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1

Digitale Medien

Larval release in brachyuran crustaceans Functional similarity of peptide pheromone receptor and catalytic site of trypsin (1990)

Rittschof, Dan ; Forward, Richard B. ; Erickson, Bruce W.

Springer

Journal of chemical ecology 16 (1990), S. 1359-1370

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ISSN: 1573-1561

Schlagwort(e): Rhithropanopeus harrisii ; crab ; Crustacea ; larval release pheromone ; peptide pheromone ; trypsin

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Chemie und Pharmazie

Notizen: Abstract Studies of crab egg hatching and larval release behavior in the crab,Rhithropanopeus harrisii, generated a model describing the process. In the model, carboxyl terminal arginine peptides serve as pheromones that synchronize larval release. In response to the peptides, the female performs Stereotypic larval release behavior and casts larvae into the water column. The peptides originate from trypsin-like enzymatic activity as part of the egghatching process. Hatching can be simulated experimentally by incubating ovigerous crabs in either bovine or porcine trypsin. The female performs the larval release behavior. Eggs detach from the female, and immobile larvae hatch prematurely. Preincubation of trypsin with trypsin inhibitors eliminates these effects. Approximately nanomolar concentrations of five different polypeptide trypsin inhibitors evoke the female's larval release behavior. Because both peptides and trypsin inhibitors evoke larval release behavior and because trypsin inhibitors bind to both the peptide receptor and the enzyme with high affinity, the receptor binding site and trypsin catalytic site must be very similar. A relationship between the binding site of a peptide receptor and the catalytic site of trypsin is postulated. The difference may be substitution by a basic amino acid for the catalytic site serine. Molecular graphics modeling indicates that all necessary conditions for receptor binding can be met by substitution with lysine for the active site serine in the trypsin catalytic site. This substitution eliminates catalytic activity, maintains the binding affinity for trypsin inhibitors, and increases binding strength for peptides.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01021032

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2

Digitale Medien

Kinetics of isomerization for the proline helical forms of two oligoproline redox arrays by circular dichroic spectropolarimetry (1999)

Slate, Cheryl A. ; Binstead, Robert A. ; Meyer, Thomas J. ; [weitere]

Springer

International journal of peptide research and therapeutics 6 (1999), S. 61-69

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ISSN: 1573-3904

Schlagwort(e): biexponential kinetics ; proline helices ; substituted proline residues

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Notizen: Abstract The kinetics of isomerization of the helical forms of three oligoprolines was determined by far-ultraviolet CD spectropolarimetry and kinetic analysis by singular value decomposition. ZRA (Pro3-X-Pro2-Y-Pro2-Z-Pro3) and ZRA2 (Pro7-X-Pro2-Y-Pro2-Z-Pro7) bear large redox-active substituents on proline residues X, Y, and Z, but P9 (Pro9) does not. All three peptides formed a stable proline-II helix in water. In acetonitrile, both ZRA2 and P9 were converted into a proline-I helical form but ZRA remained predominantly in the proline-II helical form. Evidently, in order to undergo substantial proline II→I isomerization, an oligoproline chain containing large substituents needs to have a segment of consecutive unsubstituted proline residues that is sufficiently long to form a stable proline helix. Biexponential kinetics (A→B, k1 = ∼3.3 × 10-4 s-1; B→C, k2 = ∼0.8 × 10-4 s-1) were observed for the proline II→I isomerization of ZRA2 and P9 in acetonitrile and for the proline I→II isomerization of ZRA2 in water, which provides evidence for the growth and decay of a major kinetic intermediate.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1008819511721

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3

Digitale Medien

Engineering of deltoid and reduced deltoid: Two chimeric proteins containing the oligomerization site of the hepatitis delta antigen (1999)

Saderholm, Matthew J. ; Erickson, Bruce W.

Springer

International journal of peptide research and therapeutics 6 (1999), S. 23-32

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ISSN: 1573-3904

Schlagwort(e): antiparallel coiled coil ; deltoid ; hepatitis delta antigen ; molecular modeling ; oligomerization site ; protein engineering ; quadrin

