The role of S-adenosyl-n-methionine as a methyl donor has been investigated in mammalian systems (1) and in microbial metabolism (2-4). In addition, the compound is involved in the formation of spermidine from putrescine (5). Information concerning the stability of S-adenosylmethionine in various enzymatic systems is a necessary prerequisite for studies concerning its role in group transfer. In...

The methyltetrahydrofolate:corrinoid/iron-sulfur protein methyltransferase (MeTr) enzyme was originally isolated from the acetogenic bacteria Moorella (formerly Clostridium) thermoaceticum [612]. This bacterium, as some other anaerobic organisms, can obtain its entire carbon and energy source from CO or H2/CO2 by the Wood-Ljungdahl or acetyl-CoA pathway [613-615]. Initially, CO2 is reduced to f...

The HhaI methyltransferase recognizes the sequence GCGC and transfers a methyl group to C5 of the first cytosine residue. All m5C-methyltransferases contain a highly conserved sequence motif called the P-C motif. The cysteine residue of this motif is involved in catalysis by forming a covalent bond with the 6-position of cytosine prior to methyl group transfer. For the EcoRII methyltransferase,...

The chemically most complex modification in eukaryotic rRNA is the conserved hypermodified nucleotide N1-methyl-N3-aminocarboxypropyl-pseudouridine (m(1)acp(3)Ψ) located next to the P-site tRNA on the small subunit 18S rRNA. While S-adenosylmethionine was identified as the source of the aminocarboxypropyl (acp) group more than 40 years ago the enzyme catalyzing the acp transfer remained elusive...

Quantum mechanical calculations at the B3LYP/6-311+G(d,p) level have examined the overall mechanism of the Baeyer-Villiger (BV) reaction with peroxyacetic acid. A series of reactions that include both the addition step and the subsequent alkyl group migration step included ketones, acetone, t-butyl methyl ketone, acetophenone, cyclohexyl methyl ketone, and cyclohexyl phenyl ketone. The combined...

DNA methyltransferases are enzymes that specifically recognize a target sequence (typically four to six bases long) on a DNA double strand. They transfer a methyl group from Sadenosyl-L-methionine to a specific position on a specific base of their target sequence. These enzymes can be divided into two major classes, according to the position methylated. Either the methyl group is transfered ont...