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Inhibition of alcohol dehydrogenases by thiol compounds
Author(s) -
Cheng Li-Yao,
Lek Lee-Hua
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)80856-c
Subject(s) - thiol , alcohol , chemistry , alcohol dehydrogenase , biochemistry , alcohol oxidoreductase , enzyme , nad+ kinase
2‐Mercaptoethanol is a strong inhibitor of LADH. The inhibitory effect is likely due to the binding of the SH group to the enzymatic zinc ion. Various thiol compounds do not inhibit YADH and it is suggested that the zinc atoms involved in the catalytic mechanism of LADH and YADH may have different structural arrangements and that these zinc atoms in YADH may not be blocked by thiol compounds. Thiol compounds also quench the enhanced fluorescence of LADH‐NADH in a pH‐dependent manner. At pH 9.2, the binding of coenzyme to LADH is replaced by 2‐mercaptoethanol, whilst at pH 7.3, it further quenches the fluorescence of NADH‐LADH. This quenching of fluorescence is likely attributed to a conformational change and energy transfer upon binding of 2‐mercaptoethanol to the LADH‐NADH complex. Complete reversal of the inhibitory effect of thiol compounds on LADH can be obtained by dialysis.