Perosamine

Perosamine is a 4-aminodeoxysugar that is found in the O-antigen of Vibrio cholarae O1 and E. coli O157:H7. Its biosynthesis from mannose follows a pathway similar to that of colitose, but is different in that it is aminated and does not undergo a C-5 epimerization.

The final enzyme in the pathway, GDP-D-perosamine synthase, is a PLP-dependent enzyme that transfers an amino group from glutamate to the C-4 position of the sugar.