Structural characterization of peptide fragments from hCD81-LEL.
The solution conformation of two peptides [1: PSGSNIISNLFKED; 2: GSSTLTALTTSVLKNNL] from human CD81 (hCD81) large extra-cellular loop (LEL) with known importance in the hepatitis C virus glycoprotein E2 (HCV-E2) binding interaction was characterized using circular dichroism spectroscopy. In addition, the solution structure of peptide 1 that contains a phenylalanine residue (F186 in hCD81) known to be critical in the binding interaction with HCV-E2 was determined using 1D and 2D 1H NMR spectroscopy. Both peptides are unstructured in water but begin forming significant helical conformation following the addition of 20% or more trifluoroethanol (v/v), a result consistent with their alpha-helical conformation found in the native protein. The CD data recorded as a function of pH and NaCl concentration are consistent with stabilization of the helical structure from electrostatic forces for both peptides. Peptide 1 is able to block the binding interaction of recombinant HCV-E2 (rHCV-E2) to hCD81 expressed on Molt-4 T cells at high concentrations (3.5 mM), a low affinity that we attributed to the random coil structure in water.
Dhanasekaran
M
M
Department of Chemistry, Kansas State University, USA.
Baures
P W
PW
VanCompernolle
S
S
Todd
S
S
Prakash
O
O
D000595:Amino Acid Sequence; D015703:Antigens, CD / Q000737:chemistry* / Q000378:metabolism; D002460:Cell Line; D002942:Circular Dichroism; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D060225:Tetraspanin 28; D014759:Viral Envelope Proteins / Q000378:metabolism
D015703:Antigens, CD; C554798:CD81 protein, human; D008565:Membrane Proteins; D010446:Peptide Fragments; D060225:Tetraspanin 28; D014759:Viral Envelope Proteins; C091015:glycoprotein E2, Hepatitis C virus