Isocyanide binding to the copper(I) centers of the catalytic core of peptidylglycine monooxygenase (PHMcc)

Francis C. Rhames, Narasimha N. Murthy, Kenneth D. Karlin, Ninian Blackburn

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Binding of the Cu(I)-specific ligands 2,6-dimethylphenyl isocyanide (DIMPI) and isopropyl isocyanide (IPI) to the reduced form of peptidylglycine monooxygenase (PHM) is reported. Both ligands bind to the methionine-containing CuM center, eliciting FTIR bands at 2138 and 2174 cm-1, respectively, but appear unable to coordinate at the histidine-containing CuH center in the wild-type enzyme. This chemistry parallels that previously observed for CO binding to the reduced PHM catalytic core (PHMcc). However, in contrast to the CO chemistry, peptide substrate binding did not induce binding of the isocyanide at CuH. XAS confirmed the binding of DIMPI at CuM via the observation of a short Cu-C interaction at 1.87 Å and by the lengthening of the Cu-S(methionine) bond length by 0.06 Å. Similarly, FTIR studies on DIMPI binding to the M314I and H172A mutant forms of reduced PHMcc confirmed the assignment of the 2138-cm-1 IR band as a CuM-DIMPI complex, but surprisingly also showed DIMPI binding to CuH, as indicated by a band at 2148 cm-1. An inorganic complex, [Cu(1,2-Me2Im)2(DIMPI)](PF6), was synthesized and its crystal structure was determined as a model for the interaction of isocyanides with imidazole-containing Cu(I) complexes. Comparison of EXAFS data for the protein and model suggests that DIMPI probably binds to CuM in a tilted fashion, similar to that of ethyl isocyanide binding to myoglobin.

Original languageEnglish (US)
Pages (from-to)567-577
Number of pages11
JournalJournal of Biological Inorganic Chemistry
Volume6
Issue number5-6
DOIs
StatePublished - 2001

Fingerprint

Cyanides
Copper
Catalytic Domain
Fourier Transform Infrared Spectroscopy
Carbon Monoxide
Methionine
Ligands
Myoglobin
Bond length
peptidylglycine monooxygenase
2,6-dimethylphenyl isocyanide
Histidine
Crystal structure
Observation
Peptides
Substrates
Enzymes
Proteins

Keywords

  • Copper isocyanides
  • Fourier transform infrared spectroscopy
  • Peptidylglycine monooxygenase
  • X-ray absorption spectroscopy

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry

Cite this

Isocyanide binding to the copper(I) centers of the catalytic core of peptidylglycine monooxygenase (PHMcc). / Rhames, Francis C.; Murthy, Narasimha N.; Karlin, Kenneth D.; Blackburn, Ninian.

In: Journal of Biological Inorganic Chemistry, Vol. 6, No. 5-6, 2001, p. 567-577.

Research output: Contribution to journalArticle

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abstract = "Binding of the Cu(I)-specific ligands 2,6-dimethylphenyl isocyanide (DIMPI) and isopropyl isocyanide (IPI) to the reduced form of peptidylglycine monooxygenase (PHM) is reported. Both ligands bind to the methionine-containing CuM center, eliciting FTIR bands at 2138 and 2174 cm-1, respectively, but appear unable to coordinate at the histidine-containing CuH center in the wild-type enzyme. This chemistry parallels that previously observed for CO binding to the reduced PHM catalytic core (PHMcc). However, in contrast to the CO chemistry, peptide substrate binding did not induce binding of the isocyanide at CuH. XAS confirmed the binding of DIMPI at CuM via the observation of a short Cu-C interaction at 1.87 {\AA} and by the lengthening of the Cu-S(methionine) bond length by 0.06 {\AA}. Similarly, FTIR studies on DIMPI binding to the M314I and H172A mutant forms of reduced PHMcc confirmed the assignment of the 2138-cm-1 IR band as a CuM-DIMPI complex, but surprisingly also showed DIMPI binding to CuH, as indicated by a band at 2148 cm-1. An inorganic complex, [Cu(1,2-Me2Im)2(DIMPI)](PF6), was synthesized and its crystal structure was determined as a model for the interaction of isocyanides with imidazole-containing Cu(I) complexes. Comparison of EXAFS data for the protein and model suggests that DIMPI probably binds to CuM in a tilted fashion, similar to that of ethyl isocyanide binding to myoglobin.",
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T1 - Isocyanide binding to the copper(I) centers of the catalytic core of peptidylglycine monooxygenase (PHMcc)

AU - Rhames, Francis C.

AU - Murthy, Narasimha N.

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AU - Blackburn, Ninian

PY - 2001

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N2 - Binding of the Cu(I)-specific ligands 2,6-dimethylphenyl isocyanide (DIMPI) and isopropyl isocyanide (IPI) to the reduced form of peptidylglycine monooxygenase (PHM) is reported. Both ligands bind to the methionine-containing CuM center, eliciting FTIR bands at 2138 and 2174 cm-1, respectively, but appear unable to coordinate at the histidine-containing CuH center in the wild-type enzyme. This chemistry parallels that previously observed for CO binding to the reduced PHM catalytic core (PHMcc). However, in contrast to the CO chemistry, peptide substrate binding did not induce binding of the isocyanide at CuH. XAS confirmed the binding of DIMPI at CuM via the observation of a short Cu-C interaction at 1.87 Å and by the lengthening of the Cu-S(methionine) bond length by 0.06 Å. Similarly, FTIR studies on DIMPI binding to the M314I and H172A mutant forms of reduced PHMcc confirmed the assignment of the 2138-cm-1 IR band as a CuM-DIMPI complex, but surprisingly also showed DIMPI binding to CuH, as indicated by a band at 2148 cm-1. An inorganic complex, [Cu(1,2-Me2Im)2(DIMPI)](PF6), was synthesized and its crystal structure was determined as a model for the interaction of isocyanides with imidazole-containing Cu(I) complexes. Comparison of EXAFS data for the protein and model suggests that DIMPI probably binds to CuM in a tilted fashion, similar to that of ethyl isocyanide binding to myoglobin.

AB - Binding of the Cu(I)-specific ligands 2,6-dimethylphenyl isocyanide (DIMPI) and isopropyl isocyanide (IPI) to the reduced form of peptidylglycine monooxygenase (PHM) is reported. Both ligands bind to the methionine-containing CuM center, eliciting FTIR bands at 2138 and 2174 cm-1, respectively, but appear unable to coordinate at the histidine-containing CuH center in the wild-type enzyme. This chemistry parallels that previously observed for CO binding to the reduced PHM catalytic core (PHMcc). However, in contrast to the CO chemistry, peptide substrate binding did not induce binding of the isocyanide at CuH. XAS confirmed the binding of DIMPI at CuM via the observation of a short Cu-C interaction at 1.87 Å and by the lengthening of the Cu-S(methionine) bond length by 0.06 Å. Similarly, FTIR studies on DIMPI binding to the M314I and H172A mutant forms of reduced PHMcc confirmed the assignment of the 2138-cm-1 IR band as a CuM-DIMPI complex, but surprisingly also showed DIMPI binding to CuH, as indicated by a band at 2148 cm-1. An inorganic complex, [Cu(1,2-Me2Im)2(DIMPI)](PF6), was synthesized and its crystal structure was determined as a model for the interaction of isocyanides with imidazole-containing Cu(I) complexes. Comparison of EXAFS data for the protein and model suggests that DIMPI probably binds to CuM in a tilted fashion, similar to that of ethyl isocyanide binding to myoglobin.

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KW - X-ray absorption spectroscopy

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