Solid-state NMR studies of the dynamics and structure of mouse keratin intermediate filaments

Journal Article · Tue Jul 26 04:00:00 EDT 1988 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00415a006· OSTI ID:6828094

Mack, J W; Torchia, D A; Steinert, P M

The molecular dynamics and structural organization of mouse epidermal keratin intermediate filaments (IF) have been studied via solid-state nuclear magnetic resonance (NMR) experiments performed on IF labeled both in vivo and in vitro with isotopically enriched amino acids. As a probe of the organization of the peripheral glycine-rich end domains of the IF, carbon-13 NMR experiments have been performed on subfilamentous forms (prekeratin) and on IF reassembled in vitro that had been labeled with either (1-/sup 13/C)glycine or (2-/sup 13/C)glycine, as more than 90% of the glycines of the keratins are located in the end domains. Measurements of carbon relaxation times, nuclear Overhauser enhancements, and signal intensities show that the motions of the peptide backbone in the end domains are effectively isotropic. These results indicate that the end domains of IF are remarkably flexible and have little or no structural order. To probe the structural organization of the coiled-coil rod domains of the IF, separate samples of native keratin IF, raised in primary tissue culture, were labeled with L-(1-/sup 13/C)leucine, L-(/sup 2/H/sub 10/)leucine, or L-(2,3,3-/sup 2/H/sub 3/)leucine, as greater than 90% of the leucyl residues of the keratin IF types studied are located in the coiled coils which form the central core of IF. Deuterium NMR experiments performed on IF labeled with deuteriated leucines indeed reveal a marked degree of peptide backbone rigidity within the coiled coils, confirming the initial conclusions of the carbon-13 data. These data, demonstrating relative peptide backbone rigidity yet side-chain flexibility, are interpreted to mean that the coiled coils of these keratin IF are not tightly packed together but rather form a somewhat looser structure which permits a significant degree of side-chain mobility.

• Research Organization: National Institutes of Health, Bethesda, MD (USA)
• OSTI ID: 6828094
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 27:15; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
AMINO ACIDS
ANIMAL TISSUES
ANIMALS
BODY
CARBON 13
CARBON ISOTOPES
CARBOXYLIC ACIDS
DEUTERIUM COMPOUNDS
EPIDERMIS
EPITHELIUM
EVEN-ODD NUCLEI
GLYCINE
HYDROGEN COMPOUNDS
ISOTOPES
KERATIN
LEUCINE
LIGHT NUCLEI
MAGNETIC RESONANCE
MAMMALS
MICE
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
OVERHAUSER EFFECT
PROTEIN STRUCTURE
PROTEINS
RESONANCE
RODENTS
SCLEROPROTEINS
SKIN
SPECTRA
STABLE ISOTOPES
TISSUES
VERTEBRATES