Phase labeling of C-H and C-C spin-system topologies: Application in constant-time PFG-CBCA(CO)NH experiments for discriminating amino acid spin-system types

Carlos B. Rios, Wenqing Feng, Mitsuru Tashiro, Zhigang Shang, Gaetano T. Montelione

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

Triple-resonance experiments facilitate the determination of sequence-specific resonance assignments of medium-sized 13C, 15N-enriched proteins. Some triple-resonance experiments can also be used to obtain information about amino acid spin-system topologies by proper delay tuning. The constant-time PFG-CBCA(CO)NH experiment allows discrimination between five different groups of amino acids by tuning (phase labeling) independently the delays for proton-carbon refocusing and carbon-carbon constant-time frequency labeling. The proton carbon refocusing delay allows discrimination of spin-system topologies based on the number of protons attached to Cα and Cβ atoms (i.e. C-H phase labeling). In addition, tuning of the carbon-carbon constant-time frequency-labeling delay discriminates topologies based on the number of carbons directly coupled to Cα and Cβ atoms (i.e. C-C phase labeling). Classifying the spin systems into these five groups facilitates identification of amino acid types, making both manual and automated analysis of assignments easier. The use of this pair of optimally tuned PFG-CBCA(CO)NH experiments for distinguishing five spin-system topologies is demonstrated for the 124-residue bovine pancreatic ribonuclease A protein.

Original languageEnglish (US)
Pages (from-to)345-350
Number of pages6
JournalJournal of biomolecular NMR
Volume8
Issue number3
DOIs
StatePublished - 1996

ASJC Scopus subject areas

  • Biochemistry
  • Spectroscopy

Keywords

  • Automated analysis of NMR data
  • Protein NMR
  • Pulsed-field gradient
  • Resonance assignments
  • Triple resonance

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