Studies of Methionine Synthesis in Coprinus lagopus

Abstract

When methionine was present in the growth medium of wild-type Coprinus lagopus the incorporation of isotope from S35-sulphate into both cysteine and methionine was greatly decreased. Under these conditions much of the cysteine formed must have arisen from methionine and it is concluded that the diminution of cysteine synthesis from sulphate is caused by the cysteine formed from the methionine and not directly by methionine itself. Wild-type Coprinus accumulated large amounts of cystathionine when grown with methionine and this appeared to have arisen from the added methionine, as isotope from S35-sulphate was not incorporated into the accumulated compound. The cysteine formed from methionine may have been formed from this accumulated cystathionine.