The Racemization Rate Constant for Protein-Bound Aspartic Acid in Woodrat Middens

Petit, M.

doi:10.1016/0033-5894(74)90020-9

Cited by 12 publications

(5 citation statements)

References 16 publications

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“…Racemization rates depend greatly upon temperature and the R-group of the amino acid, and are additionally influenced (but much less strongly) by pH and by ill-defined "local environmental effects" within the polypeptide (14). Content of D-amino acids in proteins has been correlated with the age of various archaeologic and paleontologic specimens (25)(26)(27)(28)(29)(30)(31)(32)(33). Racemization of aspartic acid occurs rapidly relative to that of the other amino acids.…”

Section: Introductionmentioning

confidence: 99%

Marked longevity of human lung parenchymal elastic fibers deduced from prevalence of D-aspartate and nuclear weapons-related radiocarbon.

Shapiro

Endicott²,

Province³

et al. 1991

J. Clin. Invest.

551

367

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Normal structure and function of the lung parenchyma depend upon elastic fibers. Amorphous elastin is biochemically stable in vitro, and may provide a metabolically stable structural framework for the lung parenchyma. To test the metabolic stability of elastin in the normal human lung parenchyma, we have (a) estimated the time elapsed since the synthesis of the protein through measurement of aspartic acid racemization and (b) modeled the elastin turnover through'measurement ofthe prevalence of nuclear weapons-related "C. Elastin purified by a new technique from normal lung parenchyma was hydrolyzed; then the prevalences of D-aspartate and "4C were measured by gas chromatography and accelerator-mass spectrometry, respectively. D-aspartate increased linearly with age; K,,.,p (1.76x 10-3yr-') was similar to that previously found for extraordinarily stable human tissues, indicating that the age of lung parenchymal elastin corresponded with the age of the subject. Radiocarbon prevalence data also were consistent with extraordinary metabolic stability of elastin; the calculated mean carbon residence time in elastin was 74 yr (95% confidence limits, 40-174 yr). These results indicate that airspace enlargement characteristic of "aging lung" is not associated with appreciable new synthesis of lung parenchymal elastin. The present study provides the first tissue-specific evaluation of turnover of an extracellular matrix component in humans and underscores the potential importance of elastin for maintenance of normal lung structure. Most importantly, the present work provides a foundation for strategies to directly evaluate extracellular matrix injury and repair in diseases of lung (especially pulmonary emphysema), vascular tissue, and skin. (J. Clin. Invest. 1991.

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Section: Introductionmentioning

confidence: 99%

Marked longevity of human lung parenchymal elastic fibers deduced from prevalence of D-aspartate and nuclear weapons-related radiocarbon.

Shapiro

Endicott²,

Province³

et al. 1991

J. Clin. Invest.

551

367

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“…(For amino acids with more than one asymmetric center, the ratio is different from 1.0, i.e., the ratio alloisoleucine/isoleucine equals approximately 1.3. )The extent of racemization of amino acids may be used to estimate the ages of various fossil materials, including deepsea sediments (5-7), shells (8-11), fossil bones (2-4, 12-15), and coprolites (16). Of the various amino-acid racemization reactions, the one involving aspartic acid has received the most attention.…”

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confidence: 99%

“…The extent of racemization of amino acids may be used to estimate the ages of various fossil materials, including deepsea sediments (5)(6)(7), shells (8)(9)(10)(11), fossil bones (2)(3)(4)(12)(13)(14)(15), and coprolites (16). Of the various amino-acid racemization reactions, the one involving aspartic acid has received the most attention.…”

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confidence: 99%

Aspartic acid racemization in tooth enamel from living humans.

Helfman¹,

Bada²

1975

Proc. Natl. Acad. Sci. U.S.A.

