pression and modifications that are specific to particular tissues, parts of the cell cycle, or diseases. Projects include the development of methods for rapid and sensitive protein structural analysis, microsequence analysis of proteins with emphasis on proteins specific to Alzheimer's disease, and molecular dynamics simulations of protein/protein complexes. LABORATORY Recent results of one structural analysis suggest that polypeptides from two edible PROFILE Japanese mushrooms—Grifola frondosa ("maitake") and Pleurotus sstreatus Analytical research ("hiratake")—may become extremely helpful for structural studies of proteins. "These a t Riken mushrooms contain proteolytic enzymes at The Institute of Physical and Chemical Research is involved in research ranging rather high concentrations," Takio says. from high- energy physics to biomedical 'The most prominent one is a metalloendoapplications. Located near Tokyo, Japan, peptidase that specifically and efficiently hydrolyzes peptidyl-lysine bonds." The the institute is better known as Riken— mushroom enzymes are tolerant of the derived from Rikagaku, ,apanese for physics and chemistry, and Kenkyusho, high temperatures and agents such as urea, detergent or guanidinium hydrochloJapanese for research institute. Analytiride used to denature proteins. Because cal chemistry plays an important role in many areas of Riken's research, but ana- most of the peptides produced by the endopeptidase cleavage lysine residue lytical research is primarily carried out within the Department of Research Fun- at the amino terminus the mass spectra damentals Technology's Division of Bio- tend to be simpler and, easier to interpret molecular Characterization, Division of The Division of Molecular CharacterizaMolecular Characterization and Divition performs structural analyses by NMR sion of Surface Characterization. spectroscopy, MS, and X-ray diffraction. It supports chemical synthesis, biological Riken's was established in 1917 as a science, and materials science research for private scientific foundation. Following institute labs and Riken project teams. One World War II, the institute was reorganized as the Scientific Research Institute recent study involved the biosynthesis of the diakylmaletic anhydride-containing (or Kaken) but was beset by financial antibiotics tautomycin and tautomycetin, difficulties. In 1958, the institute assumed its present name and structure as which have similar structures. The biosynthesis was studied by feeding 13C-labeled a nonprofit corporation with a combinaprecursors such as sodium [l,2-13C]acetion of governmental and industrial fitate, sodium [l,2-13C]glutamate, and [1,2nancial support. 13 C]glycine, to die organisms producing The Division of Biomolecular Charthe antifungal compounds. The labeling acterization, which was started in 1991, patterns are analyzed with NMR "The provides physicochemical characterizapulsed-field gradient [pulse sequence tions including MS and NMR, Koji known as] INADEQUATE is very useful Takio, Division Head, tells Analytical Chemistry. "We still rely on Edman neg- and gives beautiful spectra of the C-C coupling pattern " says Jun Uzawa head of the radation for unambiguous [protein] seDivision of Molecular Characterization quence analysis, but we are shifting our primary instruments to mass spectromeMasaya Iwaki heads the Division of Surtry for higher sensitivity," Takio says. face Characterization. "Developing heavy ion accelerators for general industries, we The division will soon collaborate launched our beam analysis center in with researchers at the Tsukuba Life 1981," Iwaki said. "We apply a tandem acScience Center, another branch of celerator to surface analysis, investigate Riken. The goal of these projects is to develop a protein database that includes surface analysis methods and technologies, chemical and physical characteristics, as and develop ion implantation technologies for surface modification." Iwaki adds, "The well as information about protein ex-
M. Iwaki and Y. Suzuki operate a 200-keV low-current ion implanter.
modified materials are metals; inorganic compounds, such as ceramics and glasses; polymers; and carbon materials such as diamond and diamondlike carbon thin films." In collaboration with the Teikyo University School of Medicine, the Division of Surface Characterization has studied surface modification of polytetrafluoroethylene and collagen-coated specimens to control cell adhesion and their application to biomedical materials. 'We made small artificial grafts," Iwaki says, "whose inner diameter is 2 or 3 mm." First, Ne ions are bombarded onto the inner walls of small tubes and collagen is coated on the surfaces. Then, He-ions are bombarded onto the collagen-coated specimens. Endothelial cells adhere and platelets do not adhere to the modified surfaces. The grafts retained their cell adhesion and antithrombogenic properties even after being implanted in dogs for 240 days Iwaki says Another biomedical application is a new surface modification of platinum coils by ion implantation and protein coating for use in intravascular treatment of brain aneurysms, said Iwaki. The Jikei University School of Medicine and the UCLA Medical Center collaborated with Riken in this study. In these experiments, ion implantation was accomplished with a 200-keV lowcurrent implanter. Hitachi built this implanter in 1968 to dope boron, phosphorus, and arsenic in silicon and to fabricate electronic silicon devices. In 1970, Riken obtained the implanter and used it to modify the surfaces of metals and ceramics. The oldest ion implanter in Japan, it uses 60 elements to modify material surfaces. Despite its age, this implanter will continue to synthesize new and functional surfaces in the future, Iwaki predicts. Sandra Katzman
Analytical Chemistry News & Features, February 1, 1999 8 9 A
