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Biochemistry. 1999 Nov 16;38(46):15317-24.

Evidence for specific complex formation between alpha-melanocyte stimulating hormone and 6(R)-L-erythro-5,6,7,8-tetrahydrobiopterin using near infrared Fourier transform Raman spectroscopy.

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1
Clinical and Experimental Dermatology, Department of Biomedical Sciences, University of Bradford, West Yorkshire, United Kingdom.

Abstract

The cofactor 6(R)-L-erythro-5,6,7,8-tetrahydrobiopterin (6BH(4)) and its 2 and 4 electron oxidation products 7,8-dihydro-L-biopterin and L-biopterin have been shown to form 1:1 complexes with the thirteen amino acid peptide alpha-melanocyte stimulating hormone (alpha-MSH). Hydrogen bonding to the pyrimidine ring of the cofactor has been established for glu(5) and his(6) of the hormone using Near Infrared Fourier Transform Raman spectroscopy. Binding of these pterins primarily involves the pyrimidine ring, although with the reduced pterins, 7,8-dihydro-L-biopterin and 6BH(4), there is evidence for pi orbital interaction with the pyrazine ring. It is proposed that this pi orbital interaction with the reduced biopterins and alpha-MSH could provide the basis for the observed stability of these pterins to oxidation by either molecular oxygen or photooxidation by UVB (290-320 nm) light. Our results suggest that the formation of the alpha-MSH/6BH(4) complex could play a major role in the control of all 6BH(4) dependent processes.

PMID:
10563817
[Indexed for MEDLINE]
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