진경식 교수

The pH-dependent structures of the ferritin shell (apoferritin, 24-mer) and the ferrihydrite core, under physiological conditions that permit enzymatic activity, were investigated by synchrotron small-angle X-ray scattering (SAXS). The solution structure of apoferritin was found to be nearly identical to the crystal structure. The shell thickness and hollow core volumes were estimated. The intact hollow spherical apoferritin was stable over a wide pH range, 3.40-10.0, and the ferrihydrite core w

SMC condensin complexes are central modulators of chromosome superstructure in all branches of life. Their SMC subunits form a long intramolecular coiled coil, which connects a constitutive "hinge" dimerization domain with an ATP-regulated "head" dimerization module. Here, we address the structural arrangement of the long coiled coils in SMC complexes. We unequivocally show that prokaryotic Smc-ScpAB, eukaryotic condensin, and possibly also cohesin form rod-like structures, with their coiled coi

The first in-situ two-dimensional grazing incidence small-angle X-ray scattering (2D GISAXS) study on the evolution of nanopores during the thin film formation of porous dielectrics from composite films is reported. A soluble poly(methylsilsesquioxane) (PMSSQ) precursor and a four-armed poly(ε-caprolactone) (PCL4) were chosen as the model matrix and porogen components within the composite film. The measured 2D GISAXS data were analyzed quantitatively using a GISAXS formula derived under the dist

In order to achieve a hydrogel capable of programmable volume change, poly( N -isopropylacrylamide)- graft -methylcellulose hydrogel (PNIPAm- g -MC) was prepared through the grafting of PNIPAm onto a MC backbone and simultaneous cross-linking of the chains. PNIPAm- g -MC exhibited large thermal hysteresis in its volume change, which results from the stable hydrophobic junctions between the MC strands formed during heating. By combining photothermal magnetite nanoparticles as a heat transducer wi

We have investigated for the first time the structure of i-motif DNA in solution at various pH conditions by using synchrotron small-angle X-ray scattering technique. To facilitate direct structural comparison between solution structures of i-motif DNA at various pH values, we created atomic coordinates of i-motif DNA from a fully folded to unfolded atomic model. Under mild acidic conditions, the conformations for i-motif DNA appeared to be similar to that of the partially unfolded i-motif atomi

There are two beamlines (BLs), 4C1 and 4C2, at the Pohang Accelerator Laboratory that are dedicated to small angle X-ray scattering (SAXS). The 4C1 BL was constructed in early 2000 and is open to public users, including both domestic and foreign researchers. In 2003, construction of the second SAXS BL, 4C2, was complete and commissioning and user support were started. The 4C2 BL uses the same bending magnet as its light source as the 4C1 BL. The 4C1 BL uses a synthetic double multilayer monochro

Katanin was the first microtubule (MT)-severing enzyme discovered, but how katanin executes MT severing remains poorly understood. Here, we report X-ray crystal structures of the apo and ATPγS-bound states of the catalytic AAA domain of human katanin p60 at 3.0 and 2.9 Å resolution, respectively. Comparison of the two structures reveals conformational changes induced by ATP binding and how such changes ensure hexamer stability. Moreover, we uncover structural details of pore loops (PLs) and show

Structural characteristics of various conformational states of porcine pepsin in solution under different pH conditions were investigated in terms of size and shape by small-angle X-ray scattering (SAXS). Low-resolution structural models of porcine pepsin were reconstructed from SAXS data, which were made inside the search volume of maximum dimension (Dmax), calculated from the pair distance distribution function p(r). The reconstructed structural models were obtained without imposing any restri

We present a simple and industrially accessible method of producing liquid crystalline lipid nanoparticles with various internal structures based on phytantriol, Pluronic F127, and vitamin E acetate. Bilayer vesicles were produced when an ethanolic solution dissolving the lipid components was mixed with deionized water. After the evaporation of ethanol from the aqueous mixture, vesicles were transformed into lipid-filled liquid crystalline nanoparticles with well-defined internal structures such

The structural effects of fullerene on i-motif DNA were investigated by characterizing the structures of fullerene-free and fullerene-bound i-motif DNA, in the presence of cDNA and in solutions of varying pH, using circular dichroism and synchrotron small-angle X-ray scattering. To facilitate a direct structural comparison between the i-motif and duplex structures in response to pH stimulus, we developed atomic scale structural models for the duplex and i-motif DNA structures, and for the C(60)/

Porcine pepsin is a gastric aspartic proteinase that reportedly plays a pivotal role in the digestive process of many vertebrates. We have investigated the three-dimensional (3D) structure and conformational transition of porcine pepsin in solution over a wide range of denaturant urea concentrations (0-10 M) using Raman spectroscopy and small-angle X-ray scattering. Furthermore, 3D GASBOR ab initio structural models, which provide an adequate conformational description of pepsin under varying de