Discovery of Small-Molecule Compound Uncovering Protein Function - Identification of a new bioprobe by chemical array screening, a rapid protein screening system (Press Release)
- Release Date
- 16 Aug, 2010
- BL26B2 (RIKEN Structural Genomics II)
RIKEN
Key research findings
• First-ever discovery of a pirin inhibitor, triphenyl compound A (TPh A), by chemical array screening
• Observation of molecular binding between TPh A and pirin by X-ray crystallography
• Clarification of involvement of pirin in migration of melanoma cells using TPh A as a bioprobe
|
Scientists at RIKEN (Ryoji Noyori, President) discovered a small-molecule compound with a molecular weight of only about 400, namely, triphenyl compound A (TPh A)*1, by chemical array screening for the first time in the world. TPh A disrupts the function of pirin*2, a protein with as yet unknown functions, that is widely expressed in human tissues. The scientists also examined the function of pirin using TPh A, clarifying its involvement in the migration of melanoma*3 cells. These achievements were obtained by the group led by Hiroyuki Osada, the director, and Isao Miyazaki, a research scientist, of the Chemical Biology Department, RIKEN Advanced Science Institute (Kohei Tamao, Director). The clarification of the functions of proteins that play important roles in human life activities will lead to the development of drugs and health food materials, as well as provide clues to unveiling the mystery of life phenomena. A small-molecule compound that binds to a specific target protein and disrupts its function can be used to clarify the functions of the protein. Such small molecules that disrupt the functions of proteins are called bioprobes (probes for biological functions). Bioprobes are expected to not only play important roles in research on proteins but also serve as candidate materials of new drugs. The research group has thus far developed a chemical array screening technique as an effective method of exploring various protein bioprobes. In this method, approximately 2,000-30,000 small-molecule compounds are immobilized on glass slides, onto which target protein molecules are added to detect the small-molecule compounds that physically bind to the target protein. The developed chemical array screening technique is attracting much attention as an excellent next-generation system for exploring proteins because of its high screening capability and general versatility, by which various proteins can be tested. The research group discovered TPh A, a new inhibitor of pirin, the function of which remained unclear, by chemical array screening. Using TPh A as a bioprobe, the group also clarified for the first time in the world that pirin is involved in the migration of melanoma cells. In addition, the group succeeded in forming a cocrystal in which TPh A is bound to pirin and in clarifying the binding states of the two compounds at the molecular level by X-ray crystallography using RIKEN Structural Genomics II Beamline (BL26B2) at SPring-8. The achievements of this research will enable molecular-level research on pirin using TPh A as a bioprobe. The chemical array screening technique is expected to be widely used as a new method of identifying bioprobes because it is applicable to testing all types of protein. The results of this research were published online in the British scientific journal Nature Chemical Biology on 15 August 2010 prior to the printed version. Publication: |
<Figure>
Fig. 1 Ninety-six-well plates and chemical array
The size of 48 96-well plates (left) is compared with that of a chemical array (right). When one chemical array is used, 4,608 types of small-molecule compound immobilized on a glass slide can be simultaneously screened. In contrast, 48 96-well plates are required to examine the same number of compounds (a stack of 48 plates is nearly 1 m high, as shown in the left figure).
Fig. 2 Method of fabricating chemical array and binding of small-molecule compounds with target protein
The aryldiazirine moiety is prepared on glass slides, onto which various small-molecule compounds are spotted. Subsequently, carbene species is produced from the aryldiazirine moiety upon ultraviolet light irradiation. Carbene species is highly reactive and immobilizes various small-molecule compounds onto the glass slides. Target protein molecules are added onto the thus-obtained chemical array to detect small-molecule compounds that bind to the target protein.
Fig. 3 Pirin-TPh A cocrystal structure
The green ribbon represents the N-terminus of the amino group of pirin, and the light-blue ribbon represents the C-terminus of the carboxyl group. The orange ball at the center represents an iron (II) ion. The molecules shown in purple in the vicinity of the orange ball form the structure of TPh A.
<Glossary>
*1 Triphenyl compound A (TPh A)
TPh A is a small-molecule compound discovered as a pirin inhibitor in this research. Here, TPh A is named after its structure with three phenyl groups.
*2 Pirin
Pirin is composed of 290 amino acids and widely expressed in human tissues. Pirin belongs to the cupin superfamily, which is a group of proteins with the largest variety of functions among all protein families reported thus far and includes various types of protein, such as enzymatic and nonenzymatic proteins. The functions of pirin in human tissues remain unclear.
*3 Melanoma
Melanoma is a malignant tumor of melanocytes, which are melanin-producing cells. A melanocytic nevus (mole) is a benign tumor of melanocytes. Melanoma is highly metastatic.
For more information, please contact: |
- Current article
- Discovery of Small-Molecule Compound Uncovering Protein Function - Identification of a new bioprobe by chemical array screening, a rapid protein screening system (Press Release)