• Title, Summary, Keyword: Helix

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A New Type of Helix Constructed by Plane Curves

  • Choi, Jin Ho
    • Kyungpook Mathematical Journal
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    • v.56 no.3
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    • pp.939-949
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    • 2016
  • In this paper, we give an algorithm to construct a space curve in Euclidean 3-space ${\mathbb{E}}^3$ from a plane curve which is called PDP-helix of order d. The notion of the PDP-helices is a generalization of a general helix and a slant helix in ${\mathbb{E}}^3$. It is naturally shown that the PDP-helix of order 1 and order 2 are the same as the general helix and the slant helix, respectively. We give a characterization of the PDP-helix of order d. Moreover, we study some geometric properties of that of order 3.

ERROR ANALYSIS FOR APPROXIMATION OF HELIX BY BI-CONIC AND BI-QUADRATIC BEZIER CURVES

  • Ahn, Young-Joon;Kim, Philsu
    • Communications of the Korean Mathematical Society
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    • v.20 no.4
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    • pp.861-873
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    • 2005
  • In this paper we approximate a cylindrical helix by bi-conic and bi-quadratic Bezier curves. Each approximation method is $G^1$ end-points interpolation of the helix. We present a sharp upper bound of the Hausdorff distance between the helix and each approximation curve. We also show that the error bound has the approximation order three and monotone increases as the length of the helix increases. As an illustration we give some numerical examples.

Membrane interaction of the coiled-coil motif of HIV gp41 and its implication in the membrane fusion process

  • Jin, Bong-Suk;Yu, Yeon-Gyu
    • Proceedings of the Korean Biophysical Society Conference
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    • pp.58-58
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    • 2003
  • The envelope glycoprotein of HIV, gp41, mediates the membrane fusion with human cells. The extracellular domain of gp41 has two helical regions. The N-terminus helical region (N-helix) forms trimeric coiled coil, interacts with the C-terminus helical region (C-helix) of gp41 to form a stable helical bundle structure. In this study, we have shown that the N-helix of gp41 has membrane interacting and disrupting abilities. It was localized into the interface of the lipidic phase and head group of the membrane. In contrast, the N-helix region with membrane fusion defective mutations could not bind to membrane. In addition, the N-helix bound on the membrane was released from the membrane by the C-helix, and the complex of the N- and C-helix did not interact with membrane. These results suggested that the membrane binding ability of the N-helix is necessary for the fusion activity of gp41, and such property is possibly controlled by the C-helm.

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Solution Structure of the D/E Helix Linker of Skeletal Troponin-C: As Studied by Circular Dichroism and Two-Dimensional NMR Spectroscopy

  • 이원태;G. M. Anatharamaiah;Herbert C. Cheung;N. Rama Krishna
    • Bulletin of the Korean Chemical Society
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    • v.19 no.1
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    • pp.57-62
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    • 1998
  • We have synthesized a 17-residue peptide with the amino acid sequence RQMKEDAKGKSEEELAD corresponding to residues 84-100 of chicken skeletal troponin C. This stretch of the protein sequence is in the middle one-third of the 32-residue 9-turn α-helix that connects the two globular domains of the dumbell-shaped molecule and includes the D/E linker helix. We describe here the solution conformation of the helix linker as studied by circular dichroism (CD) and two-dimensional nuclear magnetic resonance (2-D NMR) spectroscopy. The NOE connectivities together with the vicinal $^3J_{N{\alpha}}$ coupling constants suggest that the peptide exists in a fast conformational equilibrium among several secondary structure: a nascent helix near the N-terminus, a helix, and a substational population of extended and random coil forms. In addition, two interresidue α-α NOEs are observed suggesting a bent structure with a bend that includes the single glycine in position 92. These results are consistent with the ideas that in neutral solution the D/E linker region of the central helix in troponin C can adopt a helical conformation and the central helix may have a segmental flexibility around Gly 92.

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Surgical Ligation of Patent Ductus Arteriosus Using the Descending Aortic Approach in Two Dogs

  • Kim, Dae-Hyun;Hong, Sung-Hwa;Myung, Hyunwook;Son, Dong-ju;Nam, Aryung;Jung, Sung-Yong;Hwang, Jung-Yeon;Jee, Hyun-Choul
    • Journal of Veterinary Clinics
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    • v.37 no.1
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    • pp.42-45
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    • 2020
  • Surgical ligation is the treatment of the choice in patients with patent ductus arteriosus (PDA). This case series presents two cases of PDA, one with and one without persistent left cranial vena cava (PLCVC), treated with surgical ligation through the descending aortic approach with mini-thoracotomy. There were no specific complications during the surgical procedures. The descending aortic approach would be an alternative method for dissection of the PDA.

