dAMP + S-adenosyl-L-methionine => 4'-phospho-dehydrooxetanocin + 5'-deoxyadenosine + L-methionine + H(+)
damp + s-adenosyl-l-methionine => 4'-phospho-dehydrooxetanocin + 5'-deoxyadenosine + l-methionine + h(+)