How pure are Tocris Bioscience products?

Unless otherwise stated, the purity of our products is estimated to be > 98%.

How stable are Tocris Bioscience products?

Due to the novelty of many of our products, information concerning product stability, particularly in solution, has rarely been reported and in most cases we can only offer a general guide. When information is known we do our best to publish this in the catalogue or on the data sheets that accompany our products. Our standard recommendations are:

Solid:	Provided storage is as stated on the product label and the vial is kept tightly sealed, the product can be stored for up to 6 months
Solutions:	We recommend that stock solutions, once prepared, are stored in tightly sealed vials at -20°C. Generally these will be useable for up to one month. Wherever possible solutions should be made up and used on the same day.

Will shipping conditions affect shelf-life?

Many of our products are refrigerated or frozen for long-term storage. Short periods at higher temperatures (periods < 1 week), as might occur during shipping, will not affect product life or efficacy.

How does Tocris Bioscience advise dissolving products?

The solubility data provided for each product is accurate to the best of our knowledge. However, solutions of some products can be difficult to obtain. Solubility can often be encouraged by rapid stirring, sonication or gentle warming. Please do not hesitate to contact us if you require additional solubility information.

How do I prepare a sloution using equivalents (eq) of sodium hydroxide (NaOH)?

Aqueous solutions of some amino acids can be difficult to achieve, so a common technique is to use 1 molar equivalents (1eq.) of sodium hydroxide (NaOH) as a solubility aid.

We generally recommend that a 100 mM sodium hydroxide solution is used to dissolve the active compound. One litre of 100 mM NaOH solution is made up by dissolving 4.00 g of sodium hydroxide in 1 litre of water.

Take the molecular weight (M.W.) of the compound as detailed on the vial label and data sheet and calculate the amount in grams (M.W./10) required to form a 100 mM solution when 1L solvent is added (X). From this, calculate the amount in grams required to form a 100 mM solution when 1 ml solvent is added (X/1000). 1 ml of the NaOH stock solution prepared above can now be added to this weight to dissolve the compound. In some cases warming of the solution or sonication may aid solubilisation.

Example Glutamic acid (Catalogue Number 0217) M.W.: 147.13 For 100 mM solution: M.W./10 = 14.7 g in 1L For amount needed to make 1 ml of a 100 mM solution: 14.7/1000 = 14.7 x 10-3 g in 1 ml = 14.7 mg in 1 ml Weigh 14.7 mg glutamic acid add 1 ml NaOH (100 mM) = 1 ml of a 100 mM solution of glutamic acid in 1eq. NaOH This solution can then be further diluted (with water) to the required concentration.

Note: When preparing solutions of up to 100 mM with 1.1 equivalents of NaOH, simply make up a 110 mM stock solution of NaOH and then follow the protocol as above.

Does Tocris Bioscience sell peptides by net peptide weight?

All peptides sold by Tocris Bioscience are supplied by net peptide weight. As sold, peptides may contain counterions and residual water. Therefore, although the purity of a particular peptide may be quoted as that of 98%, the net peptide content may only be 70%. To compensate for this our peptides are weighed so that the amount of peptide received is exactly that stated on the vial. For example, for 1 mg of a peptide with 70% net content, 1.43 mg of material (1/0.7) is actually supplied.

How pure are Tocris Bioscience peptides?

Unless otherwise stated, peptides supplied by Tocris Bioscience have a purity of > 95%. The exact value is printed on the data sheet accompanying the product. Purity is assessed by HPLC, mass spectroscopy and/or amino acid analysis, with details of these available on request.

How do I dissolve peptides?

Most peptides are soluble in distilled water. If they do not completely dissolve, the addition of 1.0 M acetic acid for basic peptides (those containing Arg, Lys, His) or 1.0 M ammonium hydroxide for acidic peptides (those containing Asp, Glu) may help. Solubilisation of extremely insoluble peptides can be assisted with 10% DMSO or DMF although the use of these may interfere with some biological assays. Sonication can also be a useful aid for solubilising peptides.

How do I find peptides in the Tocris Bioscience catalogue?

Peptides are grouped in alphabetical order according to the root peptide; derivatives of this are then listed below (example 1). Prefixes are ignored (example 2).

Example 1:	In the ‘N’ section of the alphabetical listing in the catalogue: Nociceptin (catalogue number 0910) Nociceptin (1-7) (catalogue number 1266) [Nphe1]Nociceptin(1-13)NH2 (catalogue number 1308) [Phe1Ψ(CH2-NH)Gly2]Nociceptin(1-13)NH2 (catalogue number 1092)
Example 2:	In the ‘R’ section of the alphabetical listing in the catalogue: Ac-RYYRIKNH2 (catalogue number 1239)