MYCOTHIOL, O-2'-DEOXY-ALPHA-D-GLUCOPYRANOSYL)-D-MYO-INOSITOL, IS THE FACTOR OF NAD FACTOR-DEPENDENT FORMALDEHYDE DEHYDROGENASE/

Two different NAD/coenzyme-dependent formaldehyde dehydrogenases exist , the well-known NAD/GSH-dependent (EC 1.2.1.1) and the more recently discovered NAD/Factor-dependent enzyme, The GSH-dependent one has been found in eukaryotes and Gram-negative bacteria, the Factor-dependent one in two different Gram-positive bacteria. Previous work also shelve d that Factor and GSH are not interchangeable in the enzymatic reactio ns. Here it is revealed that the Factor is identical to mycothiol (MyS H), 1-O-(2'-[N-acetyl-L-cysteinyl]amido-2' -deoxy-alpha-D-glucopyranos yl)-D-myo-inositol, a thiol compound which has recently been detected in Actinomycetes, Thus, MySH is GSH's companion as it is the coenzyme for the enzyme which henceforth can be indicated as NAD/MySH-dependent formaldehyde dehydrogenase. (C) 1997 Federation of European Biochemic al Societies.