TY - JOUR
T1 - Distribution of distances between the tryptophan and the N‐terminal residue of melittin in its complex with calmodulin, troponin C, and phospholipids
AU - Lakowicz, Joseph R.
AU - Gryczynski, Ignacy
AU - Laczko, Gabor
AU - Wiczk, Wieslaw
AU - Johnson, Michael L.
PY - 1994/4
Y1 - 1994/4
N2 - We used frequency‐domain measurements of fluorescence resonance energy transfer to measure the distribution of distances between Trp‐19 of melittin and a 1‐dimethylamino‐5‐sulfonylnaphthalene (dansyl) residue on the N‐terminal‐α‐amino group. Distance distributions were obtained for melittin free in solution and when complexed with calmodulin (CaM), troponin C (TnC), or palmitoyloleoyl‐L‐α‐phosphatidylcholine (POPC) vesicles. A wide range of donor (Trp‐19)‐to‐acceptor (dansyl) distances was found for free melittin, which is consistent with that expected for the random coil state, characterized by a Gaussian width (full width at half maxima) of 28.2 Å. In contrast, narrow distance distributions were found for melittin complexed with CaM, 8.2 Å, or with POPC vesicles, 4.9 Å. A somewhat wider distribution was found for the melittin complex with TnC, 12.8 Å, suggesting the presence of heterogeneity in the mode of binding between melittin and TnC. For all the complexes the mean Trp‐19 to dansyl distance was near 20 Å. This value is somewhat smaller than expected for the free α‐helical state of melittin, suggesting that binding with CaM or TnC results in a modest decrease in the length of the melittin molecule.
AB - We used frequency‐domain measurements of fluorescence resonance energy transfer to measure the distribution of distances between Trp‐19 of melittin and a 1‐dimethylamino‐5‐sulfonylnaphthalene (dansyl) residue on the N‐terminal‐α‐amino group. Distance distributions were obtained for melittin free in solution and when complexed with calmodulin (CaM), troponin C (TnC), or palmitoyloleoyl‐L‐α‐phosphatidylcholine (POPC) vesicles. A wide range of donor (Trp‐19)‐to‐acceptor (dansyl) distances was found for free melittin, which is consistent with that expected for the random coil state, characterized by a Gaussian width (full width at half maxima) of 28.2 Å. In contrast, narrow distance distributions were found for melittin complexed with CaM, 8.2 Å, or with POPC vesicles, 4.9 Å. A somewhat wider distribution was found for the melittin complex with TnC, 12.8 Å, suggesting the presence of heterogeneity in the mode of binding between melittin and TnC. For all the complexes the mean Trp‐19 to dansyl distance was near 20 Å. This value is somewhat smaller than expected for the free α‐helical state of melittin, suggesting that binding with CaM or TnC results in a modest decrease in the length of the melittin molecule.
KW - calmodulin
KW - distance distributions
KW - fluorescence spectroscopy
KW - frequency‐domain fluorescence
KW - melittin
KW - protein conformation
KW - protein folding
KW - resonance energy transfer
KW - troponin C
UR - http://www.scopus.com/inward/record.url?scp=0028327234&partnerID=8YFLogxK
U2 - 10.1002/pro.5560030411
DO - 10.1002/pro.5560030411
M3 - Article
C2 - 8003981
AN - SCOPUS:0028327234
SN - 0961-8368
VL - 3
SP - 628
EP - 637
JO - Protein Science
JF - Protein Science
IS - 4
ER -