Backbone dynamics of a model membrane protein: measurement of individual amide hydrogen-exchange rates in detergent-solubilized M13 coat protein using /sup 13/C NMR hydrogen/deuterium isotope shifts

Journal Article · Tue Jun 16 00:00:00 EDT 1987 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00386a056· OSTI ID:6124527

Henry, G D; Weiner, J H; Sykes, B D

Hydrogen-exchange rates have been measured for individual assigned amide protons in M13 coat protein, a 50-residue integral membrane protein, using a /sup 13/C nuclear magnetic resonance (NMR) equilibrium isotope shift technique. The locations of the more rapidly exchanging amides have been determined. In D/sub 2/O solutions, a peptide carbonyl resonance undergoes a small upfield isotope shift (0.08-0.09 ppm) from its position in H/sub 2/O solutions; in 1:1 H/sub 2/O/D/sub 2/O mixtures, the carbonyl line shape is determined by the exchange rate at the adjacent nitrogen atom. M13 coat protein was labeled biosynthetically with /sup 13/C at the peptide carbonyls of alanine, glycine, phenylalanine, proline, and lysine, and the exchange rates of 12 assigned amide protons in the hydrophilic regions were measured as a function of pH by using the isotope shift method. This equilibrium technique is sensitive to the more rapidly exchanging protons which are difficult to measure by classical exchange-out experiments. In proteins, structural factors, notably H bonding, can decrease the exchange rate of an amide proton by many orders of magnitude from that observed in the freely exposed amides of model peptides such as poly(DL-alanine). With corrections for sequence-related inductive effects, the retardation of amide exchange in sodium dodecyl sulfate solubilized coat protein has been calculated with respect to poly(DL-alanine). The most rapidly exchanging protons, which are retarded very little or not at all, are shown to occur at the N- and C-termini of the molecule. A model of the detergent-solubilized coat protein is constructed from these H-exchange data which is consistent with circular dichroism and other NMR results.

• Research Organization: Univ. of Alberta, Edmonton
• OSTI ID: 6124527
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 26:12; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
AMIDES
BACTERIOPHAGES
BARYONS
BIOCHEMISTRY
CARBON 13
CARBON ISOTOPES
CHEMISTRY
ELEMENTARY PARTICLES
EVEN-ODD NUCLEI
FERMIONS
HADRONS
HEAVY WATER
HYDROGEN COMPOUNDS
ISOTOPES
ISOTOPIC EXCHANGE
LIGHT NUCLEI
MAGNETIC RESONANCE
MICROORGANISMS
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUCLEONS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PARASITES
PROTEINS
PROTONS
RESONANCE
SPECTRA
STABLE ISOTOPES
VIRUSES
WATER