• Journal of Photoscience
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• 제9권2호
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• pp.114-117
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• 2002

Ultraviolet resonance Raman (UVRR) spectroscopy was used to elucidate the dynamic change of the protein structure of bacteriorhodopsin (BR) during the photocycle. The photointermediates minus light- adapted (LA) BR difference spectra show Trp difference signals, which are assigned to Trp189 or Trp182 on helix F by using the mutants, W182F and W189F. The Difference signals of Trp 182 indicates an increase in hydrogen bonding strength at the indole nitrogen and a large change in the side chain conformation (X$\^$2,1/ torsion angle) in the M$_1$ \longrightarrow M$_2$ transition. On the other hand, Trp189 shows an increased hydrophobic interaction. These results suggest that the tilt of helix F occurs in the M$_1$\longrightarrow M$_2$ transition. In the M$_2$ \longrightarrow N transition, the hydrophobic interaction of Trp182 decreases drastically, The decrease in hydrophobic interaction of Trp182 in the N state suggests an invasion of water molecules that promote the proton transfer from Asp96 to the Schiff base. Structural reorganization of the protein after the tilt of helix F may be important for efficient reprotonation of the Schiff base.

• BMB Reports
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• 제28권3호
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• pp.221-226
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• 1995

Dopamine mediates inhibitory responses in Helix aspersa neurons from the right parietal lobe ("F-lobe") of the circumoesophageal ganglia. The effects appeared as a dose-dependent hyperpolarization of the plasma membrane and a decrease in the occurrence of spontaneous action potentials. The average hyperpolarization with 5 ${\mu}m$ dopamine was -12 mV (${\pm}1.5$mV, S.D., n=12). Dopamine also modulated the currents 'responsible for shaping the action potentials in these neurons. When dopamine was added and action potentials were triggered by an injection of current, the initial depolarization was slowed, the amplitude and the duration of action potentials were decreased, and the after-hyperpolarization was more pronounced. The amplitude and the duration of action potential were reduced about 15 mV and about 13% by 5 ${\mu}m$ dopamine, respectively. The effects of dopamine on the resting membrane potentials and the action potentials of Helix neurons were dose-dependent in the concentration range 0.1 ${\mu}m$ to 50 ${\mu}m$. In order to show 1) that the effects of dopamine were mediated by dopamine receptors rather than by direct action on ionic channels and 2) which type of dopamine receptor might be responsible for the various effects, we assayed the ability of mammalian dopamine receptor antagonists, SCH-23390 (antagonist of D1 receptor) and spiperone (antagonist of D2 receptor), to block the dopamine-dependent changes. The D1 and D2 antagonists partially inhibited the dopamine-dependent hyperpolarization and the decrease in action potential amplitude. They both completely blocked the decrease in action potential duration and the increase in action potential after-hyperpolarization. The dopamine-induced slowdown of the depolarization in the initial phase of the action potentials was less effected by SCH-23390 and spiperone. From the results we suggest 1) that Helix F-lobe neurons may have a single type of dopamine receptor that binds both SCH-23390 and spiperone and 2) that the dopamine receptor of Helix F-lobe neurons may be homologous with and primitive to the family of mammalian dopamine receptors.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제27권2호
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• pp.83-96
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• 2020

In this paper we study Biharmonic curves, Legendre curves and Magnetic curves in three dimensional f-Kenmotsu manifolds. We also study 1-type curves in a three dimensional f-Kenmotsu manifold by using the mean curvature vector field of the curve. As a consequence we obtain for a biharmonic helix in a three dimensional f-Kenmotsu manifold with the curvature κ and the torsion τ, κ² + τ² = -(f² + f'). Also we prove that if a 1-type non-geodesic biharmonic curve γ is helix, then λ = -(f² + f').

• BMB Reports
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• 제40권2호
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• pp.163-171
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• 2007

Functional elements of the conserved helix 7 in the poreforming domain of the Bacillus thuringiensis Cry $\delta$- endotoxins have not yet been clearly identified. Here, we initially performed alanine substitutions of four highly conserved aromatic residues, $Trp^{243}$, $Phe^{246}$, $Tyr^{249}$ and $Phe^{264}$, in helix 7 of the Cry4Ba mosquito-larvicidal protein. All mutant toxins were overexpressed in Escherichia coli as 130-kDa protoxins at levels comparable to the wild-type. Bioassays against Stegomyia aegypti mosquito larvae revealed that only W243A, Y249A or F264A mutant toxins displayed a dramatic decrease in toxicity. Further mutagenic analysis showed that replacements with an aromatic residue particularly at $Tyr^{249}$ and $Phe^{264}$ still retained the high-level toxin activity. In addition, a nearly complete loss in larvicidal activity was found for Y249L/F264L or F264A/ Y249A double mutants, confirming the involvement in toxicity of both aromatic residues which face towards the same direction. Furthermore, the Y249L/F264L mutant was found to be structurally stable upon toxin solubilisation and trypsin digestion, albeit a small change in the circular dichroism spectrum. Altogether, the present study provides for the first time an insight into the highly conserved aromaticity of $Tyr^{249}$ and $Phe^{264}$ within helix 7 playing an important role in larvicidal activity of the Cry4Ba toxin.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2003년도 정기총회 및 학술발표회
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• pp.63-63
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• 2003

