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OXIDOREDUCTIVE DEGRADATION OF SOIL MINERALS AND CLAYS D,L‐3(3,4‐DIHYDROXYPHENYL) ALANINE BY SOIL MINERALS AND CLAYS
Author(s) -
MAYAUDON J.,
EL HALFAWI M.,
BATISTIC L.
Publication year - 1973
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1973.tb00754.x
Subject(s) - chemistry , decarboxylation , bentonite , ferric , dithionite , clay minerals , nuclear chemistry , inorganic chemistry , mineralogy , organic chemistry , catalysis , geology , paleontology , enzyme
Summary The effect of the perhydrol (H 2 O 2 ) treated soils on the decarboxylation rate of d,1‐3(3,4‐dihydroxyphenyl) alanine (DOPA), as examined by radiorespirometry, is highly significant and well‐correlated ( r =+0.913) with the clay content. Among the pure Na clays used, Wyoming bentonite had the strongest effect on the DOPA decarboxylation. The reaction was activated by phosphate buffer and completely inhibited by a dithionite treatment. Gas phases like carbon monoxide, hydrogen, or nitrogen do not inhibit the DOPA decarboxylation rate. A chromatographic study of the intermediate products formed during DOPA degradation reveals the presence of 5,6‐dihydroxyindole. These results suggest that DOPA degradation by clays proceeds by a sequence of oxidoreductive reactions following the Raper (1927) scheme. The ferric oxides associated with the clay, and not the dissolved oxygen, are the electron acceptors. DOPA is oxidized to eumelanin which has an elementary percentage composition of C = 62.65; N = 11.05; H = 6.30; 0 = 20.