How to choose the right resin functionality for solid phase peptide synthesis

As a chemist new to the peptide community, there are many choices that have to be made.  Which coupling reagents to use? Heat or no heat to promote chemistry? And most importantly, which resin?  I have talked previously about resin choices, from loading levels to swelling capacity and how they affect the synthesis outcome.  But I haven’t addressed yet a fundamental feature of commercially available resins, and that’s the functional handle to which the peptide chain is conjugated.

In today’s post, I’ll describe some, and I mean only some, of the most commonly used chemical functionalities for Fmoc-based solid phase peptide synthesis and some scenarios in which you would choose one resin type over another.

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Preventing aspartimide rearrangements during Fmoc-based solid phase peptide synthesis

Aspartimide rearrangements are a particularly nasty side reaction that can occur during fmoc-based solid phase peptide synthesis.  Not only is this a mass-neutral side reaction, chromatographically resolving the undesired, rearranged product can be particularly difficult.  To make matters worse, this side reaction can occur at any point during the synthesis after the Asp has been incorporated into the peptide.

In a prevous post, I described method that I have found useful for identifying whether or not an aspartimide rearrangment as occured during synthesis of a peptide that contains an aspartimide-susceptible sequence.  In today’s post, I’ll discuss some strategies that can be used to suppress, or even eliminate this side reaction. Continue reading Preventing aspartimide rearrangements during Fmoc-based solid phase peptide synthesis