Gramicidin D

Thereapeutic Function Antibacterial Chemical Name Gramicidin D... 

Another way to increase the entry of Ca2+ across the plasma membrane is to hyperpolarize the plasma membrane by elevating active ion transport. Fischer et al. [130] demonstrated that hyperpolarization of colonic epithelial cells (HT-29) with carbachol elevates the intracellular levels of Ca2+, [Ca2+]i while depolarization with gramicidin D or elevation of K+ in the bathing fluid reverses it. Treatment with 0.1 mM carbachol produced a spontaneous increase in [Ca2+]i from 63 nM to 901 nM. This lasted for about 3 min, beyond which a plateau level of 309 nM was maintained. While the initial Ca2+ transient was present in Ca2+-free medium containing 0.1 mM EGTA, the plateau phase was suppressed to baseline levels, suggesting that carbachol initially releases Ca2+ from the intracellular stores and subsequently increases the Ca2+ entry across the plasma membrane. In cells hyperpolarized with carbachol, induction of depolarization by ele-... 

Chloride channels themselves may directly export drugs, particularly since certain chloride channels appear to act in the same manner as P-glycoprotein (multiple drug resistance protein) [227], which is involved in the export of vincristine [228,229], daunomycin [228,229], gramicidin D [230], and cyclosporin... 

The mixture of gramicidins is called gramicidin [1405-97-6] or gramicidin D (Dubos) [1393-88-0]. The latter name is used to distinguish the gramicidin discovered by Dubos from gramicidins S and J. 

Phospholipid-bilayer membranes with valinomycin, gramicidin D, alamethicin Membrane conductance [29]... 

Gradient materials 924 descent algorithm 731 Gramicidin D 102 Graphite spray 915... 

A D20/lipid ratio of 2 1 (v w) led to easily handled samples and consistent spectroscopic results. Typically, 10 mg of specifically deuterated phospholipid and 20wl D2O were added to a culture tube, which was then sealed and incubated at 55°C for at least 1 hr, with periodic agitation to ensure complete dispersal and hydration. Similar procedures were followed for cholesterol and Gramicidin D-containing samples. Samples were placed between two AgCl windows, and sealed with a 6 pM, spacer. The assembly was wrapped with Teflon tape, as a further seal against dehydration, and inserted into a Harrick cell. Temperature was controlled to + 0.1 C with a Haake circulating water bath and monitored with a thermocouple placed as close as feasible to the point where the IR radiation was focused. 

Incomplete resolution of gauche CD rocking modes along with the occasional presence of incompletely subtracted, weak spectral features arising from cholesterol or Gramicidin D, made curve fitting for quantitative analysis of band intensities necessary. 

Gramicidin D is a naturally occurring mixture of three closely related derivatives,including 87 X Gramicidin A, a pentadecapeptide antibiotic of primary sequence ... 

DPPC/Gramicidin D Mixtures. Experiments to determine the effects of Gramicidin D insertion on lipid conformational order, also illustrate one of the important advantages of the CD2 probe method namely, the ability to discern betveen various sources of disorder (Table V). Spectra of DPPC/Gramicidin mixtures at various... 

Dmole ratios of 6-d, DPPC/Gramicidin D pinole ratio of 12-d /cholesterol = 2 1 tgg class determined by difference... 

Burkhart BM et al (1998) Heterodimer formation and crystal nucleation of gramicidin. D Biopys J 75 2135-2146 PDBID 1ALZ... 

Oradd, G., and G. Lindblom (2004) NMR Studies of lipid lateral diffusion in the DMPC/gramicidin D/water system peptide aggregation and obstruction effects. 

Moll, F., Ill and Cross, T. A. (1990) Optimizing and characterizing alignment of oriented lipid bilayers containing gramicidin D. Biophysical Journal, 57, 351-362. 

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