Product FAQ's
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PRODUCT FAQs

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Product use and safety

Product purity and quality

Product appearance

Product technical information

Solubilisation

Storage and stability

Pack sizes and weighing accuracy

Peptides:

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What should the products be used for, and who should use them?

All products in our range are potentially hazardous and are strictly for laboratory research and development use only. They should not be used for pharmaceutical, veterinary, household, agricultural, food, cosmetic or any other human use. They should only be used by scientifically qualified personnel, trained in laboratory procedures.

Material Safety Datasheets are supplied with all of our products and contain advice regarding the safe handling of your product. However, due to the novel nature of our products, the potential hazards are not always known. It is therefore your responsibility to ensure that all relevant safety precautions are taken at all times.

What dose of antagonist, agonist or signalling tool should be used in vivo?

This is complex and depends on a number of factors including the method of administration (intravenous, intramuscular, or intraperitoneal), bioavailability, half-life, rates of hepatic and renal clearance, binding to proteins, drug interactions and tissue-specific distribution and accumulation. As we do not carry out any biological studies of our products in vivo, we therefore recommend that you review the published literature for dosage guidelines.

What dose of an antagonist, agonist or signalling tool should be used in vitro?

The amount of product required depends on many factors including target accessibility, cell permeability, duration of incubation, and type of cells or assay used, It is best to survey the literature to determine the IC50, EC50 or Ki. For an inhibitor, if published Ki or, IC50 values are known, we recommend that you use 5 to 10 times higher than these values to maximally inhibit enzyme or receptor activity. If there are no published values we recommend that you perform dose-response experiments (running appropriate controls) and use Michaelis-Menten kinetics to determine the Ki value.

How do I determine if a compound is cell-permeable?

There is no easy way of predicting if a product will be cell permeable. Generally charged molecules are not cell-permeable. However, modified phosphorylated compounds, such as mono- and dibutyryl cAMP, are cell-permeable. High molecular weight peptides are generally not cell-permeable under normal conditions.

Product purity and quality: what is it and how is it determined?

Our biochemicals are of very high purity, typically >98%. Chemical purity and quality are determined using a comprehensive range of techniques, including HPLC, chiral HPLC, NMR, microanalysis, optical rotation, TLC, and mass spectrometry. Details are provided on the Certificate of Analysis that accompanies each product.

What should I do if I can't see any product in the vial?

Products sold in small quantities may not be readily visible, as they can coat the bottom or walls of the vial. It is therefore important that you ensure that solvent comes into contact with all areas of the vial when solubilising your product.

Should different batches of a product look the same?

It is not unusual for different batches of the same product to vary slightly in appearance and colour. However, this will not affect purity or quality as described on the batch specific Certificate of Analysis and will not affect product performance.

Molecular weight and molecular formula

The molecular weight and formula published on our website represent the molecular weight and formula of the product as depicted in the chemical structure displayed on our website. However, molecular weights (and formulae) can vary slightly from batch to batch - due to water composition, or due to a change of salt. These changes will be indicated on the Certificate of Analysis that accompanies your product. The changes should not affect the biological activity of your product, but it is important that you take them into account when making up solutions. You should therefore always use the batch molecular weight as stated on the Certificate of Analysis or the vial label.

CAS registry numbers

To help you more easily identify a chemical, we provide CAS registry numbers for our products. CAS registry numbers are unique numerical identifiers for chemical substances. The Chemical Abstracts Service (CAS), a division of the American Chemical Society, assigns these identifiers to every chemical that has been described in the literature. Please note, that whilst these are given as accurately as possible on our website, they may not always reflect the level of hydration or salt of the product supplied.

Biological Activity

To assist you in your product selection, we provide a brief summary of the biological properties of our products, together with some suggested reading (references) that you may find useful. Please note, that whilst this information is given as accurately as possible on our website, it may not always reflect the latest findings and is not exhaustive. It is intended as a guide only and we therefore recommend that you carry out your own search of the scientific literature for full details of the product's biological activity.

Citations

We are often asked for examples of publications which cite Ascent Scientific products. We try to provide examples of these with our product data wherever possible. If you or your colleagues publish a paper which cites Ascent Scientific as the source of one or more of your materials, please send us the details - and we will send you a free gift!

How do I dissolve my product?

Solubilisation instructions can be found on the Product Data Sheet accompanying your product, or on the website. Some products may be difficult to solubilise, and you may find that rapid stirring, warming in a water bath, or sonication of the solution may help.

