Complete stereochemistry of neamphamide A and absolute configuration of the beta-methoxytyrosine residue in papuamide B.
The absolute stereochemistry of the three unresolved structural components in neamphamide A (1) was determined to be (R)-beta-methoxy-L-tyrosine, (2R,3R,4S)-4-amino-7-guanidino-2,3-dihydroxyheptanoic acid, and (2R,3R,4R)-3-hydroxy-2,4,6-trimethylheptanoic acid. Stereochemical assignments were made by chemical degradation of 1, derivatization of the resulting products, and then spectroscopic and chromatographic comparison of the derivatives with synthetically prepared standards. Using the same analytical protocol developed for 1, the beta-methoxytyrosine residue in papuamide B (2) was found to be (R)-beta-methoxy-D-tyrosine. This represents a rare example of divergent stereochemistry in an unusual amino acid residue that is present in two closely related classes of peptides.
Oku
Naoya
N
Molecular Targets Development Program, Center for Cancer Research, National Cancer Institute, Building 1052, Room 121, Frederick, MD 21702-1201, USA.
Krishnamoorthy
Ravi
R
Benson
Alan G
AG
Ferguson
Robert L
RL
Lipton
Mark A
MA
Phillips
Lawrence R
LR
Gustafson
Kirk R
KR
McMahon
James B
JB
D047630:Depsipeptides / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D010456:Peptides, Cyclic / Q000737:chemistry*; D013237:Stereoisomerism; D014443:Tyrosine / Q000031:analogs & derivatives / Q000737:chemistry*
D047630:Depsipeptides; D010456:Peptides, Cyclic; C492416:neamphamide A; C474171:papuamide B; D014443:Tyrosine