Monomeric cyt c has been reported to bind to the mitochondrial membrane by electrostatic and hydrophobic interactions with anionic phospholipids. We have previously shown that domain-swapped oligomeric cyt c retains the secondary structure of the monomer, and its surface possesses a larger area and more charges compared to the monomer. However, the effect of oligomerization of cyt c on cells has yet to be revealed. Herein, we investigated the interaction of oligomeric cyt c with anionic phospholipid-containing vesicles and the outer membrane of HeLa cells. Oligomeric cyt c interacted more strongly than monomeric cyt c with anionic phospholipid-containing vesicles and the outer membrane of HeLa cells. Oligomeric cyt c induced lateral phase separation of lipids in LUVs and GUVs, thereby leading to membrane disruption, whereas monomeric cyt c did not. Morphological changes in HeLa cells resulted from interaction with oligomeric cyt c, but little from interaction with the monomer. These results show that domain-swapped oligomeric proteins might exhibit properties different to those of monomer in cell systems.

Double stranded DNA was cleaved oxidatively by incubation with oxygenated myoglobin, and Lys96Cys sperm whale myoglobin in its stable ferric form functioned as an artificial nuclease under air by formation of an oxygenated species, owing to electron transfer from the SH group of the introduced cysteine to the heme.

Most proteins need to fold for functioning. Previously, the folding studies mostly focus on the proteins with unique native structure. However, there are a large number of functionally important allosteric proteins which can have two functional structures, depending on the binding state of cofactors. For these proteins, co-factor binding, conformational changes and folding can be tightly coupled, but the coupling mechanism is still unclear. In this work, by using the atomic interaction based coarse grained (AICG) model with a multiple-basin Hamiltonian, we study the folding coupled with binding and allosteric motions in calmodulin domains. In this meeting, we will present the details of this work. 2P050FTIR 分光法を用いたユビキチンの温度-圧力変性状態の研究 The secondary structure of ubiquitin is known to be constant around various pH, however its thermodynamic stability and FTIR spectrum drastically change on the boundary at pH 4. This fact indicate that minor conformation and hydrogen bond pattern of ubiquitin change by pH, and these difference may affect to thermodynamic properties. We observed pressure and temperature denaturation of ubiquitin by FTIR spectroscopy at pD (alternate of pH in heavy water) 2 and pD 5. Ubiquitin at higher pD was more stable than at lower pD. Moreover, the pressure denaturation process at higher pD showed at least three-state transition, while the denaturation at lower pD showed two-state transition. 2P051 Ritsumeikan)In general, protein folds into a unique structure and the structure unfolds by perturbing temperature and pressure. In the present study, we focus on the β-haripin structure, which is the simplest β-structure. Previously, we have reported that Trpzip4 (W43W45W52W54) which is a triple mutant of GB1 segment peptide (W43Y45F52V54) refolded by pressure. In the present work, we have expanded the research project to the other kinds of mutants, W43W45F52W54 (WWFW) and W43W45Y52W54 (WWYW). We observed the temperature and pressure effect on these peptides using FT-IR and CD spectroscopy. We compare the results and discuss the substitutional effects on the structural stability of the β-hairpin structure. Pressure effect on the structure of proteins and peptides has recently been studied theoretically and experimentally. Some peptides are more stable in the folded state than in the random coil state at high pressure. We studied pressure effect on a peptide that is stable at high pressure by using molecular dynamics simulations. We performed simulated tempering molecular dynamics simulations for the system of an AK16 peptide in explicit water molecules. We found that the population of the secondary structure of the peptide increases with pressure and that the peptide shrinks under high pressure conditions. We also calculated the partial molar volume change, and the calculated results were consistent with experimental results. 2P053 アミノ酸の物性に注目した疾患感受性遺伝子変異の判別 Discrimination of disease-susceptibility mutations by physicalproperties of amino acid fragments around the mutation