The biosynthesis of vitamin K will be investigated, the major emphasis being on the production of menaquinones in Escherichia coli and Mycobacterium phlei. Some work will be done on phylloquinone production by plants. The biosynthetic pathway as presently understood in bacteria is likely: chorismate plus alpha-ketoglutarate yields succinylbenzoate yields 1,4-dihydroxy-2-naphthoate yields demethylmenaquinone yields menaquinone. Bacterial extracts will be examined for the enzyme producing succinylbenzoate (""""""""succinylbenzoate synthetase"""""""") which has not yet been described. Initially the assay system will be to follow conversion of labeled chorismate to possible products. Experiments are planned to determine whether the actual substrate is chorismate and whether alpha-ketoglutarate is utilized by way of the semialdehyde-thiamin pyrophosphate complex. The purification of the naphthoate synthetase system will be continued. A major question for this enzyme is the possible role of a succinylbenzoate-Coenzyme A complex. It is also planned to investigate the late enzymes of the pathway, and to determine their localization within the bacterial cell. These enzymes are a prenyltransferase and a methylase. The sequence in which these two steps occur will be determined. Plant extracts will be examined for the presence and utilization of dihydroxynaphthoate and for the presence of enzyme systems similar to those known to be present in bacteria.