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Notizen: Summary Hepatitis delta antigen (HDAg) must form oligomers to be biologically active. Quandrin (HDAg-(12–60)-Tyr) is a 50-residue protein segment from the oligomerization domain of HDAg. The crystal structure of quadrin shows an octamer consisting of four identical copies of a dimer containing an antiparallel α-helical coiled coil. Each end of the dimer contains an oligomerization site that interacts isologously with the oligomerization site of another dimer to form a right-angled corner. The resulting quadrin octamer is a 400-residue square protein surrounding a large aqueous hole. We have designed, chemically synthesized, and characterized deltoid and reduced deltoid, two 51-residue chimeric proteins that structurally and functionally mimic one of the two oligomerization sites of the quadrin dimer. Dimerization of deltoid or reduced deltoid should emulate the dimerization of two quadrin dimers to form one right-angled corner of the square. Deltoid and reduced deltoid were designed by molecular modeling, mechanics, and dynamics and synthesized by the solid-phase method. The amino acid sequence of deltoid (GREDILEQWVSCRKKL+PKAPPEE+LRKLKKKCKKLEEDNPWLGNIKGIIGKY) is a chimera of three protein segments: HDAg-(12–28),Thermus thermophilus serine tRNA synthase-(59–65), and HDAg-(34–60)-Tyr. Cysteine (C) was introduced at two positions to explore the effects of the presence (deltoid) or absence (reduced deltoid) of an interhelical disulfide bond. Circular dichroic spectropolarimetry revealed that both synthetic proteins from an α-helical structure that is stable over a wide range of pH and KCl concentrations. Size-exclusion chromatography indicated that deltoid and reduced deltoid each form a dimer. Interconversion of these monomers and dimers should be useful model systems for studying the structural features of the right-angled corners of the quandrin octamer that contribute to HDAg oligomerization. If, like quadrin, deltoid or reduced deltoid interferes with HDAg oligomerization, it might serve as a lead compound for the design of potent HDV inhibitors.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02443615

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4

Digitale Medien

Synthesis of an iron(II)-braced proline-II tripod protein (1999)

Nakhle, Bassam M. ; Vestal, Tracie L. ; Saderholm, Matthew J. ; [weitere]

Springer

International journal of peptide research and therapeutics 6 (1999), S. 33-43

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ISSN: 1573-3904

Schlagwort(e): 4-amino-l-proline ; circular dichroic spectropolarimetry ; proline-II helix ; protein engineering

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Notizen: Summary This paper describes the engineering of braced tripod proteins for use as molecular frameworks. Specifically, a 30-residue tripod-shaped protein with three proline-II helical legs braced by an iron(II)tris(bipyridine) complex was modularly designed, chemically synthesized, and biophysically characterized. Three copies of a 10-residue leg peptide were covalently linked through sulfide bonds to an N-terminal apex (1,3,5-tris(methylene)benzene) and by amide bonds to the brace (FeII (Mbc)3: Mbc is 4′-methyl-2,2′-bipyridine-4-carbonyl). The leg peptide (H-Cys-Pro5-Pra(Mbc)-Pro3-NH2: Pra iscis-4-amino-l-proline) was assembled by the solid-phase method using Boc-Pra(Mbc)-OH, which was synthesized in 75% overall yield by coupling Mbc-OH to the 4-amino group of Boc-Pra-OCH3 and saponifying the methyl ester group. The iron(II)-braced tripod was assembled by S-alkylation of three copies of the leg peptide with 1,3,5-tris(bromomethyl)benzene followed by ligation of Fe2+ to the resulting unbraced tripod. The CD spectrum of the iron(II)-braced tripod showed a positive MLCT band at 570 nm and a negative π-π* band at 312 nm, so its FeII(Mbc)3 brace was predominantly in the Δ configuration. In a mostly acetonitrile solution at 25°C, the leg peptide and the unbraced tripod isomerized from the proline-II helical form into the proline-I helical form but the iron(II)-braced tripod remained in the proline-II helical form.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02443616

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5

Digitale Medien

Synthesis of an iron(II)-braced proline-II tripod protein (1999)

Nakhle, Bassam M. ; Vestal, Tracie L. ; Saderholm, Matthew J. ; [weitere]

Springer

International journal of peptide research and therapeutics 6 (1999), S. 33-43

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ISSN: 1573-3904

Schlagwort(e): 4-amino-l-proline ; circular dichroic spectropolarimeter ; proline-II helix ; protein engineering

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Notizen: Abstract This paper describes the engineering of braced tripod proteins for use as molecular frameworks. Specifically, a 30-residue tripod-shaped protein with three proline-II helical legs braced by an iron(II)tris(bipyridine) complex was modularly designed, chemically synthesized, and biophysically characterized. Three copies of a 10-residue leg peptide were covalently linked through sulfide bonds to an N-terminal apex (1,3,5-tris(methylene)benzene) and by amide bonds to the brace (FeII(Mbc)3: Mbc is 4′-methyl-2,2′-bipyridine-4-carbonyl). The leg peptide (H-Cys-Pro5-Pra(Mbc)-Pro3-NH2: Pra is cis-4-amino-l-proline) was assembled by the solid-phase method using Boc-Pra(Mbc)-OH, which was synthesized in 75% overall yield by coupling Mbc-OH to the 4-amino group of Boc-Pra-OCH3 and saponifying the methyl ester group.The iron(II)-braced tripod was assembled by S-alkylation of three copies of the leg peptide with 1,3,5-tris(bromomethyl)benzene followed by ligation of Fe2+ to the resulting unbraced tripod. The CD spectrum of the iron(II)-braced tripod showed a positive MLCT band at 570 nm and a negative π–π* band at 312 nm, so its FeII(Mbc)3 brace was predominantly in the Δ configuration. In a mostly acetonitrile solution at 25 °C, the leg peptide and the unbraced tripod isomerized from the proline-II helical form into the proline-I helical form but the iron(II)-braced tripod remained in the proline-II helical form.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1008863326742

