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Absolute stereochemistry of methanopterin and 5,6,7,8‐tetrahydromethanopterin
Author(s) -
White Robert H.
Publication year - 1996
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/(sici)1520-636x(1996)8:4<332::aid-chir7>3.0.co;2-h
Subject(s) - pterin , chemistry , stereochemistry , circular dichroism , absolute configuration , enzyme , organic chemistry , cofactor
The configuration at the C‐9 of methanopterin (MPT) has been determined by comparing the circular dichroism (CD) spectra of MPT and its hydrolytic fragment, 1‐[4‐[[1‐(2‐amino‐7‐methyl‐4‐hydroxy‐6‐pteridinyl)‐ethyl]amino]phenyl]‐1‐deoxy‐ D ‐ribitol (HP‐1), with the CD spectra of a series of model compounds of known stereochemistry. These compounds included ( S )‐6‐[1‐(4‐carboxymethylanilino)ethyl]pterin, ( S ‐6(1‐hydroxyethyl)‐7‐methylpterin, ( S ‐6‐(1‐hydroxyethyl)pterin, ( R )‐6‐(1‐phenoxyethyl)pterin, D (+)‐neopterin, and L ‐biopterin. From this comparison it was concluded that MPT has the R configuration at C‐9 and is thus configurationally related to D (+)‐neopterin, which has the S configuration at C‐1. From previous work establishing the relative stereochemistry at C‐6, C‐7, and C‐9 of N 5 ‐ N 10 ‐methenyl‐5,6,7,8‐tetrahydromethanopterin ( N 5 ‐ N 10 ‐methenyl‐H 4 MPT) as R , S , and R , respectively, it is clear that the remaining asymmetric carbons at C‐6 and C‐7 of H 4 MPT have the S and S configuration, respectively. Comparison of these latter two positions to the equivalent carbons in 5,6,7,8‐tetrahydrofolate (H 4 folate) show that the steps involved in the biological reduction of MPT to H 4 MPT occur with the same stereochemical outcome as those involved in the biological reduction of folate to H 4 folate. © 1996 Wiley‐Liss, Inc.