Document Detail

Special transport and neurological significance of two amino acids in a configuration conventionally designated as D.
MedLine Citation:
PMID:  7823029     Owner:  NLM     Status:  MEDLINE    
We point out an ability of certain amino acids to be recognized at a biological receptor site as though their amino group bore, instead of an alpha relationship to a carboxylate group, a beta, gamma or delta relationship to the same or a second carboxylate group. For aspartate, the unbalanced position of its amino group between a pair of carboxylates allows its occasional biorecognition as a beta-rather than as an alpha-amino acid, whereas for proline and its homologs, their cyclic arrangement may allow the imino group, without its being replicated, to be sensed analogously as falling at either of two distances from the single carboxylate group. The greater separation might allow proline to be seen as biologically analogous to gamma-aminobutyric acid. This more remote positioning of the imino group would allow the D-form of both amino acids to present its amino group in the orientation characteristic of the natural L-form. The dual modes of recognition should accordingly be signalled by what appears to be low stereospecificity, actually due to a distinction in the enantiorecognition of the two isomers. Competing recognition for transport between their respective D- and L-forms, although it does not prove that phenomenon, has been shown for proline and, significantly, even more strongly for its lower homolog, 2-azetidine carboxylate. Such indications have so far revealed themselves rather inconspicuously for the central nervous system binding of proline, reviewed here as a possible feature of a role suspected for proline in neurotransmission.
H N Christensen; A A Greene; D K Kakuda; C L MacLeod
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Publication Detail:
Type:  Comparative Study; Journal Article; Review    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  196     ISSN:  0022-0949     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  1994 Nov 
Date Detail:
Created Date:  1995-02-16     Completed Date:  1995-02-16     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  297-305     Citation Subset:  IM    
Graduate Program in Biomedical Sciences, University of California at San Diego, La Jolla 92093-0609.
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MeSH Terms
Aspartic Acid / analogs & derivatives,  chemistry,  metabolism*
Binding, Competitive
Biological Transport
Central Nervous System / metabolism*
Proline / analogs & derivatives,  chemistry,  metabolism*
Structure-Activity Relationship
gamma-Aminobutyric Acid / metabolism
Reg. No./Substance:
147-85-3/Proline; 56-12-2/gamma-Aminobutyric Acid; 56-84-8/Aspartic Acid

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