259

140

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The aspartic acid in human tooth enamel shows increasing racemization with age. This increase is not seen in the metabolically active protein hemoglobin. The rate constant for the racemization reaction of aspartic acid in human tooth enamel was found to be 8.29 X 10-4 yr-1. This rate constant suggests that in any protein with a long in vivo lifetime, D-aspartic acid will accumulate with age (about 8% of total aspartic acid in enamel will be the D-enantiomer after 60 years). Thus, racemization may play some role in the aging process affecting metabolically stable tissues in long-lived homeotherms. Aspartic acid racemization in tooth enamel also provides a biochronological tool for assessing the age of living mammals.Racemization is a natural process which will eventually-convert optically active compounds into a racemic mixture. The L-amino acids commonly found in living systems are the result of the stereochemical specificity of enzymes which utilize only the L-enantiomers. Racemization of amino acids in the proteins produced by living organisms would thus take place only after protein turnover has ceased. Recent studies (1-4) have shown that at 25°a period of about 100,000 years is required before all the L-amino acids present in living systems will have undergone complete racemization to an equilibrium mixture in which the ratio of D-to L-amino acids equals 1.0. (For amino acids with more than one asymmetric center, the ratio is different from 1.0, i.e., the ratio alloisoleucine/isoleucine equals approximately 1.3.)The extent of racemization of amino acids may be used to estimate the ages of various fossil materials, including deepsea sediments (5-7), shells (8-11), fossil bones (2-4, 12-15), and coprolites (16). Of the various amino-acid racemization reactions, the one involving aspartic acid has received the most attention. This amino acid has one of the fastest racemization rates of the stable amino acids (1). In bone, the half-life of aspartic acid racemization (the time required for the ratio of D-to L-enantiomers to reach 0.333) is about 15,000 years at 200 (3,15). Thus, for temperate to nearequatorial environments, significant racemization of aspartic acid will have taken place in a bone during the last 40,000 years (the upper limit of radiocarbon dating).The temperature dependence of the rate of the aminoacid racemization reaction can also be used to estimate the temperature history of a sample of known age. By determining the extent of aspartic acid racemization in a radiocarbon-dated bone, it is possible to calculate the in situ rate of racemization, and this rate constant can then be used to estimate the average temperature to which the bone has been exposed (17). Racemization analysis of -radiocarbon-dated bones with ages less than about 12,000 years (i.e., post-glacial) have yielded rate constants which are proportional to the present-day average annual air temperatures of the sites where the bones were found (15).Based on the correlations between aspartic acid racemiza-2891 METHODS Teeth ...

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“…Original methods of analysis Initial methods used stereospecific enzymes to preferentially destroy one chiral form (Hare and Abelson, 1968;Petit, 1974), but the most robust technique is separation using chromatography, either by gas (GC) or liquid (LC). GC allows the determination of the D-and L-forms of several amino acids, but has been less commonly used due to the more complicated preparation methods.…”

Section: Introductionmentioning

confidence: 99%

Amino acid geochronology: its impact on our understanding of the Quaternary stratigraphy of the British Isles

Penkman

2009

J Quaternary Science

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This review aims to act as a brief primer to amino acid racemization and protein breakdown, as well as to document the major applications and results of amino acid dating on British Quaternary sediments. Amino acid results from fossil shells have had far-reaching effects in developing our current understanding of British Quaternary stratigraphy and its links to continental Europe and the marine record. To appreciate the potential for amino acid geochronology, the technique's limitations and recent developments are discussed, as well as the future of the field.

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The Racemization Rate Constant for Protein-Bound Aspartic Acid in Woodrat Middens

Cited by 12 publications

References 16 publications

Marked longevity of human lung parenchymal elastic fibers deduced from prevalence of D-aspartate and nuclear weapons-related radiocarbon.

Marked longevity of human lung parenchymal elastic fibers deduced from prevalence of D-aspartate and nuclear weapons-related radiocarbon.

Aspartic acid racemization in tooth enamel from living humans.

Amino acid geochronology: its impact on our understanding of the Quaternary stratigraphy of the British Isles

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