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PolyAmino Acids: Production Methods FAQ

  1. What is the general method of polymerization?
  2. What are the solvents used for polymerization?
  3. What protecting groups are used in polyamino acids?
  4. How are protecting groups removed from the protected polymer?
  5. For succinylated polylysine (Catalog No. P3513), is the succinyl group located on the ε (epsilon) amino or on the terminal amine (or carboxyl group)?
  6. How are the polyamino acids purified?
  7. Can Sigma-Aldrich use ultra filtration for polyamino acid polymer purification?
  8. Can Sigma-Aldrich produce exactly the same molecular weight polyamino acids from lot to lot?
  9. Are the starting materials for polyamino acids synthetic or of natural (plant or animal) origin?
  10. What was the reason for changing all raw materials for polyamino acids to non-animal source?
  11. How long has Sigma-Aldrich been making polyamino acids?

What is the general method of polymerization?
In most cases, the starting monomer is the NCA (N-Carboxyanhydride) derivative of an amino acid, with any reactive side chain groups protected. Polymerization is initiated with base, followed by removal of any protecting groups.

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What are the solvents used for polymerization?
In general, the organic solvents used for polymerization are acetonitrile, methylene chloride, chloroform, 1,4-dioxane, etc. Product specific information is proprietary.

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What protecting groups are used in polyamino acids?
In general, the carbobenzyloxy (Z) group is used to protect the side chain amino groups, and the Benzyl (Bzl) group is used to protect the side chain carboxyl groups. For amino acids which contain a hydroxyl side chain, the hydroxyl groups are protected by using the Z group for tyrosine (Tyr), either the Z or Acetyl (Ac) groups for Serine (Ser), and the Trichloroethyl group for Threonine (Thr).

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How are protecting groups removed from the protected polymer?
The protecting groups are removed by treating the protected polymer with a strong inorganic acid. The actual identity of the acid is proprietary.

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For succinylated polylysine (Catalog No. P3513), is the succinyl group located on the ε (epsilon) amino or on the terminal amine (or carboxyl group)?
The succinyl group is on the epsilon amino group of the side chain.

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How are the polyamino acids purified?
Dialysis is typically used for purification of water-soluble polyamino acids. Washing with an organic solvent is used to purify water-insoluble polyamino acids.

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Can Sigma-Aldrich use ultra filtration for polyamino acid polymer purification?
Yes. We have developed an ultra filtration method for purification of cGMP-prepared polyamino acids and have transferred the method to selected non-cGMP polyamino acids as well.

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Can Sigma-Aldrich produce exactly the same molecular weight polyamino acids from lot to lot?
No. As with any synthetic polymerization method, there is always lot-to-lot variation in molecular weight range. However, Sigma-Aldrich and the customer can set an acceptable molecular weight range and develop a process that gives lot-to-lot reproducibility within the range.

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Are the starting materials for polyamino acids synthetic or of natural (plant or animal) origin?
All polyamino acids produced after 2001 are manufactured using amino acids from non-animal sources (either synthetic or by fermentation of plant origin material). For each raw material amino acid, the vendor’s Certificate of Origin is screened upon receipt of the material before production begins. The vendor’s certificate of origin is kept on file for future reference.

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What was the reason for changing all raw materials for polyamino acids to non-animal source?
Sigma-Aldrich noticed that many customers were beginning to use polyamino acids for drug delivery applications because the unique nature and size of amino acid polymers mimics those of proteins. To help customers avoid animal source issues, in 2001 Sigma-Aldrich changed all polyamino acid production to require non-animal source raw materials.

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How long has Sigma-Aldrich been making polyamino acids?
Sigma-Aldrich has been making polyamino acids since 1980 and has developed a vast wealth of knowledge, expertise, and experience.

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