PubMed Health⌕ Search

Biomedical subjects

J Y Suh

Publications and source records attributed to J Y Suh.

9 recordsLinked to original sources
PubMed2005

Developing technologies for rainwater utilization in urbanized area.

Rainwater utilization has potential to recover the hydrological cycle, to buffer extreme run-off situations in the watercourses, and to reduce the costs for water supply in urban areas. However, relatively few works have been done for developing technologies to improve the water quality during rainwater utilization in large cities where the contamination of rainwater is anticipated. Therefore, this study focused on developing technologies for rainwater utilization subsystems including catchment, storage, treatment, infiltration, and use for buildings in urban areas. The rainwater samples collected from roof and roof garden were compared with wet deposition to analyze and identify the major components that may cause problems in rainwater utilization. Based on these results, novel techniques utilizing TiO2, sunlight, and bauxsol to minimize the contamination level by particles, microorganisms, and nutrients were developed for rainwater subsystems and applied to explore their suitability.

Cities↗
PubMed2001

Backbone dynamics of receptor binding and antigenic regions of a Pseudomonas aeruginosa pilin monomer.

Pilin is the major structural protein that forms type IV pili of various pathogenic bacteria, including Pseudomonas aeruginosa. Pilin is involved in attachment of the bacterium to host cells during infection, in the initiation of immune response, and serves as a receptor for a variety of bacteriophage. We have used (15)N nuclear magnetic resonance relaxation measurements to probe the backbone dynamics of an N-terminally truncated monomeric pilin from P. aeruginosa strain K122-4. (15)N-T(1), -T(2), and [(1)H]-(15)N nuclear Overhauser enhancement measurements were carried out at three magnetic field strengths. The measurements were interpreted using the Lipari-Szabo model-free analysis, which reveals the amplitude of spatial restriction for backbone N-NH bond vectors with respect to nano- to picosecond time-scale motions. Regions of well-defined secondary structure exhibited consistently low-amplitude spatial fluctuations, while the terminal and loop regions showed larger amplitude motions in the subnano- to picosecond time-scale. Interestingly, the C-terminal disulfide loop region that contains the receptor binding domain was found to be relatively rigid on the pico- to nanosecond time-scale but exhibited motion in the micro- to millisecond time-scale. It is notable that this disulfide loop displays a conserved antigenic epitope and mediates binding to the asialo-GM(1) cell surface receptor. The present study suggests that a rigid backbone scaffold mediates attachment to the host cell receptor, and also maintains the conformation of the conserved antigenic epitope for antibody recognition. In addition, slower millisecond time-scale motions are likely to be crucial for conferring a range of specificity for these interactions. Characterization of pilin dynamics will aid in developing a detailed understanding of infection, and will facilitate the design of more efficient anti-adhesin synthetic vaccines and therapeutics against pathogenic bacteria containing type IV pili.

Anisotropy↗
PubMed1999

Matrix GLA protein is a developmental regulator of chondrocyte mineralization and, when constitutively expressed, blocks endochondral and intramembranous ossification in the limb.

Matrix GLA protein (MGP), a gamma-carboxyglutamic acid (GLA)-rich, vitamin K-dependent and apatite-binding protein, is a regulator of hypertrophic cartilage mineralization during development. However, MGP is produced by both hypertrophic and immature chondrocytes, suggesting that MGP's role in mineralization is cell stage-dependent, and that MGP may have other roles in immature cells. It is also unclear whether MGP regulates the quantity of mineral or mineral nature and quality as well. To address these issues, we determined the effects of manipulations of MGP synthesis and expression in (a) immature and hypertrophic chondrocyte cultures and (b) the chick limb bud in vivo. The two chondrocyte cultures displayed comparable levels of MGP gene expression. Yet, treatment with warfarin, a gamma-carboxylase inhibitor and vitamin K antagonist, triggered mineralization in hypertrophic but not immature cultures. Warfarin effects on mineralization were highly selective, were accompanied by no appreciable changes in MGP expression, alkaline phosphatase activity, or cell number, and were counteracted by vitamin K cotreatment. Scanning electron microscopy, x-ray microanalysis, and Fourier-transform infrared spectroscopy revealed that mineral forming in control and warfarin-treated hypertrophic cell cultures was similar and represented stoichiometric apatite. Virally driven MGP overexpression in cultured chondrocytes greatly decreased mineralization. Surprisingly, MGP overexpression in the developing limb not only inhibited cartilage mineralization, but also delayed chondrocyte maturation and blocked endochondral ossification and formation of a diaphyseal intramembranous bone collar. The results show that MGP is a powerful but developmentally regulated inhibitor of cartilage mineralization, controls mineral quantity but not type, and appears to have a previously unsuspected role in regulating chondrocyte maturation and ossification processes.

1-Carboxyglutamic Acid↗
PubMed1999

Structural and functional implications of a proline residue in the antimicrobial peptide gaegurin.

