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Synthetic Methods
Psyche uses a new type of solution synthesis that yields homogeneous protected protein fragments.1 Mass spectroscopy is routinely used to guarantee that acylation reactions are more than 99.9% complete.2 The protected fragments are characterized by HPLC, amino acid analysis and LC/MS after which they are joined and deprotected to yield the product. LC/MS on a C-18 column with a water:CH3CN gradient (0.2% TfaOH) is used to measure homogeneity.
- Head DB, Dong JZ, et al. (2005). ?Use of the excluded protecting group (EPG) method for peptide synthesis.? Peptide Sci 65, 384-94.
- Burton JA, Hancock, W, et al. (2006) Use of electrospray mass spectroscopy to quantitate acylation reactions in the EPG method of peptide synthesis. J Am Chem Soc (submitted)
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Protecting Groups
Psyche Peptides, Inc. is staffed by expert chemists familiar with most protecting groups, coupling methods, etc. For manufacture the Fmoc/t-butyl strategy is generally used. Side chain protecting groups include: Cys (Trt, Acm), His(Boc, Fmoc), Asn (Trt, none), Gln (Trt, none), Arg (Pbf, Pmc) and Trp (Boc, none). Fragment couplings are normally done with TBTU.
On completion of a synthesis the cysteine protecting group is removed and the appropriate disulfide bonds formed. When the disulfide bonds do not form naturally, the product is sent to the customer with scrambled disulfides. Alternatively, the protein with the protected cysteine residues will be sent to the customer along with detailed instructions on removal.
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All of Psyche's methods are protected by US patents.
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