An Inquiry into the Triple Helix as a New Regional Innovation Model (새로운 지역혁신 모형으로서 트리플 힐릭스에 대한 이론적 고찰)

  • Lee, Chul-Woo;Lee, Jong-Ho;Park, Kyung-Sook
    • Journal of the Economic Geographical Society of Korea
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    • v.13 no.3
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    • pp.335-353
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    • 2010
  • Following the emergence of a knowledge-based economy, the triple helix model has been recognized as a new - regional and national - innovation model. This model seeks to understand the innovation process that is centered upon the university-industry-government interactions. The governance of the triple helix innovation system can be divided into three models according to the structure and depth of university-industry-government interactions. In the context of evolution, the triple helix can be established through the following three processes of development; i) internal transformation of each helix, ii) impacts of one helix on another helix, and iii) horizontal interactions among three helices. In theory, the triple helix model can be covered as part of the innovation system perspective. Compared to the innovation system perspective, the triple helix model tends to pay, however, more attention to the incompleteness of innovation system and the role of university in the process of knowledge creation. In view of regional innovation, the triple helix can be sustained when the triple helix spaces, including knowledge space, consensus space and innovation space, are created and the three triple helix spaces interact with one another. The existing literature on the triple helix model tends to make selectively use of only a single method between the qualitative method and the quantitative method, although both have shortcomings to reveal the dynamic characteristics of university-industry-government relations. Therefore, research on the triple helix is required to reconcile with two research methods, which are distinct but complementary in nature.

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Poly(D-glutamic acid)-Fe(II) Complex Formation and Its Stability Constant (Poly(D-glutamic acid)-Fe(II) 복합물의 형성과 안정도 상수에 관하여)

  • Chong-Su Cho;Seon-Ung Kim
    • Journal of the Korean Chemical Society
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    • v.31 no.5
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    • pp.471-475
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    • 1987
  • Fe(II)-poly(D-glutamic acid) (PGA) complex in aqueous solution has been investigated as functions of pH and concentration of Fe(II) by using absorption and circular dichroism spectroscopies. The helix-breaking interaction occurred at pH 4.3 while the helix-directing one occurred at pH 5.7 after forming complex between PGA and Fe(II). The relationship between conformation change of PGA by forming complex with Fe(II) and complex constants for the above system was studied. As a result, stability constants in random coil structure of PGA are larger than those in ${\alpha}$-helix structure. This result indicates that the random coil structure of PGA-Fe(II) complex shows more stable complex than ${\alpha}$-helix one.

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Role of Helix 8 in Dopamine Receptor Signaling

  • Yang, Han-Sol;Sun, Ningning;Zhao, Xiaodi;Kim, Hee Ryung;Park, Hyun-Ju;Kim, Kyeong-Man;Chung, Ka Young
    • Biomolecules & Therapeutics
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    • v.27 no.6
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    • pp.514-521
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    • 2019
  • G protein-coupled receptors (GPCRs) are membrane receptors whose agonist-induced dynamic conformational changes trigger heterotrimeric G protein activation, followed by GRK-mediated phosphorylation and arrestin-mediated desensitization. Cytosolic regions of GPCRs have been studied extensively because they are direct contact sites with G proteins, GRKs, and arrestins. Among various cytosolic regions, the role of helix 8 is least understood, although a few studies have suggested that it is involved in G protein activation, receptor localization, and/or internalization. In the present study, we investigated the role of helix 8 in dopamine receptor signaling focusing on dopamine D1 receptor (D1R) and dopamine D2 receptor (D2R). D1R couples exclusively to Gs, whereas D2R couples exclusively to Gi. Bioinformatic analysis implied that the sequences of helix 8 may affect GPCR-G protein coupling selectivity; therefore, we evaluated if swapping helix 8 between D1R and D2R changed G protein selectivity. Our results suggest that helix 8 is not involved in D1R-Gs or D2R-Gi coupling selectivity. Instead, we observed that D1R with D2R helix 8 or D1R with an increased number of hydrophobic residues in helix 8 relative to wild-type showed diminished ${\beta}$-arrestin-mediated desensitization, resulting in increased Gs signaling.

Characteristics Design on Helix Angle of the Extruder Screw (압출용 스크루의 나선각에 대한 특성설계)

  • 최부희;최상훈
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.706-709
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    • 1997
  • Extruders are the heart of the polymer processing industry. The single most important mechanical element of a screw extruder is the screw. The proper design of the geometriy of the extruder screw is of crucial importance to the proper functioning of the extruder. If material transport instabilities occur as a result of improper screw geometry, even the most sophisticated computerized control system cannot solve the problem. For this purpose, characteristics design on helix angle of the extruder screw. This paper presents strength of the screw flight, optimum helix angle versus dimensionless down channel pressure gradient, optimum helix angle versus the power law index in simultaneous optimization, volumetric efficiency versus helix angle at various number of flights and power consumption versus helix angle in the barrel of screw extruder.

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A study on the behaviors of acoustic emission and cutting force signals in different helix angle endmillingz (부등각 엔드밀 가공시 음향방출신호와 절삭력 거동에 관한 연구)

  • 김영수;김원일;이윤경;왕덕현
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.239-244
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    • 2002
  • This study shows how the change of helix angle for different helix angle end mill affects machining accuracy. It was verified that cutting forces are remarkably low when endmill has helix angle of different helix angle $25^{\circ}\;, \; 31^{\circ}\; , \; 37^{\circ}$and AE signals have less relationship with the chance of helix angle Moreover, as the number of rotations are increased, the AE signals are increased with the proportion to the number but cutting forces are inversely proportional to the rotation.

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