AQUA™ Peptides for Absolute Quantitation

Experience AQUA™ Peptides for Yourself . . .

1. Identify the best tryptic peptide for your application. We advise performing a tryptic digest on your protein of interest and analyzing by HPLC-MS. This will help determine the best candidate based on peptide resolution and ionization.
2. Determine the sequence of the chosen peptide. Generally, peptides should be fewer than 15 residues long. (If your peptide is longer, prices may increase.)
   
3. Determine the appropriate stable isotope labeled amino acid to incorporate from the stable isotope labeled amino acids available for
   AQUA™ peptides. One residue will be stable isotopically labeled.
4. Send us your order specifications.

Place your custom AQUA™ Peptide order

Send us your order specifications.
Contact us for any technical assistance.

Available in 20-25 business days

When placing your order, please have the following information ready:

• Peptide sequence
• Stable isotope labeled amino acid of choice
• Required modifications (i.e., post-translational modification)
• Number of packages
• Shipping/Billing address
• Purchase order or credit card number
• Telephone number
• E-mail address

Table 1. Custom AQUA™ Peptide

Product Description	# of peptides x vials x amount	Price
Custom AQUA™ Peptide (quantitated by AAA)	1 x 5 x 1 nmol	$500

Selecting the Best AQUA™ Peptide

Using the known specificity of trypsin, list all of the tryptic peptides contained in your protein of interest. From these candidate peptides, select the best AQUA™ peptide for your studies using the guidelines listed below.

• Choose a tryptic peptide which resolves well by HPLC. Avoid peptides that are too hydrophilic or too hydrophobic.
  
• Choose a peptide which ionizes well.
  
• Avoid chemically reactive residues (Tryptophan, Methionine, Cysteine), or chemically unstable sequences (Asp-Gly, N-term Gln, N-term Asn).
  
• Peptide sequence length should be limited to 15 amino acids or less.
  
• Choose a peptide containing an amino acid well-suited to stable isotope labeling, for which the mass difference will be 5 or greater.

Table 2. Stable Isotope Labeled Amino Acid Options

Stable Isotope Labeled Amino Acid (Fully Labeled, 13C, 15N > 98 atom%)	Mass Difference between Native Peptide and AQUA™ Peptide
L-Arginine-13C6, 15N4	10 Daltons
L-Isoleucine-13C6, 15N	7 Daltons
L-Leucine-13C6, 15N	7 Daltons
L-Lysine-13C6, 15N2	8 Daltons
L-Phenylalanine-13C9, 15N	10 Daltons
L-Proline-13C5, 15N	6 Daltons
L-Valine-13C5, 15N	6 Daltons