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Systematic Underutilization of Glutamine In Thermophile ProteinsRapid racemization above 100 C of L-amino acids to Domino acids, as well as deamidation, is probably a hazard for high temperature life. For example, the half-life of some asparaginyl peptides can be as short as 10 minutes at 100 C. High temperature organisms could protect themselves by reducing usage of amino acids that are easily racemized/deamidazed, by having a rapid rate of protein turnover which requires energy, or by adapting special cis-peptide conformations. We have searched eight completely sequenced thermophile genomes, and compare them to mesophile genomes, in order to identify underutilized amino acids. To our surprise, asparagine, the most unstable amino acid to deamidation, is used at about the same level in thermophile proteins in comparison to mesophiles whereas it is the second most unstable amino acid, glutamine, that is underutilized in all of eight thermophile species. Glutamines are present at 2% level in a typical thermophile protein, instead of 4% in mesophile. We argue that it is easier to protect asparagines from deamidation by cis-peptide conformations. We discuss statistical as well as structural evidence in support of our conclusions.
Document ID
20020074617
Acquisition Source
Ames Research Center
Document Type
Preprint (Draft being sent to journal)
Authors
Liang, Shoudan
(NASA Ames Research Center Moffett Field, CA United States)
Weber, Arthur
(NASA Ames Research Center Moffett Field, CA United States)
Biegel, Bryan A.
Date Acquired
August 20, 2013
Publication Date
January 1, 2002
Subject Category
Inorganic, Organic And Physical Chemistry
Meeting Information
Meeting: Genome Informatics
Location: Cambridge
Country: United Kingdom
Start Date: September 4, 2002
End Date: September 8, 2002
Funding Number(s)
PROJECT: RTOP 755-30-11
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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