(β-Asp5)-Delta-Sleep Inducing Peptide (DSIP-isoD) is a synthetic polypeptide that can be partially hydrolyzed by NaOH or SDS. (β-Asp5)-Delta-Sleep Inducing Peptide can be used to study the catalytic activity of mitochondrial protein L-isoaspartyl (D-aspartyl) methyltransferase (PIMT).

His-[D-2-ME-Trp]-Ala is a fragment of the growth hormone hexarelin.

4-Methylumbelliferyl-α-D-Glucopyranoside (4-Methylumbelliferyl-α-D-Glucose) is a fluorescent substrate for α-glucosidase, which releases the fluorescent moiety 4-methylumbelliferyl (4-MU) upon cleavage. 4-MU has pH-dependent fluorescence excitation activity, with excitation wavelengths of 320 nm at low pH (1.97-6.72) and 360 nm at high pH (7.12-10.3), respectively. The emission wavelength of 4-Methylumbelliferyl-α-D-Glucopyranoside increases with decreasing pH, ranging from 445-455 nm. 4-Methylumbelliferyl-α-D-Glucopyranoside can be used as a biomarker for Fabry and Pompe diseases to quantify α-glucosidase activity in infant blood spot samples.