9-Fluorenylmethoxycarbonyl amino-protecting group

Carpino, Louis A.; Han, Grace

doi:10.1021/jo00795a005

Cited by 1,053 publications

(560 citation statements)

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“…FMOC-protected glycine, arginine(Pbf), leucine, and tyrosine(tBu) were purchased from LC Sciences (Houston, TX). FMOC-protected alanine, d 4 Free amino acids were protected with FmocOSu according to published procedures [25,26]. Briefly, 1 equivalents of FmocOSu was added to 1 equivalents of NaHCO 3 and 1 equivalents of amino acid in water/acetone.…”

Section: Methodsmentioning

confidence: 99%

Tracking radical migration in large hydrogen deficient peptides with covalent labels: Facile movement does not equal indiscriminate fragmentation

Julian

2009

J. Am. Soc. Mass Spectrom.

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Photodissociation of iodo-tyrosine modified peptides yields localized radicals on the tyrosine side chain, which can be further dissociated by collisional activation. We have performed extensive experiments on model peptides, RGYALG, RGYG, and their derivatives, to elucidate the mechanisms underlying backbone fragmentation at tyrosine. Neither acetylation nor deuteration of the tyrosyl phenolic hydrogen significantly affects backbone fragmentation. However, deuterium migration from the tyrosyl ␤ carbon is concomitant with cleavage at tyrosine. Substitution of tyrosine with 4-hydroxyphenylglycine, which does not have ␤ hydrogens, results in almost complete elimination of backbone fragmentation at tyrosine. These results suggest that a radical situated on the ␤ carbon is required for a-type fragmentation in hydrogen-deficient radical peptides. Replacement of the ␣H of the residue adjacent to tyrosine with methyl groups results in significant diminution of backbone fragmentation. The initial radical abstracts an ␣H from the adjacent amino acid, which is poised to "rebound" and abstract the ␤H of tyrosine through a six-membered transition-state. Subsequent ␤-scission leads to the observed a-type backbone fragment. These results from deuterated peptides clearly reveal that radical migration in peptides can occur and that multiple migrations are not infrequent. Counterintuitively, close examination of all experimental results reveals that the probability for fragmentation at a particular residue is well correlated with thermodynamic radical stability. A-type fragmentation therefore appears to be most likely when favorable thermodynamics are combined with the relevant kinetic control. These results are consistent with ab initio calculations, which demonstrate that barriers to migration are significantly smaller in magnitude than probable dissociation thresholds. (J Am Soc

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Section: Methodsmentioning

confidence: 99%

Tracking radical migration in large hydrogen deficient peptides with covalent labels: Facile movement does not equal indiscriminate fragmentation

Julian

2009

J. Am. Soc. Mass Spectrom.

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“…All other reagents and solvents were purchased from Sigma-Aldrich (Ireland). Peptides were prepared by standard solid-phase peptide synthesis [23] according to the Fmoc-t-Bu strategy [24] characterised by matrix-assisted laser desorption/ionization Time-of-flight (MALDI-TOF) mass spectrometry using the α-cyano-4-hydroxy-cinnamic acid matrix.…”

Section: Peptide Synthesis Purification and Characterisationmentioning

confidence: 99%

High content analysis to determine cytotoxicity of the antimicrobial peptide, melittin and selected structural analogs

et al. 2011

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Antimicrobial peptides (AMPs) are naturally occurring entities with potential as pharmaceutical candidates and/or food additives. They are present in many organisms including bacteria, insects, fish and mammals. While their antimicrobial activity is equipotent with many commercial antibiotics, current limitations are poor pharmacokinetics, stability and potential toxicology issues. Most elicit antimicrobial action via perturbation of bacterial membranes. Consequently, associated cytotoxicity in human cells is reflected by their capacity to lyse erythrocytes. However, more rigorous toxicological assessment of AMPs is required in order to predict potential failure at a later stage of development. We describe a high-content analysis (HCA) screening protocol recently established for determination and prediction of safety in pharmaceutical drug discovery. HCA is a powerful, multi-parameter bioanalytical tool that amalgamates the actions of fluorescence microscopy with automated cell analysis software in order to understand multiple changes in cellular health. We describe the application of HCA in assessing cytotoxicity of the cytolytic α-helical peptide, melittin, and selected structural analogues. The data shows that structural modification of melittin reduces its cytotoxic action and that HCA is suitable for rapidly identifying cytotoxicity.

