- Five- and six-membered ring opening of pyroglutamic diketopiperazine
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A variety of ring-opening reactions of pyroglutamic diketopiperazine at both the five-membered and six-membered rings is described. Mild, basic conditions facilitate nucleophilic attack by amines at the diketopiperazine carbonyls giving pyroglutamides in excellent yield. Reaction with nucleophiles under acidic conditions give bis-glutamate derivatives of 2,5-diketopiperazine (DKP). These reactions provide simple, two-step sequences to pyroglutamides and symmetrical diketopiperazines from commercial pyroglutamic acid with control of product dictated by reaction conditions, catalyst, and nucleophile.
- Parrish, Dennis A.,Mathias, Lon J.
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p. 1820 - 1826
(2007/10/03)
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- APPLICABILITY OF GLUTAMINYL-tRNA CYCLOTRANSFERASE IN THE PEPTIDE SYNTHESIS
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Peptides with amino-terminal glutamine and their derivatives on treatment with crude papain preparation, containing glutaminyl-tRNA cyclotransferase (E.C. 2.3.2.5.), are converted into the corresponding compounds with pyroglutamic acid.This enzymic cyclization does not take place with glutamic acid or its γ-derivatives.The reaction has been optimized for the preparation of pyroglutamic acid phenylhydrazide.Glutaminyl-leucine phenylhydrazide and glutaminyl-histidyl-proline amide reacted to give pyroglutamyl-leucine phenylhydrazide and TRH, respectively.Treatment of crude papain with iodoacetamide completely inhibited its activity without affecting the glutaminyl-cyclotransferase activity.
- Cerovsky, Vaclav,Jost, Karel
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p. 2310 - 2318
(2007/10/02)
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