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6

Digitale Medien

Engineering of deltoid and reduced deltoid: Two chimeric proteins containing the oligomerization site of the hepatitis delta antigen (1999)

Saderholm, Matthew J. ; Erickson, Bruce W.

Springer

International journal of peptide research and therapeutics 6 (1999), S. 23-32

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ISSN: 1573-3904

Schlagwort(e): antiparallel coiled coil ; deltoid ; hepatitis delta antigen ; molecular modeling ; oligomerization site ; protein engineering ; quadrin

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Notizen: Abstract Hepatitis delta antigen (HDAg) must form oligomers to be biologically active. Quadrin (HDAg-(12–60)-Tyr) is a 50-residue protein segment from the oligomerization domain of HDAg. The crystal structure of quadrin shows an octamer consisting of four identical copies of a dimer containing an antiparallel α-helical coiled coil. Each end of the dimer contains an oligomerization site that interacts isologously with the oligomerization site of another dimer to form a right-angled corner. The resulting quadrin octamer is a 400-residue square protein surrounding a large aqueous hole. We have designed, chemically synthesized, and characterized deltoid and reduced deltoid, two 51-residue chimeric proteins that structurally and functionally mimic one of the two oligomerization sites of the quadrin dimer. Dimerization of deltoid or reduced deltoid should emulate the dimerization of two quadrin dimers to form one right-angled corner of the square. Deltoid and reduced deltoid were designed by molecular modeling, mechanics, and dynamics and synthesized by the solid-phase method. The amino acid sequence of deltoid (GREDILEQWVSCRKKL + PKAPPEE + LRKLKKKCKKLEEDNPWLGNIKGIIGKY) is a chimera of three protein segments: HDAg-(12–28), Thermus thermophilus serine tRNA synthase-(59–65), and HDAg-(34–60)-Tyr. Cysteine (C) was introduced at two positions to explore the effects of the presence (deltoid) or absence (reduced deltoid) of an interhelical disulfide bond. Circular dichroic spectropolarimetry revealed that both synthetic proteins form an α-helical structure that is stable over a wide range of pH and KCl concentrations. Size-exclusion chromatography indicated that deltoid and reduced deltoid each form a dimer. Interconversion of these monomers and dimers should be useful model systems for studying the structural features of the right-angled corners of the quadrin octamer that contribute to HDAg oligomerization. If, like quadrin, deltoid or reduced deltoid interferes with HDAg oligomerization, it might serve as a lead compound for the design of potent HDV inhibitors.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1008811309904

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7

Digitale Medien

Kinetics of isomerization for the proline helical forms of two oligoproline redox arrays by circular dichroic spectropolarimetry (1999)

Slate, Cheryl A. ; Binstead, Robert A. ; Meyer, Thomas J. ; [weitere]

Springer

International journal of peptide research and therapeutics 6 (1999), S. 61-69

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ISSN: 1573-3904

Schlagwort(e): biexponential kinetics ; proline helices ; substituted proline residues

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Notizen: Summary The kinetics of isomerization of the helical forms of three oligoprolines was determined by far-ultraviolet CD spectropolarimetry and kinetic analysis by singular value decomposition. ZRA (Pro3-X-Pro2-Y-Pro2-Z-Pro3) and ZRA2 (Pro7-X-Pro2-Y-Pro2-Z-Pro7) bear large redox-active substituents on proline residues X, Y, and Z, but P9 (Pro9) does not. All three peptides formed a stable proline-II helix in water. In acetonitrile, both ZRA2 and P9 were converted into a proline-I helical form but ZRA remained predominantly in the proline-II helical form. Evidently, in order to undergo substantial proline II→I isomerization, an oligoproline chain containing large substituents needs to have a segment of consecutive unsubstituted proline residues that is sufficiently long to form a stable proline helix. Biexponential kinetics (A→B, k1=∼3.3×10−4s−1; B→C, k2=∼0.8×10−4s−1) were observed for the proline II→I isomerization of ZRA2 and P9 in acetonitrile and for the proline I→II isomerization of ZRA2 in water, which provides evidence for the growth and decay of a major kinetic intermediate.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02443619

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