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An NMR Study on the Conformation of Substance P in Acidic Bicelles
Baek, Seung-Bin,Lim, Sung-Chul,Lee, Hyeong-Ju,Lee, Hee-Cheon,Kim, Chul Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.10
The conformation of a neuropeptide, substance P (SP), in isotropic (q = 0.5) acidic bicelles was investigated using two-dimensional NMR techniques. By the nuclear Overhauser effect (NOE) cross peaks between SP and long-chain lipid molecules SP was probed to bind on the flat surface of the disc-like bicelles. Structural analysis of NMR data indicated that the helical conformation of SP extended to the C-terminal region of Leu10 as well as in the mid-region from Pro4 to Phe8. As compared with the conformations of SP bound on the sodium dodecylsulfate (SDS) or the dodecylphosphocholine (DPC) micelles with curved surfaces, the surface curvature of the membrane mimics was found to be one of the major factors inducing the biologically relevant conformation of SP. The negative surface charge of the membrane is also a key factor inducing both the binding of SP on the membrane and its biologically active structure.
Thermodynamics of Partitioning of Substance P in Isotropic Acidic Bicelles
Baek, Seung Bin,Lee, Hyeong Ju,Lee, Hee Cheon,Kim, Chul Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.3
The temperature dependence of the partition coefficients of a neuropeptide, substance P (SP), in isotropic acidic bicelles was investigated by using a pulsed field gradient nuclear magnetic resonance diffusion technique. The addition of negatively charged dimyristoylphosphatidylserine to the neutral bicelle changed the SP partitioning a little, which implies that the hydrophobic interaction between the hydrophobic residues of SP and the acyl chains of lipid molecules is the major interaction while the electrostatic interaction is minor in SP binding in a lipid membrane. From the temperature dependence of the partition coefficients, thermodynamic functions were calculated. The partitioning of SP into the acidic bicelles is enthalpy-driven, as it is for small unilamellar vesicles and dodecylphosphocholine micelles, while peptide partitioning into a large unilamellar vesicle is entropy-driven. This may mean that the size of lipid membranes is a more important factor for peptide binding than the surface curvature and surface charge density.
Thermodynamics of partitioning of substance P in isotropic bicelles
Kim, Chul,Baek, Seung Bin,Kim, Do Hun,Lim, Sung Chul,Lee, Hyeong Ju,Lee, Hee Cheon John Wiley Sons, Ltd. 2009 Journal of peptide science Vol.15 No.5
<P>The temperature dependence of the partition of a neuropeptide, substance P (SP), in isotropic (q = 0.5) bicelles was investigated by using pulsed field gradient NMR diffusion technique. The partition coefficient decreases as the temperature is increased from 295 to 325 K, indicating a favorable (negative) enthalpy change upon partitioning of the peptide. Thermodynamic analysis of the data shows that the partitioning of SP at 300 K is driven by the enthalpic term (ΔH) with the value of − 4.03 kcal mol<SUP>−1</SUP>, while it is opposed by the entropic term (−TΔS) by approximately 1.28 kcal mol<SUP>−1</SUP> with a small negative change in heat capacity (ΔC<SUB>p</SUB>). The enthalpy-driven process for the partition of SP in bicelles is the same as in dodecylphosphocholine (DPC) micelles, however, the negative entropy change in bicelles of flat bilayer surface is in sharp contrast with the positive entropy change in DPC micelles of highly curved surface, indicating that the curvature of the membrane surface might play a significant role in the partitioning of peptides. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd.</P>
( Sung Jin Moon ),( Hyun Jung Kim ),( Sung Bin Cho ),( Seung Hun Lee ),( Hoon Young Choi ),( Hyeong Cheon Park ),( Sung Kyu Ha ) 대한전해질학회 2014 Electrolytes & Blood Pressure Vol.12 No.2
Uremic pruritus is a common problem in patients with end-stage renal disease (ESRD), but the underlying mechanisms are not yet fully understood. We aimed to investigate the association between severity of uremic pruritus and cutaneous serine protease activity, as well as proteinase-activated receptor-2 (PAR-2) ex- pression. Twelve ESRD patients with pruritus, 4 ESRD patients without pruritus, and 6 healthy controls were enrolled. Skin biopsies were obtained from the abdomen. Protease activity and PAR-2 expression in the epidermis were examined by in situ zymography and confocal laser microscopy, respectively. All ESRD patients presented more pronounced cutaneous protease activity compared with that in healthy controls. The skin samples from the patients with pruritus showed higher protease activity than either nonpruritic ESRD patients or healthy controls. The epidermis in all samples of ESRD patients presented higher immunoreactivity against PAR-2 versus those of healthy controls. In addition, correlation analysis between PAR-2 expression and VAS pruritus scores showed a significant positive correlation. Our data suggests that levels of serine protease and PAR-2 expression could play important roles in the pathogenesis of uremic pruritus.