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EB-2000-10-183-MSFC

Educational Brief
A NASA Recipe For Protein Crystallography

Glucose Isomerase Crystals

Lysozyme Crystals

Excelsin Crystals

P

rotein crystals can be very difficult to grow. Even protein crystallographers are often unable to produce crystals ofthe high quality that is required to determine the molecular structure of many proteins. As part of NASA’s educational outreach activities, we have prepared a simple ‘recipe’ for growing protein crystals from Brazil nuts. Please let us know how your attempts at growing these protein crystals turn out. You may contact us at: microgravitynews@msfc.nasa.gov

For more up-to-date information aboutNASA’s macromolecular crystallography program, see: http://crystal.nasa.gov
Note: all bold face words are referenced in the glossary in the back of this document.

Introduction

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any hours of scientific study and investigation are invested in growing protein crystals – crystals that, when nearly perfect in form, are very highly prized. The information they reveal about a protein’s molecularstructure makes them very sought after and important to science. Proteins, macromolecules involved in everyday functions of the body such as transporting oxygen and chemicals in blood, forming major components of muscle and skin, and fighting disease, come in over 100,000 varieties. Active sites on molecules of proteins, when inappropriately triggered or absent, can cause disease or an unwantedfunction. Scientists seek to locate those active sites so drug designers can understand their function and then, in some cases, work to block them or render them inactive. For example, the anti-inflammatory drug ibuprofen works on a specific protein, which is involved early in the signaling process that tells your body that inflammation should occur. Blocking the active site on this protein preventsor reduces the inflammation.

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nfortunately, protein molecules

are so small that humans can’t see them individually, let alone find a specific site on a molecule or determine its molecular structure. If one cell in the human body were the size of a football stadium, one protein molecule would be approximately the size of a can of soda, and one of the atoms making up that proteinmolecule would be about the size of the fine print on the can.

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protein crystal is a three-dimensional array of molecules in which every molecule or specific group of molecules has the same orientation and relationship to its neighbors, as long as the chemical environment of the solution surrounding the crystal remains the same. When a protein crystal forms, protein molecules or groups ofmolecules align to produce a repeating three-dimensional pattern

Comparative sizes of proteins and the atoms making up proteins
molecule, by itself, would produce a signal so weak it would be undetectable. But if all the molecules in the crystal produced the same signal at exactly the same time, then that signal would be strong enough to be recorded and decoded. The more closely oriented oraligned the molecules making up the protein crystal are, the better the signal, and the more accurate the molecular information.

or array. The effect of bringing these molecules together in this arrangement is called amplification. Amplification can be thought of in this way: imagine a football stadium full of people. If only one person stands up and yells, the sound produced is not easily heard.But if everybody in the stadium stands up, faces the same direction and yells at the same time, that sound can be heard from a great distance. A very similar thing happens during the analysis of a protein crystal. One protein

EB-2000-10-183-MSFC

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A NASA Recipe For Protein Crystallography

History

T

he first known published observation of the

crystallization of a protein was...