Considerations on the Role of Aspartic Acid Racemization in the Aging Process

Helfman, Patricia Masters; Bada, Jeffrey L.; Shou, Ming-Yung

doi:10.1159/000212218

Cited by 63 publications

(40 citation statements)

References 5 publications

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“…In addition, there were many studies the relationship between extent of amino acid racemization and age in human teeth (Ohtani 1995b;Shimoyama & Harada 1984). They found high correlation of racemization and age that was consistent with results of another study by Helfman et al (1977). This suggested that amino acid racemization can be utilized for age estimation.…”

Section: History Of Age Estimation By Using Aspartic Acid Racemizationsupporting

confidence: 74%

“…They reported a relationship between concentration of D-aspartic acid and age in these tissues and particularly in dentine which is better correlate than enamel (r=0.979). The previous study (Helfman et al 1977) reported that aspartic acid racemization is a process which occurs in metabolically stable proteins of the mammalian body and amino acid within protein and are changed with increasing age. In addition, there were many studies the relationship between extent of amino acid racemization and age in human teeth (Ohtani 1995b;Shimoyama & Harada 1984).…”

Section: History Of Age Estimation By Using Aspartic Acid Racemizationmentioning

confidence: 99%

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Age Estimation by Using Aspartic Acid Racemization from Purified Elastin of Aorta

Komutrattananont¹,

Mahakkanukrauh²

2017

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ABSTRAK ABSTRACTAge estimation is the one of biological profiles which plays an important role in identification in forensic field. The application of biochemical approach known 171 Age Estimation by Aspartic Acid Racemization Med & Health Dec 2017;12(2): 170-178 depend on the variation methods and skill of the specialist (Dobberstein et al. 2010). However, there are still high accuracy methods in age estimation which complicate the procedure more. One of these methods which has been accomplished in age estimation is amino acid racemization. AMINO ACID RACEMIZATIONAmino acids are vital components in living organisms and are subunit structure of all proteins. The amino acid structure is composed of a carbon atom (C) which has four different groups include an amino group (-NH 2 ), a carboxyl group (-COOH), a hydrogen atom (-H), and side chain or Rgroup (-R). Side chain is different part of amino acids that depends upon the kind of as aspartic acid racemization in human provides more accuracy and less error of estimated age in age determination. During aging, amino acids within protein transform between D-and L-form (racemization), which results in increasing concentration of D-amino acids. This change of amino acids is related to aging. Aspartic acid has been generally applied in racemization because it has fastest rate of racemization. Racemization of aspartic acid not only takes place in teeth and many kinds of bone, but also can occur in the flexible structure which contain mostly elastin. For example, skin yellow ligament, lung parenchyma, and aorta. Elastin is essential protein which is comprised most composition of several structures and it is major content in the elastic fibers. Additionally, elastin is the longest lasting protein in the body with slow metabolic turnover rate. Recently, there is a purification technique to obtain only single protein in human aorta.There was a good correlation between degree of racemization (D/L ratio) and age. Therefore, aspartic acid racemization by purifies elastin from aorta is a one of indicator for age estimation. This review provides an overview of aspartic acid racemization, elastin protein, purification method bases on racemization and the application of D/L ratio by purified of elastin in artery for age estimation.

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Section: History Of Age Estimation By Using Aspartic Acid Racemizationsupporting

confidence: 74%

Section: History Of Age Estimation By Using Aspartic Acid Racemizationmentioning

confidence: 99%

Age Estimation by Using Aspartic Acid Racemization from Purified Elastin of Aorta

Komutrattananont¹,

Mahakkanukrauh²

2017

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“…1B) and the nucleus (Fig. 1C) with the prediction that racemization of aspartyl residues would induce conformational changes in a protein, and these in turn could alter its physicochemical properties (9). Because HMW aggregates are thought to be precursors to the WI protein, the high D/L Asp ratio in the HMW fraction (Table 3) suggests that racemization precedes the formation of WI protein.…”

Section: Discussionmentioning

confidence: 83%

“…We have previously suggested that alterations in protein conformation will result from racemization of aspartyl residues (9). If racemization is to any degree responsible for the changes in the properties of lens proteins, then D-aspartic acid should…”

mentioning

confidence: 99%

Aspartic acid racemization in heavy molecular weight crystallins and water insoluble protein from normal human lenses and cataracts.

Masters¹,

Bada²,

Zigler³

1978

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

117

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High D/L aspartic acid ratios are observed in heavy molecular weight aggregates and in water-insoluble protein extracted from whole lenses and nuclear and cortical regions. Purified a-, A-, and -y-crystallins have low D/L ratios. Fractionation of urea-solubilized material from the water-insoluble protein yields four molecular weight classes of proteins. Fractions representing crosslinked material or apparently degraded products have high D/L ratios. Racemization within lens proteins may contribute to formation of the water-insoluble fraction seen in aging lenses and cataracts. The racemization of aspartyl residues has recently been added to the list of age-related changes taking place in the proteins of the human lens (1). D-Aspartyl residues have been shown to accumulate at the rate of 1.25 X 10-3 yr-1 or 0.14% yr-1 in the central nucleus. The extent of racemization in yellow cataracts is equivalent to that observed in age-matched normal lenses, but brunescent cataracts exhibit up to a 2-fold increase in D/L aspartic acid ratios over comparably aged normal lenses or yellow cataracts.The rationale for investigating lens proteins came from our studies of calcified proteins in human teeth (2, 3). Detectable amounts of D-aspartic acid accumulate during the human lifespan as a result of the spontaneous chemical racemization reaction. These findings suggested that the aspartyl residues in any metabolically stable protein maintained at mammalian body temperature for several decades or longer would be subject to racemization. Because the proteins in the nucleus of the human lens are among the most stable in the body, we decided to test our hypothesis with the lens system.Numerous studies have shown that structural changes are taking place in lens proteins during the normal aging process and in cataracts. The proportion of water-insoluble protein increases relative to water-soluble protein (4, 5). The increase of insoluble protein is more marked in cataracts (6). When the water-insoluble residue is extracted with 7 M urea, the ureainsoluble portion is greater in cataracts (6) and is derived primarily from the lens nucleus (7). There is some evidence that more exposed thiol groups occur in cataractous proteins, and these proteins may have a greater susceptibility to tryptic digestion (8). All of these observations indicate that changes in native conformation of the lens proteins are occurring in cataract development and in aging.We have previously suggested that alterations in protein conformation will result from racemization of aspartyl residues (9). If racemization is to any degree responsible for the changes in the properties of lens proteins, then D-aspartic acid should

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“…Consequently, amino acid racemization is widely applied for age estimation in many tissues which comprise proteins. Furthermore, the relationship between amino acids racemization and age can be used for investigation of lifetime of protein ageing (Helfman et al 1977) and pathological diseases in older individuals (Powell et al 1992;Shapiro et al 1991). …”

Section: Amino Acid Racemizationmentioning

confidence: 99%