Serine hydroxymethyltransferase quinonoid intermediate

Depending upon the relative rates of the reactions participating in the interconversion of various species in the ternary complex, one may expect to see spectropho-tometrically the presence of the quinonoid intermediate of type 6 (Fig. 42) in a number of pyridoxal-P-dependent enzymic reactions such an intermediate would be expected to possess a bathochromically shifted long wavelength absorption maximum. This has indeed been clearly viewed for the ternary complex of serine hydroxymethyltransferase with glycine as shown in Fig. 46, the absorption at 495 nm being attributed to the quinonoid intermediate [94]. 

---