Although it is commonly known as a helix breaker, proline residues have been found in the alpha-helical regions of many peptides and proteins. The antimicrobial peptide gaegurin displays alpha-helical structure and has a central proline residue (P14). The structure and activity of gaegurin and its alanine derivative (P14A) were determined by various spectroscopic methods, restrained molecular dynamics, and biological assays. Both P14 and P14A exhibited cooperative helix formation in solution, but the helical stability of P14 was reduced substantially when compared to that of P14A. Chemical-shift analysis indicated that both of the peptides formed curved helices and that P14 showed diminished stability in the region around the central proline. However, hydrogen-exchange data revealed remarkable differences in the location of stable amide protons. P14 showed a stable region in the concave side of the curved helix, while P14A exhibited a stable region in the central turn of the helix. The model structure of P14 exhibited a pronounced kink, in contrast to the uniform helix of P14A. Both peptides showed comparable binding affinities for negatively charged lipids, while P14 had a considerably reduced affinity for a neutral lipid. With its destabilized alpha-helix, P14 exhibited greater antibacterial activity than did P14A. Hence, electrostatic interaction between helical peptides and lipid membranes is believed to be the dominant factor for antibacterial activity. Moreover, helical stability can modulate peptide binding to membranes that is driven by electrostatic interactions. The observation that P14 is a more potent antibacterial agent than P14A implies that the helical kink of P14 plays an important role in the disruption of bacterial membranes.

Amides↗
PubMed1999

Structural characteristics of tenecin 3, an insect antifungal protein.

Tenecin 3, an antifungal protein, previously isolated from the insect Tenebrio molitor, inhibits growth of the fungus Candida albicans. However, the antifungal mechanism and functions of tenecin 3 remain unknown. As an initial step to study the mechanism and functions, physical and structural properties of tenecin 3 were examined by circular dichroism (CD) analysis and 2D nuclear overhauser effect spectroscopy. These analyses suggest that tenecin 3 has a propensity of random structure with very loose turn-like elements. The CD results also indicate that this random structural propensity is not significantly affected by temperature, pH, and by the presence of organic solvents or sodium dodecyl sulfate (SDS) micelles. However, the hydrodynamic studies suggest that tenecin 3 is not in extended form in spite of its random structural feature.

Animals↗
PubMed1996

Unusually stable helical kink in the antimicrobial peptide--a derivative of gaegurin.

The structure of an active analog of the antibacterial peptide gaegurin was investigated by CD and NMR spectroscopy. The NOE connectivities showed that 21 out of 24 residues formed an a-helix despite the presence of a central proline. CD and NMR analysis indicates that the helix is in fast equilibrium with random coil. From chemical shift analysis of the amide protons, the distances of hydrogen bonding in the helix were calculated, and manifested obvious periodicity which implied a kink in the middle of the helix. 1D amide proton exchange experiments provided further evidence of an exceptionally stable kink. It is inferred that this kink is important not only to the function of the peptide but also to the early stage of the folding as a nucleation site.

Anti-Infective Agents↗
PubMed1996

Serum levels of antioxidant vitamins in relation to coronary artery disease: a case control study of Koreans.

With the changes in trends of disease pattern from infectious to chronic degenerative disease, cardiovascular disease has been considered as the major cause of death in Korea. Numerous studies have been done on the antioxidant effects of some vitamins in the prevention of chronic illness, but not many in relation to the cardiovascular disease. Therefore, the relation between antioxidant vitamins, mainly alpha-tocopherol (alpha-T) and beta-carotene (beta-C), and coronary artery disease (CAD) such as angina pectoris and myocardial infarction has been investigated in this study. The blood samples were obtained from the CAD patients who were angiographically diagnosed within a month (100 case group). Patients who had an experience of PTCA or CABG were excluded from the study. Control subjects were healthy adults who had normal EKG values, no chest pain and no past history of cardiac disease (100 control group). All subjects were free for serum lipid lowering drugs. Serum alpha-T and beta-C were analysed using HPLC. In addition to antioxidant vitamins, serum lipids (total cholesterol, HDL, TG) were also measured. Each case and control was matched in terms of age and sex. And all the CAD risk factors such as blood pressure, smoking, alcohol, serum lipid profile and BMI were adjusted to determine pure effect(s) of alpha-T and beta-C on the CAD. The concentrations of both alpha-T and beta-C were significantly lower in the CAD group than those in control group (P < 0.05); in CAD group, mean values of alpha-T and beta-C were 11.9 +/- 7.2 (micrograms/ml), 35.8 +/- 3.1 (micrograms/dl) respectively. As for the levels of beta-C, it shows inverse relation with age, but not for the alpha-T levels. Serum levels of both vitamins did not show any significant differences in terms of sex, but men have a tendency o higher levels of beta-C, but lower levels of alpha-T.

Adult↗
PubMed1995

Structures of revertant signal sequences of Escherichia coli ribose binding protein.

Recently we reported (Yi et al., 1994) that the alpha-helical content of the signal peptide of Escherichia coli ribose binding protein, when determined by circular dichroism (CD) and two-dimensional NMR in trifluoroethanol/water solvent, is higher than that of its nonfunctional mutant signal peptide. In the present investigation, the structures of the signal peptides of two revertant ribose binding proteins in the same solvent were also determined with CD and two-dimensional 1H NMR spectroscopy. According to the CD results, both of these revertant signal peptides showed an intermediate helicity between those of wild-type and mutant signal peptides, the helical content of the revertant peptide with higher recovery of the translocation capability being higher. On the other hand, the alpha-helix regions of the wild-type and the revertant peptides as determined by NMR were shown to be the same. This discrepancy may be due to the difference in stability between identical alpha-helical stretches in wild-type and revertant peptides. A good correlation was observed between the helical content of these four ribose binding protein signal peptides in TFE/water as studied by CD and their in vivo translocation activities. It appears, therefore, that both the proper length of the helix and the stability are of functional significance.

Amino Acid Sequence↗