Pentadecapeptide

Naturally occurring gramicidin is a mixture of at least six linear pentadecapeptide antibiotics of closely related structure produced by Bacillus brevis 207). The amino acid sequence of the major component [Valjgramicidin A was reported by Sarges and Witkop208 in 1965 ... 

Polzhofer, K. P. 1972. Synthesis of a rennin-sensitive pentadecapeptide from cow /(-casein. Tetrahedron 28, 855-865 (German). 

What is required is that the chemical shift change appreciably between acid and base forms. Because 13C, 15N, 19F, and 31P chemical shifts are dispersed over a large range, there is usually at least one suitable reporter nucleus near enough to the site of protonation, and even H chemical shifts show sufficient variation. Thus the pKa of glycine could be measured from the inflection points in the pD dependence of its H or 13C chemical shifts.12 Similarly, from the variation with pH of the 13C chemical shifts of acetic, propionic, and butyric acids the pKa of each acid could be measured.13 The separate pifas of four lysines in a pentadecapeptide could be measured from the pH... 

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

M+H)+ of a derivative of the linear pentadecapeptide and antibiotic Val-gramicidicin A, a transmembrane protein this derivative has structure formyl-NH-V-G-A-L-A-V-V-V-W-L-W-L-W-L-W-ethanolamine. The CID (collision-induced dissociation) spectrum is very similar to a MALDI/TOF spectrum. Figure 11.10 shows the PSD of ACTH, the adenocorticotropic hormone. 

By use of a synthetic pentadecapeptide corresponding to the amino-terminal region of Bombyx PITH, a monoclonal antibody that specifically recognized Bombyx PITH was prepared. Immunohistochemistry of Bombyx brains using this antibody revealed that two pairs of dorso-lateral neurosecretory cells were immunoreactive (Mizoguchi, et aK in preparation). 

Gramicidin /I is a linear pentadecapeptide which has frequently served as a model for an internal protein. IR spectroscopy shows that above the transition temperature... 

The pentadecapeptide Met-f -sulfoxide (20 mg, 0.01 mmol) was incubated in 1% aq thioglycolic acid (25 mL) at 45 °C for 24 h, the thioglycolic acid was then exchanged for acetate on an IRA-400 column by eluting with H2O. Freshly distilled thioglycolic acid was added to make a 1% soln. The incubation and ion exchange steps were carried out three times and the final aq soln was lyophilized yield 20 mg (92 %) amino acid analysis of the aminopeptidase M digest confirmed quantitative reduction of the Met(O) residue. 

Peptides (pentadecapeptide, hexadecapeptide, poly-L-lysiue) Organic acids (oxaloacetic, citric, isocitric, pirivic)... 

Extension of dermorphin with residues from the precursor sequence also yields potent p-selective peptides. Although introduction of the additional residues through the Glu or Ala residues decreases p-receptor affinity, apparently because of introduction of the acidic Glu residue, further extension of the sequence increases p-receptor affinity as basic residues are incorporated (872) the resulting pentadecapeptide (Tyr-o-Ala-Phe-Gly-Tyr-Pro-Ser-Gly-Glu-Ala-Lys-Lys-Ile-Lys-Arg-NH2) has exceptional affinity for /x receptors... 

Stereochemical and experimental studies of GA led to proposals that this L,D-pentadecapeptide is capable of adopting single-stranded (Urry,... 

Figure 34. A, Circular dichroism spectra of the Gramicidin A transmembrane channel in phospholipid bilayers (curve a) and of hydrogenated Gramicidin A in trifluoroethanol at high concentration ( 100 mg/ml), which is likely a double-stranded j3-helix. See text for discussion. Mean residue ellipticities are given. B, Absorption spectrum of the Gramicidin A transmembrane channel in phospholipid bilayers. The absorption spectrum is dominated by the four tryptophan residues per pentadecapeptide. The extinction coefficient is given on a per residue basis.

These results verified the results obtained with totally randomized undecapeptide libraries and pentadecapeptide libraries characterized by one position occupied by D-ami-no acids [21]. Interestingly, TAP can accommodate peptides with bulky or non natural side chains, and even branched peptides [21,22]. 

Various lipophilic natural product antibiotics that have a hydrophobic exterior and a shielded hydrophilic interior capable of binding and transporting ions are known as ionophores. The three ionophores that are most commonly used as probes of ion transport across mitochondrial membranes are the Streptomyces cyclic dodecadepsipeptide valinomycin (57), gramicidin pentadecapeptides (e.g., valine-gramicidin A,... 

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