, tiny temperature and density variations in the solution create currents, a process known as convection. This constant churning jostles the delicate, growing crystal structure. The result is often a small, flawed, and structurally imperfect crystal. These imperfections create a blurry or incomplete picture when analysed, forcing drug designers to work with an imprecise blueprint. This can lead to years of trial and error, costing pharmaceutical companies immense time and money to develop a drug that fits its target protein just right.
The Zero-Gravity Advantage
In the microgravity environment of the International Space Station (ISS), these terrestrial problems disappear. With no significant gravitational pull, there is no sedimentation. The protein molecules float freely. Convection is also virtually eliminated, creating a perfectly still environment. In this serene setting, molecules in the solution can assemble into a crystal lattice slowly and methodically, without being disturbed. This allows them to grow larger, more uniform, and with a near-perfect internal structure. Research has shown that crystals grown in space are superior in up to 92% of cases, with improvements in size, uniformity, and resolution. This higher quality allows for much sharper diffraction data, providing scientists with the high-definition molecular maps they need for rational drug design.
From Space Station to Pharmacy
For over two decades, the ISS has served as a unique laboratory for this research, with protein crystal growth (PCG) being the single largest category of experiments conducted on board. Astronauts aboard the station manage experiments for academic institutions and major pharmaceutical firms like Merck, Eli Lilly, and Bristol Myers Squibb. These experiments have targeted a wide range of diseases. Research conducted by the Japan Aerospace Exploration Agency (JAXA) on the ISS has led to the discovery of potential drugs for Duchenne Muscular Dystrophy (DMD), breast cancer, and gum disease. Other studies have helped determine the structure of targets for anti-tuberculosis drugs. More recently, research on Merck’s cancer drug Keytruda has used microgravity to study its crystalline structure, which helped in the development of a new, injectable form of the treatment, offering a time-saving alternative to intravenous infusions for patients.
