Leu-Enkephalin purified peptide can be used for calibration of mass spectrometers. Leu-Enkephalin peptide mass standard gives a monoisotopic mass of 556.277 [M + H]+ and average mass of 556.6 [M + H]+. Dissolve the Leu-Enkephalin peptide with buffer or matrix solution right in the tube then analyze by MALDI-MS or ESI-MS.

Molecular Weight: 555.6

Monoisotopic Mass [M+H]+: 556.277

Amino Acid Sequence: Tyr-Gly-Gly-Phe-Leu