Fig. 4. Derivatives of non–CoA bound G3P were captured by the sensor peptide.

(A) A possible mechanism for detection of G3P as N-lactyl-peptide is via pyruvaldehyde, which is known to be generated from G3P and can undergo rearrangement with thiols to form lactyl-thioesters. (B) Pyruvaldehyde can also undergo pH-dependent aldol condensation to yield a six-carbon species that overlaps in mass with the desired HMG product.