$\alpha$$_1$-Antityrpsin is a member of the serine protease inhibitor (SERPIN) family that shares a common tertiary structure. The reactive site loop (RSL) of serpins is exposed at one end of the molecule for protease binding. Upon cleavage by a target protease, the RSL is inserted into the major $\beta$-sheet A, which is a necessary process for formation of a tight inhibitory complex. Various biochemical and structural studies suggest that the rate of the RSL insertion upon binding a target protease is critical for inhibitory activity, and it is thought that helix F region (thFs3A and helix F) located in front of $\beta$-sheet A, should be lifted for the loop insertion during complex formation.

• Bulletin of the Korean Chemical Society
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• 제33권2호
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• pp.583-588
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• 2012

Functional interaction between Drosophila orphan receptor FTZ-F1 (NR5A3) and a segmentation gene product fushi tarazu (FTZ) is crucial for regulating genes related to define the identities of alternate segmental regions in the Drosophila embryo. FTZ binding to the ligand-binding domain (LBD) of FTZ-F1 is of essence in activating its transcription process. We determined solution structures of the cofactor peptide ($FTZ^{PEP}$) derived from FTZ by NMR spectroscopy. The cofactor peptide showed a nascent helical conformation in aqueous solution, however, the helicity was increased in the presence of TFE. Furthermore, $FTZ^{PEP}$ formed ${\alpha}$-helical conformation upon FTZ-F1 binding, which provides a receptor bound structure of $FTZ^{PEP}$. The solution structure of $FTZ^{PEP}$ in the presence of FTZ-F1 displays a long stretch of the ${\alpha}$-helix with a bend in the middle of helix.

• Journal of Contemporary Eastern Asia
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• 제9권2호
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• pp.27-32
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• 2010

• Bulletin of the Korean Chemical Society
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• 제4권1호
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• pp.36-41
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• 1983

An equation is derived which correlates the unperturbed dimensions $_0$ of polypeptides with the helical contents in the helix-coil transition region by using a simple model of a polypeptide chain. The model is a chain of connected balls which represent the repeating units, -CO-NH-CHR-, based on the fact that the repeating unit has a plane structure. The changing trend of the expansion factor ${\alpha}_{\eta}$ in the transition region is connected with the helical content $f_H$. The intrinsic viscosities [${\eta}$] of polypeptides are calculated from the unperturbed dimensions and the ${\alpha}_{\eta}$ factors. The above calculated results concerning $_0$ and [${\eta}$] are compared with other authors' theoretical and experimental results. From the comparison, we concluded that our theory explains better the chain dimensional behavior of polypeptides in the helix-coil transition region than others.

• 한국자기공명학회논문지
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• 제27권4호
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• pp.23-27
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• 2023

Hoxc, or the Homeobox C cluster, is a group of genes that play a crucial role in embryonic development, particularly in patterning the body along the anterior-posterior axis. These genes encode transcription factors, which are proteins that bind to DNA and regulate the expression of other genes. Hoxc9 is specifically involved in the development of the skeletal system, nervous system, and adipose tissue. Hoxc9 overexpression has been linked to the development of various cancers such as leukemia and breast cancer. Here, we assigned the chemical shifts Hoxc9 DNA binding domain (DBD) using heteronuclear NMR techniques. The helical regions of Hoxc9 DBD correspond to the residues T200 - F213 (Helix I), T218 - L229 (Helix II), and T232 - K249 (Helix III). Our result would be helpful for studing the molecular interactions of the Hoxc9 DBD and other proteins.

• 생명과학회지
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• 제12권4호
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• pp.464-468
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• 2002

대장균 트립토판 중합효소(tryptophan synthase) $\alpha$ 소단 위체의 96번, 139번 과 258번 자리를 돌연변이 시킨 이중 돌연변이체 P96L/F139W, P6L/F258W와 삼중 돌연변이체 P96L/F139W/F258W의 효소 활성도와 형광 분광계를 이용한 분광학적 성질을 조사하였다. 이중 돌연변이체의 효소 활성도는 야생형과 유사하나 삼중 돌연변이체는 40% 감소된 활성도를 가진다. P96L/F139W 와 P96L/F258W의 형광세기는 야생형에 비해 감소하였으나 P96L/F139W/F258W는 야생형에 비해 증가하였다. 효소 활성도와 형광 결과는 96번의 치환이 8번 알파구조와 4번 베타 구조와 4번 알파구조 사이의 loop의 안정성에 영향을 준 것을 나타낸다. 이 결과로부터 P96L/F139W/F258W는 야생형과 다른 3차 구조를 가지나 139번과 258면 주위는 더 조밀한 구조를 가지고 있다는 것을 보여준다.