Is there a correlation between age and D-aspartic acid in human knee cartilage?

Abstract

L-Aspartic acid (L-Asp) is one of the fastest racemizing amino acids such that the abnormal D-form (D-Asp) has been found in stable biological human tissues such as dentin in teeth, eye lens and brain. Earlier reports showed that there was a linear correlation between age and D-Asp in teeth. We have previously reported that significant levels of D-Asp were found in normal and osteoarthritic knee cartilage. Since cartilage is a slow regenerating tissue, we hypothesized that D-Asp should accumulate in knee cartilage and that there might be a correlation between the age of the person and the amount of D-Asp found in cartilage. Our analysis of approximately 100 samples of normal knee cartilage showed that there are detectable amounts of D-Asp (2-4% of total Asp) in knee cartilage. However, there was only a slight correlation (r = 0.35) between the age of the person and the amount of D-Asp (nmoles/g). Surprisingly, there was a better correlation between age and the amount of D-Asp in the male subjects (r = 0.57) than in the female subjects (r = 0.21).

Amino acid racemization reveals differential protein turnover in osteoarthritic articular and meniscal cartilages

“…The age-related accumulation of D -Asx we observed in normal articular cartilage ( D / D + L versus age, r 2 = 0.778) is consistent with previous reports [ 2 , 3 , 10 ] describing a strong association of D -Asp with age in normal articular cartilage ( r 2 = 0.903) and normal rib cartilage ( r 2 = 0.58 to 0.94) but stands in contrast to a recent report [ 16 ] showing very little association with age ( r 2 = 0.123) in normal articular cartilage. The results of this last study are perhaps not surprising given the fact that it evaluated only D -Asp versus age, instead of the ratio of either D / L or D / D + L , which are the accepted methods of comparison in the literature.…”

Estimation of Chronological Age from Postmortem Tissues Based on Amino Acid Racemization

“…According to the previous studies, the AAs in the samples are racemized at the hydrolysis stage and the racemization caused by the hydrolysis may also make the calculation of the actual rates difficult and requires the rate to be multiplied by a validation coefficient . The racemization is not only dependent on the factors like the temperature, the time, and the hydrolysis, but also on the amount of tissue used as well.…”

Role of D-aspartate on biosynthesis, racemization, and potential functions: A mini-review

“…Aspartate widely exists in animal tissues with D-enantiomers, especially in nervous and reproductive systems ( Ota et al, 2012 , Di Fiore et al, 2014 ). In 1977, high concentration of D-aspartate has been firstly found in the brain of Octopus vulgaris Lam ( D'Aniello and Giuditta, 1977 ) and D-aspartate in other tissues has been also detected subsequently, including heart, lung, stomach, intestine ( Motoie et al., 2009 ), salivary glands ( Masuda et al., 2003 ), seminal plasma and spermatozoa ( D'Aniello et al., 2005 ), neural system ( D'Aniello and Garcia-Fernàndez, 2006 ), knee cartilage ( Fisher et al., 2006 ), testis ( Lamanna et al., 2006 ), pre-ovulatory ovarian follicle ( D'Aniello et al., 2007 ), and retinae ( Opere et al., 2009 ). Wide existence of D-aspartate in body tissues suggests a potential physiological function in animals.…”