Sinapinic acid

Sinapinic acid, or sinapic acid (Sinapine - Origin: L. Sinapi, sinapis, mustard, Gr., cf. F. Sinapine.), is a small naturally occurring hydroxycinnamic acid. It is a member of the phenylpropanoid family. It is a commonly used matrix in MALDI mass spectrometry. It is a useful matrix for a wide variety of peptides and proteins. It serves well as a matrix for MALDI due to its ability to absorb laser radiation and to also donate protons (H+) to the analyte of interest.

Sinapic acid can form dimers with itself (one structure) and ferulic acid (three different structures) in cereal cell walls and therefore may have a similar influence on cell-wall structure to that of the diferulic acids.

Sinapine is an alkaloidal amine found in black mustard seeds. It is considered a choline ester of sinapinic acid.

Natural occurrences
Sinapinic acid can be found in wine, vinegar, and black plums.

Metabolism
Sinapate 1-glucosyltransferase is an enzyme that uses UDP-glucose and sinapate to produce UDP and 1-sinapoyl-D-glucose.

Sinapoylglucose—malate O-sinapoyltransferase is an enzyme that uses 1-O-sinapoyl-beta-D-glucose and (S)-malate to produce D-glucose and sinapoyl-(S)-malate.

Related compounds
Canolol is a phenolic compound found in crude canola oil. It is produced by decarboxylation of sinapic acid during canola seed roasting.