This, against the backdrop of growing public awareness of the limitation of oil and gas resources as natural sources of energy
By Uri Nitzan
Photo: Eyal Varshavsky: Prof. Nehushtai. managed to isolate the 11 genes involved in the activity of one of the two photosynthesis systems in the plant cell
In recent years, public awareness of the limitations of oil and gas as a source of energy has been increasing. These are natural resources whose quantity is limited, and they are dwindling. The plant, on the other hand, is able to create an energetic "is" from the unlimited sunlight. In the process of photosynthesis, the plant converts the photon (the smallest energy particle that makes up a light beam) into an "energy currency" contained in carbohydrates.
The technological attempts to use the sun's energy have been partially successful, and solar energy systems operate with a utilization of up to 15%. In photosynthesis, 100% of the photons are used, and the energy utilization channeled to create chemical substances is about 60%. In order to imitate the process of photosynthesis, basic biological research is needed that will reveal the The molecular components of the system and the connections between them. Prof. Rachel Nehushtai, from the Department of Plant Sciences at the Hebrew University, researches the protein complex "Photosystem1, one of the two systems of photosynthesis in the plant cell. This system is located in the membrane of the intracellular organelles (chloroplasts), where light is absorbed and converted into chemical energy.
The research work began back in the early 80s as part of a doctoral thesis under the direction of Professor Nathan Nelson at the Technion, and since then Prof. Nekhustai has been able to isolate the 11 genes that code for the proteins involved in the system's activity. In order to describe the way in which these proteins fold in space, and arrange themselves in relation to each other, additional research in the field of "crystallography" was needed. The study of proteins in solution has been accepted for many years, and the purpose of crystallography is to study the properties of the protein in its solid form, as a crystal. "The formation of the protein into a crystal allows us to describe the three-dimensional atomic structure of the protein," says Nehushtai, "and this is important in understanding the activity and organization of proteins." . In the first stage, the proteins are extracted from the fatty membrane in which they are interwoven. The separation is done using soap-like substances that dissolve the lipid molecules that make up the membrane.
After the extraction, hundreds of proteins remain in the system, and the desired protein complex is "fished" from the mixture. The "fishing" is done on the basis of the biological activity of the complex - the amount of light it absorbs, its weight and its electrical charge. Using specific antibodies it is possible to mark the proteins and track their isolation. At the end of the "fishing" the test tube contains a clean, homogeneous and active Photosystem 1 complex.
The crystallization itself involves the slow removal of the liquid in which the clean complex is dissolved, and is based on laboratory protocols that are still under development. The resulting crystal consists of many units of the desired complex, arranged next to each other in space. The cleaner and more orderly the crystal, the greater the ability to extract information from it.
The next step involves advanced computer systems, and it involves sending X-rays to the crystal and accurately measuring the angles of refraction of the rays. Based on the measurements, the computer is able to decipher the three-dimensional structure of the system, and determine the arrangement of its atoms in space.
Several photosynthetic systems from different bacteria and algae have already been formulated, and in the coming years, Prof. Nushtai hopes, with the help of her research students, to complete the deciphering of the structure of "Photosystem 1" from the alga Mastigocladus laminosus, in parallel with the cellular-biological research to decipher the organization of the components of the photosynthetic system in membranes, the research system of ""Photosystem 1 is an excellent model for working with cell membrane proteins in general (membrane proteins). Unlike the water-soluble intracellular proteins, the membrane proteins are embedded in the lipid membrane, and sometimes also cross it. While the molecular-atomic structure of thousands of soluble proteins has already been described in databases, only about ten membrane proteins have been formulated to date, despite their central role in the economy of life.
"Membrane proteins are of enormous importance, as they form a connecting unit between the cell and its environment. These proteins function as receptors on the cell membrane," says Nehushtai, "and they are responsible for many processes in the nerve transmission system, in the action of hormones, in the generation of energy and in other vital processes." Not surprisingly, more than 80% of the drugs on the market work against membrane proteins.
The development of a new drug against a membrane protein is based on the spatial compatibility between the drug molecule and the three-dimensional structure of the receptor. This adjustment is made possible on the basis of research methods similar to those used in the study of the "Photosystem 1".
The ever-increasing interest in the research model of "Photosystem 1 and in crystallography in general made possible the establishment of the DET Consortium (Diagnostics, Kits and Medicines). The Center for Crystallography and Protein Research at the Hebrew University was chosen as an infrastructural center for the consortium, which gathers around it academic researchers and pharmaceutical companies. Prof. Nushtahai was chosen to R. The Consortium.
"The goal of the center is to concentrate knowledge and resources," says Nehushtai, "and to build trust and cooperation between the biotechnological industry and the academic institutions in a way that ensures cooperation between basic research centers and the implementing industrial groups."
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