5,231 research outputs found
I Was Addicted to Sex With Married Women
No full textAs a young man, Akhil Sharma revelled in the most dangerous of liaisons, having sex with other men's wives – until the thrill began to pall
Maldives Resorts: Eco-Friendly Vacations
No full textLuxurious, exclusive and remote, the Maldives are the ultimate beach escape. They’re also a case study in the risks of global warming. Writer Akhil Sharma visits the country’s most eco-friendly resorts and discovers a remarkable cuisine worth protecting
Recollections of a Hindu Hedonist
No full textNovelist Akhil Sharma grew up in a teetotaling Indian household. Here, he tells how discovering a passion for great wine helped him create a new identity out of a painful past
Interview with Lakshmi Raj Sharma, Author of The Tailor’s Needle
No full textInterview with Indian writer Lakshmi Raj Sharma, author of 'The Tailor's needle
Effects of nociceptin and analogues of nociceptin upon spontaneous dorsal root activity recorded from an in vitro preparation of rat spinal cord
No full textThe 17 amino acid peptide nociceptin has been implicated in pain modulation in the central nervous system. The effects of bath applied
nociceptin, and some analogues of nociceptin, upon spontaneous lumbar dorsal root activity have been investigated in an isolated preparation
of rat spinal cord. Nociceptin was found to reversibly depress spontaneous dorsal root activity at concentrations of 1.0 mMand 10.0 mM(IC50
2.0 mM), whereas acetyl-nociceptin at concentrations up to 10 mMhad no detectable effect. Omission of the last four amino acids (nociceptin
1–13), increased the potency of the effect upon dorsal root activity by approximately 100-fold (IC50 30 nM), but activity was lost when only
the first seven amino acids of the nociceptin molecule (nociceptin 1–7) were tested
Self-association of model transmembrane alpha-helices is modulated by lipid structure
No full textWe have developed a fluorescence quenching method using peptides containing 3,5-dibromotryrosine to measure oligomerization of model transmembrane a-helices in lipid bilayers. Peptides of the type Ac-LysLysGlyLeu(m)XLeu(n)LysLysAla-amide where X is tryptophan or 3,5-dibromotyrosine were found to form heterodimers in bilayers of phosphatidylcholine in the liquid-crystalline phase. The free energy of dimer formation changed little with increasing number of Leu residues from 16 to 22 but increased with increasing phospholipid fatty acyl chain length, with a slope of about 0.5 kJ mol(-1) per fatty acyl chain carbon. Peptides were excluded from lipid in the gel phase, resulting in increased levels of oligomerization. Addition of cholesterol to form the liquid-ordered state led to increased dimerization but without phase separation. The presence of phosphatidylethanolamine had little effect on dimerization
Effects of aromatic residues at the ends of transmembrane alpha-helices on helix interactions with lipid bilayers
No full textWe have studied the effects of aromatic residues at the ends of peptides of the type Ac-KKGLnWLmKKA-amide on their interactions with lipid bilayers as a function of lipid fatty acyl chain length, physical phase, and charge. Peptide Ac-KKGFL6WL8FKKA-amide (F2L14) incorporated into bilayers of phosphatidylcholines containing monounsaturated fatty acyl chains of lengths C14-C24 at a peptide:lipid molar ratio of 1:100 in contrast to Ac-KKGL7WL9KKA-amide (L16) which did not incorporate at all into dierucoylphosphatidylcholine [di(C24:1)PC]; Ac-KKGYL6WL8YKKA-amide (Y2L14) incorporated partly into di(C24:1)PC. Lipid-binding constants relative to that for dioleoylphosphatidylcholine (C18:1)PC were obtained using a fluorescence quenching method. For Y2L14 and F2L14, relative lipid-binding constants increased with increasing fatty acyl chain length from C14 to C24; strongest binding did not occur at the point where the hydrophobic length of the peptide equalled the hydrophobic thickness of the bilayer. For Ac-KKGYL9WL11YKKA-amide (Y2L20), increasing chain length from C18 to C24 had little effect on relative binding constants. Anionic phospholipids bound more strongly than zwitterionic phospholipids to Y2L14 and Y2L20 but effects of charge were relatively small. In two phase (gel and liquid crystalline) mixtures, all the peptides partitioned more strongly into liquid crystalline than gel phase; effects were independent of the structure of the peptide or of the lipid (dipalmitoylphosphatidylcholine or bovine brain sphingomyelin). Addition of cholesterol had little effect on incorporation of the peptides into lipid bilayers. It is concluded that the presence of aromatic residues at the ends of transmembrane -helices effectively buffers them against changes in bilayer thickness caused either by an increase in the chain length of the phospholipid or by the presence of cholesterol
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