Solution structure of trypsin modulating oostatic factor is a left-handed helix.
The solution structure of trypsin modulating oostatic factor (TMOF), a decapeptide (H-YDPAPPPPPP-OH) hormone that signals the termination of trypsin-like biosynthesis in mosquito midgut epithelial cells, was determined by 2-D 1H nuclear magnetic resonance spectroscopy and molecular modeling. The peptide forms a rod-shaped left-handed helix about 30 A long. No evidence was found to support a poly-L-proline beta-turn model. Hydrophobic contacts between the rings of tyrosine 1 and proline 3 may enhance the stability of the N-terminal segment. This peptide provides an interesting exception to the normal chemical shift index (csi) rules. Our results suggest that a sequence of positive csi indices, normally expected for a beta-strand structure, could also describe a left-handed poly-L-proline-like helix.
Comprehensive Cancer Center, University of Alabama, Birmingham 35294.
E V
EV
Curto
M A
MA
Jarpe
J E
JE
Blalock
D
D
Borovsky
N R
NR
Krishna
D000595:Amino Acid Sequence; D006859:Hydrogen; D009682:Magnetic Resonance Spectroscopy; D008961:Models, Structural; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry*; D017433:Protein Structure, Secondary; D012996:Solutions
D009842:Oligopeptides; D012996:Solutions; C065612:Peptide oostatic hormone; D006859:Hydrogen