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“…Therefore, FMOC was added to L-Abu, LApe, and L-Ahx (Sigma) by the procedure of Carpino and Han (1972). This procedure was also used to add FMOC to DL-Ahp (Dixon Fine Chemicals) and to DL-Leu (as a control).…”

Section: Synthesis Of Noncoded Fmoc Amino Acidsmentioning

confidence: 99%

Binding of amino acid side chains to preformed cavities: Interaction of serine proteinases with turkey ovomucoid third domains with coded and noncoded P₁ residues

Bigler

Park

et al. 1993

Protein Science

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In the association of serine proteinases with their cognate substrates and inhibitors an important interaction is the fitting of the PI side chain of the substrate or inhibitor into a preformed cavity of the enzyme called the SI pocket. In turkey ovomucoid third domain, which is a canonical protein proteinase inhibitor, the PI residue is Leu18. Here we report the values of equilibrium constants, K,, for turkey ovomucoid third domain and 13 additional Leul8X variants with six serine proteinases: bovine 01 chymotrypsin A, porcine pancreatic elastase, subtilisin Carlsberg, Streptomyces griseus proteinases A and B, and human leukocyte elastase. Eight of the Xs are coded amino acids: Ala, Ser, Val, Met, Gln, Glu, Lys, and Phe, and five are noncoded: Abu, Ape, Ahx, Ahp, and Hse. They were chosen to simplify the interamino acid comparisons. In the homologous series of straight-chain side chains Ala, Abu, Ape, Ahx, Ahp, free energy of binding decreases monotonically with the side-chain length for chymotrypsin with large binding pocket, but even for this enzyme shows curvature. For the two S. griseus enzymes a minimum appears to be reached at Ahp. A minimum is clearly evident for the two elastases, where increasing the side-chain length from Ahx to Ahp greatly weakens binding, but much more so for the apparently more rigid pancreatic enzyme than for the more flexible leukocyte enzyme. 0-Branching (Ape/Val) is very deleterious for five of the six enzymes; it is only slightly deleterious for the more flexible human leukocyte elastase. The effect of y-branching (Ahx/Leu), of introduction of heteroatoms (Abu/Ser), (Ape/Hse), and (Ahx/Met), and of introduction of charge (Gln/Glu) and (Ahp/Lys) are tabulated and discussed. An important component of the free energy of interaction is the distortion of the binding pocket by bulky or branched side chains.Most of the variants studied were obtained by enzymatic semisynthesis. X" variants of the 6-18 peptide GlyNH, were synthesized and combined with natural reduced peptide 19-56. Disulfide bridges were formed. The GlyNH, was removed and the reactive-site peptide bond Xls-Glu19 was synthesized by complex formation with proteinase K. The resultant complexes were dissociated by sudden pH drop. This kinetically controlled dissociation afforded virgin, reactive-site-intact inhibitor variants.Keywords: binding of amino acid side chains; deformability of binding pockets; enzymatic semisynthesis; noncoded amino acid residues; ovomucoid third domains; serine proteinases Abbreviations: P I , the residue contributing the carbonyl portion to the reactive-site peptide bond; SI, the pocket in the enzyme to which the P I residue binds; OMXXX3, ovomucoid third domain, with XXX designating the species; TKY, turkey; SVP, silver pheasant; SWN, black swan; WTD, West Indian tree duck; MNQ, Montezuma quail; X"OMTKY3, X residue replaces Leu" in OMTKY3 (Fig. 1); Abu CY, aminobutyric acid; Ape CY, aminopentanoic acid (norvaline); Ahx CY, aminohexanoic acid (norleucine); Ahp a , aminoheptanoic acid; H...

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9-Fluorenylmethoxycarbonyl amino-protecting group

Abstract: nmr(CCh) r 2.0-2.2 (m, 2, aromatic), 2.4-2.9 (m, 6, aromatic), 8.00 (s, 1, exchangeable with D20, hydroxyl), and 9.20 (s, 9, iert-butyl); mass spectrum m/e (rel intensity) 254 (0.3, parent), 239 (1), 197 (100), 168 (3), and 152 (6).

Cited by 1,053 publications

References 1 publication

Tracking radical migration in large hydrogen deficient peptides with covalent labels: Facile movement does not equal indiscriminate fragmentation

Tracking radical migration in large hydrogen deficient peptides with covalent labels: Facile movement does not equal indiscriminate fragmentation

High content analysis to determine cytotoxicity of the antimicrobial peptide, melittin and selected structural analogs

Binding of amino acid side chains to preformed cavities: Interaction of serine proteinases with turkey ovomucoid third domains with coded and noncoded P₁ residues

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9-Fluorenylmethoxycarbonyl amino-protecting group

Abstract: nmr(CCh) r 2.0-2.2 (m, 2, aromatic), 2.4-2.9 (m, 6, aromatic), 8.00 (s, 1, exchangeable with D20, hydroxyl), and 9.20 (s, 9, iert-butyl); mass spectrum m/e (rel intensity) 254 (0.3, parent), 239 (1), 197 (100), 168 (3), and 152 (6).

Cited by 1,053 publications

References 1 publication

Tracking radical migration in large hydrogen deficient peptides with covalent labels: Facile movement does not equal indiscriminate fragmentation

Tracking radical migration in large hydrogen deficient peptides with covalent labels: Facile movement does not equal indiscriminate fragmentation

High content analysis to determine cytotoxicity of the antimicrobial peptide, melittin and selected structural analogs

Binding of amino acid side chains to preformed cavities: Interaction of serine proteinases with turkey ovomucoid third domains with coded and noncoded P1 residues

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Binding of amino acid side chains to preformed cavities: Interaction of serine proteinases with turkey ovomucoid third domains with coded and noncoded P₁ residues