A critical evaluation of the application of amino acid racemization to geochronology and geothermometry

Williams, Katie; Smith, Grant Gill

doi:10.1007/bf00927978

Cited by 131 publications

(46 citation statements)

References 119 publications

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“…However, in some cases [2][3][4][5] ,racemization has been used to meanboth racemization and epimerization. Epimerization and racemization in amino acids, peptides, and proteinshave been investigated from many viewpoints [2][3][4][5][6][7][8][9][10][11] . Epimerization of aspartic residues in proteins may sometimes increase thehydrophobicity of the proteins, because several diastereomeric peptides composed of D-aspartic residues show higher hydrophobicity than the…”

Section: E P I M E R I Z a T I O N R E A C T I O N S P R O D U C E Dimentioning

confidence: 99%

“…Ionic mechanisms of racemization and epimerizationwere proposed by G. G. Smithand co-workers 6,[12][13][14][15][16][17][18][19][20] , whoshowed that the rates of racemization of peptides were faster than those of free amino acids. However, this research wasmainly restricted to the epimerization of linear peptides and the racemization of 2,5-diketopiperazines bearing one chiral center, and did not consider cyclic diastereomeric peptides.…”

Section: Oriental Journal Of Chemistrymentioning

confidence: 99%

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Epimerization of Cyclic Alanyl-Alanine in Basic Solutions

Munegumia¹,

Fujimoto²,

MichioTakada³

et al. 2014

Orient. J. Chem

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Alanine anhydrides (Cyclo-(Ala-Ala)) are the simplest dipeptides that have two chiral centers and three diastereomers: Cyclo-(L-Ala-L-Ala), Cyclo-(D-Ala-D-Ala), and Cyclo-(L-Ala-D-Ala).Analysis of the epimerization of these peptides may throw light on the development of homochirality in proteins. We show that the epimerization rate of Cyclo-(L-Ala-L-Ala) and Cyclo-(D-Ala-D-Ala) is higher than that of Cyclo-(L-Ala-D-Ala), while the ring-opening rates of Cyclo-(L-Ala-L-Ala) and Cyclo-(D-Ala-DAla) arelower than that of Cyclo-(L-Ala-D-Ala) in basic aqueous solutions. The total reaction resulted in the preferred stability of Cyclo-(L-Ala-L-Ala) and Cyclo-(D-Ala-D-Ala) to Cyclo-(D-Ala-L-Ala).

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Section: E P I M E R I Z a T I O N R E A C T I O N S P R O D U C E Dimentioning

confidence: 99%

Section: Oriental Journal Of Chemistrymentioning

confidence: 99%

Epimerization of Cyclic Alanyl-Alanine in Basic Solutions

Munegumia¹,

Fujimoto²,

MichioTakada³

et al. 2014

Orient. J. Chem

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“…It was shown by Hare and Abelson (1) and then by others (2)(3)(4)(5) that the abundance of racemized amino acids (particularly aspartic acid) is a measure of the aging of biological material (6). Such a parameter may be used to examine precursor relationships in the development of cataract.…”

mentioning

confidence: 99%

Racemization in human lens: evidence of rapid insolubilization of specific polypeptides in cataract formation.

Garner¹,

Spector²

1978

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

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After early life, the dry weight of normal human lenses increases at a relatively constant rate with time.Transformation from soluble to insoluble material appears to occur at a comparable rate, resulting in a constant amount of soluble material. However, in cataract the insolubilization rate is accelerated. These observations are supported by determination of D-aspartic acid/L-aspartic acid ratios. The lens is composed primarily of protein which comprises most of the dry weight (7). It has been previously shown that the relative percentage of water-insoluble material increases with aging in both animal (8) and human (9-11) lenses and in the development of lens opacities (9)(10)(11) (14).The subunit polypeptides of 65-to 72-year-old cataractous lens protein were isolated from Sephadex G-150 and G-100 equilibrated with 10% HOAc and 7.2 M urea as described elsewhere (15). All polypeptides described were reduced and alkylated prior to their purification unless otherwise noted. RESULTS AND DISCUSSIONWhen the total dry weight (water-soluble plus water-insoluble) of normal lenses is plotted against age, after the first few years of rapid growth an increase in apparent weight of approximately 0.4 mg/yr is found (Fig. 1). Similar results have been observed by Klethi (17). Determination of the dry weight of the water-insoluble fraction suggests that it increases at the same rate as the total dry weight. Such observations indicate that the absolute amount of the water-soluble fraction remains constant at approximately 30 mg, and the rate of conversion of soluble to insoluble material is constant in the normal lens. Thus, the percentage of insoluble material increases at a constant rate from about 2% at birth to approximately 50% by about age 70 years.When individual cataractous lenses were examined (open circles in Fig. 1), the total weight generally corresponded (within experimental error) to that of normal lenses of the same age group. However, the amount of the water-insoluble fraction in the cataractous lenses (solid circles) was dramtically greater than in the normal lenses, suggesting a more rapid conversion of soluble to insoluble material. Thus, it would appear that a relatively rapid loss of water-soluble protein may be correlated with lens opacity.The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §1734 solely to indicate this fact.

