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PDBsum entry 2glg
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Hormone/growth factor
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PDB id
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2glg
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References listed in PDB file
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Key reference
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Title
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Structural determinants of salmon calcitonin bioactivity: the role of the leu-Based amphipathic alpha-Helix.
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Authors
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G.Andreotti,
B.L.Méndez,
P.Amodeo,
M.A.Morelli,
H.Nakamuta,
A.Motta.
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Ref.
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J Biol Chem, 2006,
281,
24193-24203.
[DOI no: ]
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PubMed id
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Abstract
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Salmon calcitonin (sCT) forms an amphipathic helix in the region 9-19, with the
C-terminal decapeptide interacting with the helix (Amodeo, P., Motta, A.,
Strazzullo, G., Castiglione Morelli, M. A. (1999) J. Biomol. NMR 13, 161-174).
To uncover the structural requirements for the hormone bioactivity, we
investigated several sCT analogs. They were designed so as to alter the length
of the central helix by removal and/or replacement of flanking residues and by
selectively mutating or deleting residues inside the helix. The helix content
was assessed by circular dichroism and NMR spectroscopies; the receptor binding
affinity in human breast cancer cell line T 47D and the in vivo hypocalcemic
activity were also evaluated. In particular, by NMR spectroscopy and molecular
dynamics calculations we studied Leu(23),Ala(24)-sCT in which Pro(23) and
Arg(24) were replaced by helix inducing residues. Compared with sCT, it assumes
a longer amphipathic alpha-helix, with decreased binding affinity and one-fifth
of the hypocalcemic activity, therefore supporting the idea of a relationship
between a definite helix length and bioactivity. From the analysis of other sCT
mutants, we inferred that the correct helix length is located in the 9-19 region
and requires long range interactions and the presence of specific regions of
residues within the sequence for high binding affinity and hypocalcemic
activity. Taken together, the structural and biological data identify well
defined structural parameters of the helix for sCT bioactivity.
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Figure 3.
FIGURE 3. A, stereo view of the backbone superposition of
the 100 Leu^23,Ala^24-sCT periodically sampled structures along
the 1000-ps unrestrained MD. Structures were superimposed for
pairwise minimum r.m.s. deviation of the N, C  , and C
atoms of residues 4–28. B, stereo view of Leu^23,Ala^24-sCT
structure showing the amphipathic property of the -helix;
hydrophobic residues, mainly leucine, are on the left side,
whereas hydrophilic amino acids are on the right side. Hydrogen
bonds along the backbone and in the N and C terminus helix cap
motifs are represented as discontinuous lines.
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Figure 5.
FIGURE 5. -Helical content of CT
mutants in SDS as obtained from the NMR qualitative pattern
recognition approach (see "Results"). Horizontal bars symbolize
the helix, a square represents a substitution, whereas a cross
indicates a deletion within the sequence. Mutants are labeled as
in Tables 1 and 2. The region corresponding to the putative
biologically relevant helix is shaded.
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2006,
281,
24193-24203)
copyright 2006.
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Secondary reference #1
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Title
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Solution conformation of salmon calcitonin in sodium dodecyl sulfate micelles as determined by two-Dimensional nmr and distance geometry calculations.
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Authors
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A.Motta,
A.Pastore,
N.A.Goud,
M.A.Castiglione morelli.
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Ref.
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Biochemistry, 1991,
30,
10444-10450.
[DOI no: ]
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PubMed id
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Secondary reference #2
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Title
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Conformational flexibility in calcitonin: the dynamic properties of human and salmon calcitonin in solution.
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Authors
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P.Amodeo,
A.Motta,
G.Strazzullo,
M.A.Castiglione morelli.
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Ref.
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J Biomol Nmr, 1999,
13,
161-174.
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PubMed id
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