Solubility is temperature dependent. As such, cooling or freezing solutions may lead to precipitation of the product out of solution. It is therefore important to ensure that your product is completely re-dissolved before use.

Dissolving amino acids: how do I make solutions using NaOH equivalents?

Amino acids are often difficult to solubilise. A common technique is to use 1 molar equivalent (1eq) of sodium hydroxide (NaOH).

To dissolve compound in 1 equivalent of NaOH(aq.), the following formula can be used to calculate the volume of NaOH (aq) (VolNaOH) of concentration (ConcNaOH ) needed

Mass compound (mg)x 1000

    = VolNaOH(mL)

197.130 x ConcNaOH (mM)

e.g for a product with a molecular weight of 197.13g, a mass of 5 mg, and using 100 mM NaOH:

5 x 1000

    = 0.254 ml of NaOH

197.13 x 100NaOH (mM)

How should I store my product?

We carry out regular stability tests of our products. However, due to the novel nature of many of our biochemicals, there is little published information on long-term product stability.

You should always follow the recommendations stated on the Product Data Sheet. However, we offer the following as a general guide:

Solid: Provided storage is as stated on the product vial and the vial is kept tightly sealed, the product can be stored for up to 6 months.

Solution: Wherever possible, you should prepare and use solutions on the same day. However, if you need to make up stock solutions in advance, we recommend that you store the solution as aliquots in tightly sealed vials at -20°C. Generally, these will be useable for up to one month. Before use, and prior to opening the vial we recommend that you allow your product to equilibrate to room temperature for at least 1 hour.

Effects of storage on solubility

Solubility is temperature dependent. As such, cooling or freezing solutions may lead to precipitation of the product from solution. It is therefore important to ensure that your product is completely re-dissolved before use.

Why does Ascent Scientific sometimes ship chemicals at room temperature when the vial is labelled 'store at +4oC or -20oC'?

Storage in the refrigerator or freezer is often recommended for long-term stability of a product. If the product is shipped at ambient temperature it is considered to be stable for the duration of shipping and normal handling. Upon receipt you should then store it in the refrigerator or freezer (as indicated on the label). If you have any specific shipping requirements, please contact customer service.

Pack sizes and weighing accuracy: do I need to reweigh my product?

Unless explicitly stated on the Product Data Sheet, the quantity of material supplied in our vials is not weighed to the accuracy required for direct solution preparation.

How much peptide is in my vial?

Ascent Scientific peptides are supplied either by net peptide weight, or gross weight and this will be indicated on the Certificate of Analysis accompanying the product.

While peptides for research use are typically > 95% pure by HPLC, the peptide content of the solid may typically range from 70 to 90% as peptides contain counter ions (e.g. acetate, trifluoroacetate) and residual moisture. The peptide content of each batch is shown on the Certificate of Analysis that accompanies each product.

Net peptide weight: For those peptides supplied by net peptide weight, these are weighed so that the amount of peptide received is exactly that stated on the vial. The actual amount of solid present in the vial will be dependent on the peptide content.

Gross weight: For those peptides supplied by gross weight, it is important that peptide content is taken into consideration.The peptide content is determined by amino acid analysis and is typically 70-90%. The net peptide weight is calculated by multiplying the peptide content by the gross weight. For example, a sample of peptide with gross weight of 5 mg and peptide content of 85% has a net peptide weight of 4.25 mg (5 mg x 0.85).

How should I handle lyophilized peptides?

  • Peptides should be stored at -20°C for maximum stability. They should not be stored in frost-free freezers as variations in moisture and temperature may affect product stability.
  • Because peptides are often hygroscopic, they can absorb water, which may decrease stability and reduce the overall peptide content. To minimize this, allow peptide samples to equilibrate to room temperature in a desiccator for at least 1 hour prior to opening the vial and weighing the peptides.
  • Weigh out peptides quickly and reseal bottle tightly.

How should I solubilise and store peptides?

Dissolve peptides in an appropriate buffer: acidic peptides in basic buffer and basic peptides in acidic buffer. If necessary, sonicate briefly.

  • Peptides containing Trp, Met or Cys require special care to avoid oxidation. Oxygen-free water or reducing agents may be used.
  • For storage, peptide solutions should be aliquoted and kept frozen at -20°C. Most peptides containing Trp, Met, Cys, Asn or Gln have limited shelf life. Long-term storage is not recommended.
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"… the timing was perfect. I would like to compliment you on the documentation that you provided… We feel very confident in the purity of our compound."

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