chemical symmetry in life

[POSTMASTER at NBRF.GEORGETOWN.EDU]

In message <Pine.3.87.9403291659.B19054-0100000 at unamvm1.dgsca.unam.mx>
Magidin Viso Monica (monica at unamvm1.dgsca.unam.mx) asks:
> Hello, I don't know where I got the information that there are some 
> arthropods that have d-aminoacids instead of l-aminoacids (as almost any 
> living thing does), does anyone know if this information is correct? I am 
> confused since the arthropods are not a very distant group from the rest 
> of the animals or invertebrates, as to have this big basic difference. 

D-amino acids are, so far as is currently known, not genetically encoded
by any organism on earth.  Besides small, non-genetically encoded peptides
found in bacteria, fungi and some other organisms, D-amino acids do occur
as post-translational modifications of a few genetically encoded proteins.
The only examples presently annotated in the PIR-International Protein
Sequence Database are D-alanine and D-methionine in demorphin from
Phyllomedusa sauvagei (Sauvage's leaf frog).  Another soon to be annotated
example is D-phenylalanine in achatin-I from Achatina fulica (giant African
snail).
------------------------------------------------------------------------
                                 Dr. John S. Garavelli
                                 Database Coordinator
                                 Protein Information Resource
                                 National Biomedical Research Foundation
                                 Washington, DC  20007
                                 POSTMAST at GUNBRF.BITNET
                                 POSTMASTER at NBRF.GEORGETOWN.EDU