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“…The uncertainty in age determination is thought to be primarily due to an unknown temperature history (25) but this work has shown that there is uncertainty in the chemistry as well. The utility of the method may lie in restricting the kinds of peptide units used for analysis, namely, the peptide units in the interior of the protein.…”

Section: Discussionmentioning

confidence: 97%

Model studies of competing hydrolysis and epimerization of some tetrapeptides of interest in amino acid racemization studies in geochronology

Moir¹,

Crawford²

1988

Can. J. Chem.

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The processes of epimerization of individual peptide units in proteins and the concurrent cleavage of peptide bonds are modelled by heating some tetrapeptide and tetrapeptide derivatives to 148S°C in pH 6.8 phosphate buffer. An excess of D-proline was observed during the heating of L-prolyl-L-leucylglycylglycine. The D/L ratio of proline attains a maximum value of 2.1 after 90 minutes. The excess D-proline is attributed to the formation of a 2.3:1 mixture of diketopiperazines ~y~l~-(D-pr~lyl-L-le~~yl) and cyclo-(L-prolyl-L-leucyl). These two species account for most of the leucine and proline in the final mixture after the tetrapeptide is no longer detectable. Only small amounts of prolylleucine can be detected after 50 hours. It is suggested that the above tetrapeptide undergoes internal aminolysis. Leucine in the tetrapeptide glycyl-L-leucylglycylglycine racemizes three times faster than in L-prolyl-L-leucylglycylglycine. This demonstrates that an amino acid residue in a peptide chain does have an effect upon the rate of epimerization of a neighbouring peptide residue. A discussion of the geochemical implications of the results is included. MICHAEL E. MOIR ET ROBERT J. CRAWFORD. Can. J. Chem. 66,2903Chem. 66, (1988.Afin de dtvelopper un modkle des processus d'tpimtrisation des unitts peptidiques de prottines et du clivage apparent6 des liaisons peptidiques, on a chaufft des tttrapeptides ainsi que leurs dtrivts 148,5"C, dans un tampon de phosphate, a un pH de 6,s. Lorsqu'on a chaufft le L-prolyl-L-leucylglycylglycine, on a observe la formation d'un excks de D-proline. Le rapport de D/L proline atteint une valeur maximale de 2,1 aprks 90 minutes. On attribue la formation d'un excbs de proli line a la formation d'un mtlange 2,3:1 des dicttopiptrazines cyclo-(D-prolyl-L-leucyl) et cyclo-(L-prolyl-L-leucyl). Ces deux espbces peuvent expliquer la formation de la plus grande partie de la leucine ainsi que de la proline prtsentes dans le mtlange final, mCme lorsqu'on ne peut plus dttecter la prtsence du tttrapeptide. On ne peut dttecter la prtsence que de faibles quantitts de prolylleucine aprks 50 heures. On suggkre que le tttrapeptide utilist subit une aminolyse interne. La leucine du tttrapeptide glycyl-L-leucylglycylglycine se ractmise trois fois plus rapidement que dans le L-prolyl-L-leucylglycylglycine. Ce rtsultat dtmontre que le rksidu d'acide amint d'une chaine peptidique influence la vitesse d'tpimtrisation du rtsidu voisin. On prtsente une discussion des implications gtochimiques de nos rksultats.[Traduit par la revue]

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A critical evaluation of the application of amino acid racemization to geochronology and geothermometry

Cited by 131 publications

References 119 publications

Epimerization of Cyclic Alanyl-Alanine in Basic Solutions

Epimerization of Cyclic Alanyl-Alanine in Basic Solutions

Racemization in human lens: evidence of rapid insolubilization of specific polypeptides in cataract formation.

Model studies of competing hydrolysis and epimerization of some tetrapeptides of interest in amino acid racemization studies in geochronology

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