Solution structure of the 45-residue MgATP-binding peptide of adenylate kinase as examined by 2-D NMR, FTIR, and CD spectroscopy
The structure of a synthetic peptide corresponding to residues 1-45 of rabbit muscle adenylate kinase has been studied in aqueous solution by two-dimensional NMR, FTIR, and CD spectroscopy. This peptide, which binds MgATP and is believed to represent most of the MgATP-binding site of the enzyme, appears to maintain a conformation similar to that of residues 1-45 in the X-ray structure of intact porcine adenylate kinase, with 42% of the residues of the peptide showing NOEs indicative of phi and psi angles corresponding to those found in the protein. The NMR studies suggest that the peptide is composed of two helical regions of residues 4-7 and 23-29, and three stretches of ..beta..-strand at residues 8-15, 30-32, and 35-40, yielding an overall secondary structure consisting of 24% ..cap alpha..-helix, 38% ..beta..-structure, and 38% aperiodic. Although the resolution-enhanced amide I band of the peptide FTIR spectrum is broad and rather featureless, possible due to disorder, it can be fit by using methods developed on well-characterized globular proteins. The CD spectrum is best fit by assuming the presence of at most 13% ..cap alpha..-helix in the peptide, 24 +/- 2% ..beta..-structure, and 66 +/- 4% aperiodic. The inability of the high-frequency FTIR and CD methods to detect helices in the amount found by NMR may result from the short helical lengths as well as from static and dynamic disorder in the peptide. Upon binding of MgATP, numerous conformation changes in the backbone of the peptide are detected by NMR, with smaller alterations in the overall secondary structure as assess by CD.
- Research Organization:
- Johns Hopkins Univ. School of Medicine, Baltimore, MD (USA)
- OSTI ID:
- 7026705
- Journal Information:
- Biochemistry; (United States), Vol. 27:10
- Country of Publication:
- United States
- Language:
- English
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PHOSPHOTRANSFERASES
CONFORMATIONAL CHANGES
DICHROISM
NUCLEAR MAGNETIC RESONANCE
AQUEOUS SOLUTIONS
ATP
CARBON 14 COMPOUNDS
CATIONS
INFRARED SPECTRA
MAGNESIUM COMPOUNDS
MOLECULAR STRUCTURE
ALKALINE EARTH METAL COMPOUNDS
CHARGED PARTICLES
DISPERSIONS
ENZYMES
IONS
LABELLED COMPOUNDS
MAGNETIC RESONANCE
MIXTURES
NUCLEOTIDES
ORGANIC COMPOUNDS
PHOSPHORUS-GROUP TRANSFERASES
RESONANCE
SOLUTIONS
SPECTRA
TRANSFERASES
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