Peptide formation in the presence of a metal ion protecting group. 4. Synthesis of penta- and hexapeptide sequences with the pentaamminecobalt(III) complex

Isied, Stephan S.; Vassilian, Asbed; Lyon, John M.

doi:10.1021/ja00378a021

Cited by 31 publications

(5 citation statements)

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“…Inorganic cations that are strongly bound to purple membrane in general do not form bonds that are stable under the conditions of the fragmentation of the protein, the isolation of the resulting peptides, and/or the sequence analysis of the peptides. Yet, a few compounds are applicable to modification of proteins [e.g., Grimes et al (1974)] and were already successfully introduced as an -carboxyl protecting group in peptide synthesis (Isied et al, 1982). In the latter case the cobalt complex [Co(NH3)5H20]3+ was used as cationic reagent in which the water can be replaced by a carboxyl group.…”

Section: Discussionmentioning

confidence: 99%

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Modification of two peptides of bacteriorhodopsin with a (pentaammine)cobalt(III) complex

Engelhard¹,

Pevec²,

Hess³

1989

Biochemistry

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Bacteriorhodopsin (bR) was regenerated from the cation-depleted blue membrane with pentaammineaquocobalt(III) tetrafluoroborate [( Co(NH3)5H2O]3+[BF4-]3). Illumination of the sample with orange light decreased the extinction at 568 nm concomitantly with a hypsochromic shift of the absorption maximum. The photocycle of this sample was inhibited, and the rate of proton pumping was reduced. Chymotryptic cleavage of the corresponding apomembrane into the two fragments C1 and C2 and their subsequent separation revealed that cobalt label is only attached to C1. The maximal incorporation of Co into this peptide was 0.3 Co/C1. After cleavage of C1 with cyanogen bromide and subsequent proteolysis with trypsin and chymotrypsin, this modification could be associated with peptides from cyanogen bromide fragments 6 and 9. The sequences were determined to be 101Val-Asp-Ala-Asp-Gln and 228Ala-Ile-Phe-Gly-Glu-Ala-Glu-Ala. These peptides contain the sequences Asp-Ala-Asp and Glu-Ala-Glu, respectively, which might be constituents of the same cation binding site. The observation that the incorporation of Co into bacteriorhodopsin is enhanced under illumination with orange light indicates that this site might be involved in the proton uptake.

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Section: Discussionmentioning

confidence: 99%

“…Carboxyl groups can be modified by the pentaamminecobalt complex [Co(NH3)5H20]3+ in which the H20 is replaced by a carboxylate (Isied et al, 1982). In this paper the modification of bacteriorhodopsin by this cationic Co complex is described, the labeled peptides are identified, and their sequences are determined.…”

mentioning

confidence: 99%

Modification of two peptides of bacteriorhodopsin with a (pentaammine)cobalt(III) complex

Engelhard¹,

Pevec²,

Hess³

1989

Biochemistry

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“…In the synthesis described in Figure 4, the temporary introduction of another selectively cleavable carboxyl‐protecting group was also required, to allow specific control of the cyclization reactions. For this additional level of carboxyl protection, we chose to use the exchange‐inert cobalt(III) pentaammine complex 52. This group is stable to both acid and base, and is quantitatively cleaved by mild reduction to the exchange‐labile cobalt(II) form in aqueous solution, using (for example) dithiothreitol.…”

Section: Synthetic Approachesmentioning

confidence: 99%

The synthesis and study of side‐chain lactam‐bridged peptides

2002

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Side-chain lactam bridges linking amino acid residues that are spaced several residues apart in the linear sequence offer a convenient and flexible method for introducing conformational constraints into a peptide structure. The availability of a variety of selectively cleavable protecting groups for amines and carboxylic acids allows for several approaches to the synthesis of monocyclic, dicyclic, and bicyclic lactam-bridged peptides by solid-phase methods. Multicyclic structures are also accessible, but segment-condensation syntheses with solution-phase cyclizations are most likely to provide the best synthetic approach to these more complex constrained peptides. Lactam bridges linking (i, i + 3)-, (i, i + 4), and (i, i + 7)-spaced residue pairs have all proven useful for stabilization of alpha helices, and (i, i + 3)-linked residues have also been demonstrated to stabilize beta-turns. These structures are finding an increasing number of applications in protein biology, including studies of protein folding, protein aggregation, peptide ligand-receptor recognition, and the development of more potent peptide therapeutics. Defining the functional roles of the amphiphilic alpha-helices in medium-sized peptide hormones, and studying helix propagation from rigid, alpha-helix initiating bicyclic peptides are among the most exciting developments currently underway in this field.

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“…was prepared as described by Isied et al [16] and was used as starting material for the other ammine complexes.…”

Section: Syntheses Of Cobaltammine Complexesmentioning

confidence: 99%

On the interactions of Ca2+ and cyclosporin A with a mitochondrial inner membrane pore: a study using cobaltammine complex inhibitors of the Ca2+ uniporter

Crompton

Andreeva

1994

Biochemical Journal

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The mitochondrial inner membrane contains a Ca(2+)-activated pore of possible relevance to the pathogenesis of ischaemia/reperfusion injury which is inhibited by the immunosuppressant cyclosporin A (CSA). The present study employs a number of novel cobaltammine complex inhibitors of the Ca2+ uniporter (mediating Ca2+ uptake) to examine whether intramitochondrial Ca2+ influences the capacity of CSA to block the pore. Using dissipation of the inner membrane potential as a means of monitoring the state of the pore, it is shown that CSA blockade is facilitated as Ca2+ uptake is restricted. Ca2+ also depresses and reverses the binding of [3H]CSA to mitochondria, but Ca2+ is ineffective when its uptake is prevented. It is concluded that a high intramitochondrial Ca2+ concentration antagonizes pore inhibition by CSA. The significance of this is discussed.

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Peptide formation in the presence of a metal ion protecting group. 4. Synthesis of penta- and hexapeptide sequences with the pentaamminecobalt(III) complex

Cited by 31 publications

References 1 publication

Modification of two peptides of bacteriorhodopsin with a (pentaammine)cobalt(III) complex

Modification of two peptides of bacteriorhodopsin with a (pentaammine)cobalt(III) complex

The synthesis and study of side‐chain lactam‐bridged peptides

On the interactions of Ca2+ and cyclosporin A with a mitochondrial inner membrane pore: a study using cobaltammine complex inhibitors of the Ca2+ uniporter

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