-transparent.png){kind=logo}
The two Z-L-Ala-DL-(alpha Me)Trp-NH2 diastereomeric dipeptides were synthesized from (Z-L-Ala)2(O) and H-DL-(alpha Me)Trp-NH2. The latter racemate, prepared by phase-transfer catalyzed alkylation of the N alpha-benzylidene derivative of alanine amide followed by acidic hydrolysis of the resulting Schiff base, was characterized by X-ray diffraction. The molecular and crystal structure of Z-L-Ala-L-(alpha Me)Trp-NH2, separated from its diastereomer by silica-gel column chromatography, was determined by X-ray diffraction analysis. Both independent molecules in the asymmetric unit of the dipeptide adopt a type-II beta-bend conformation. However, only the more regularly folded conformation of molecule B is stabilized by a 1<--4 C = O...H--N intramolecular H bond. The present results indicate that: (i) the C alpha-methylated (alpha Me)Trp residue is a strong beta-bend and helix former, and (ii) the relationship between (alpha Me)Trp chirality and helix screw sense tends to be opposite to that of protein amino acids. The implications for the use of the (alpha Me)Trp residue in designing conformationally restricted analogs of bioactive peptides are briefly discussed.
F Formaggio, and
C Toniolo, and
M Crisma, and
G Valle, and
B Kaptein, and
H E Schoemaker, and
J Kamphuis, and
B Di Blasio, and
O Maglio, and
R Fattorusso
May 1991,
Biopolymers,
F Formaggio, and
C Toniolo, and
M Crisma, and
G Valle, and
B Kaptein, and
H E Schoemaker, and
J Kamphuis, and
B Di Blasio, and
O Maglio, and
R Fattorusso
February 1983,
International journal of peptide and protein research,
F Formaggio, and
C Toniolo, and
M Crisma, and
G Valle, and
B Kaptein, and
H E Schoemaker, and
J Kamphuis, and
B Di Blasio, and
O Maglio, and
R Fattorusso
August 1980,
International journal of peptide and protein research,
F Formaggio, and
C Toniolo, and
M Crisma, and
G Valle, and
B Kaptein, and
H E Schoemaker, and
J Kamphuis, and
B Di Blasio, and
O Maglio, and
R Fattorusso
January 2003,
Biopolymers,
F Formaggio, and
C Toniolo, and
M Crisma, and
G Valle, and
B Kaptein, and
H E Schoemaker, and
J Kamphuis, and
B Di Blasio, and
O Maglio, and
R Fattorusso
February 2000,
Acta crystallographica. Section B, Structural science,
F Formaggio, and
C Toniolo, and
M Crisma, and
G Valle, and
B Kaptein, and
H E Schoemaker, and
J Kamphuis, and
B Di Blasio, and
O Maglio, and
R Fattorusso
June 1991,
International journal of peptide and protein research,
F Formaggio, and
C Toniolo, and
M Crisma, and
G Valle, and
B Kaptein, and
H E Schoemaker, and
J Kamphuis, and
B Di Blasio, and
O Maglio, and
R Fattorusso
January 2001,
Journal of peptide science : an official publication of the European Peptide Society,
F Formaggio, and
C Toniolo, and
M Crisma, and
G Valle, and
B Kaptein, and
H E Schoemaker, and
J Kamphuis, and
B Di Blasio, and
O Maglio, and
R Fattorusso
April 1975,
The Journal of pharmacy and pharmacology,
F Formaggio, and
C Toniolo, and
M Crisma, and
G Valle, and
B Kaptein, and
H E Schoemaker, and
J Kamphuis, and
B Di Blasio, and
O Maglio, and
R Fattorusso
February 1969,
The Journal of pharmacy and pharmacology,
F Formaggio, and
C Toniolo, and
M Crisma, and
G Valle, and
B Kaptein, and
H E Schoemaker, and
J Kamphuis, and
B Di Blasio, and
O Maglio, and
R Fattorusso
June 1973,
The Journal of pharmacy and pharmacology,
