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Determination of the Gas-phase Acidities of Oligopeptides
Published on: June 24, 2013
THE ACTION OF ALKALIES ON PEPTIDES AND ON KETOPIPERAZINES.
1Laboratories of The Rockefeller Institute for Medical Research.
The Journal of General Physiology
|October 30, 2009
Summary
Peptides like glycyl-levo-alanyl-glycine and levo-alanyl-glycine are stable against racemization in alkaline solutions. However, ketopiperazines, such as levo-alanyl-glycine anhydride, undergo partial racemization influenced by alkali concentration and ring stability.
Area of Science:
- Peptide chemistry
- Organic chemistry
- Biochemistry
Background:
- Racemization, the loss of optical activity in chiral molecules, is a critical factor in peptide and protein stability.
- Understanding racemization mechanisms is essential for fields ranging from drug development to food science.
Purpose of the Study:
- To investigate the susceptibility of specific peptides and their corresponding ketopiperazines to racemization under alkaline conditions.
- To determine the factors influencing the extent of racemization in these compounds.
Main Methods:
- Treatment of the tripeptide glycyl-levo-alanyl-glycine and the dipeptide levo-alanyl-glycine with varying concentrations of alkali.
- Treatment of levo-alanyl-glycine anhydride and levo-prolyl-glycine anhydride with dilute alkali.
- Observation and quantification of racemization using methods not explicitly detailed but implied by the context of chirality studies.
Main Results:
- The tripeptide glycyl-levo-alanyl-glycine and the dipeptide levo-alanyl-glycine showed no racemization when exposed to alkaline solutions.
- Ketopiperazines, specifically levo-alanyl-glycine anhydride and levo-prolyl-glycine anhydride, exhibited partial racemization in the presence of dilute alkali.
- The degree of racemization was found to be incomplete and dependent on both the stability of the ketopiperazine ring and the alkali concentration.
Conclusions:
- Linear peptides are resistant to racemization under the tested alkaline conditions.
- The cyclic structure of ketopiperazines renders them susceptible to alkali-induced racemization.
- Further studies on a broader range of polypeptides and ketopiperazines are needed to fully elucidate these racemization phenomena.
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