ABSTRACT
The presence of D-amino acid in proteins is thought to be a result of racemization of L-amino acid,which may influence the space structure and the functions of proteins and the connection to the occurence of some diseases has been demonstrated.Recently,tremendous advancement in instrumental techniques has brought the rapid development to analytical methods and detecting techniques in the research on racemization of protein amino acid.The advances in the relationship between racemizadon of protein amino acid and diseases,the influence factors on racemization of protein amino acid and the analytical techniques are reviewed in this article,and the research directions of racemization of protein amino acid are also given.
ABSTRACT
Racemization is probably the most abundant post-translational modification (PTM) in aged lens.According to previous studies,L-amino acid in α,β and γ crystallins are tend to transfer into D-amino acid with aging,leading to a series of age-related changes in the structure,metabolism and function of lens.Aggregated highmolecular-weight proteins gradually accumulate in both nuclear and cortex region,which will have a negative effect on the function of crystallins and finally lead to capacity of lens.Moreover,it is likely that racemization of crystallins eventually leads to cataract formation and development as well.The material effect and mechanism of racemization changes in human age-related lens still requires further research.
ABSTRACT
La determinación de la edad al momento de la muerte sobre la base de la recemización del ácido aspártico (AAR) en la dentina humana se ha aplicado con éxito en odontología forense desde hace varios años. El uso de este procedimiento en la dentina proporciona una solución sencilla y rentable, cuyo método puede lograr una presición de más menos 3 años. Actualmente esta determinación no se encuentra estandarizada, inconsistencia que se debe resolver si se pretende aplicar con éxito la técnica para la determinación de la edad en casos de interés forense. Se pretende aplicar con éxito la técnica para la determinación de la edad en casos de interés forense...
Subject(s)
Humans , Aspartic Acid/analysis , Age Determination by Teeth , Dentin , Forensic MedicineABSTRACT
OBJECTIVE:To study the process of acetylized racemization of D-penicillamine in the acidic condition. METHODS:The acetylized racemic mixture of D-penicillamine was prepared by racemizing acetyl chloride in acetic acid solu_tion with D-penicillamine as feedstock.The preparation process was optimized with the quantities of solvent and acetyl chloride,the reaction temperature,the reaction time etc.as parameters.The influence of reaction temperature,reaction time on the specific optical rotation in the acetylized process was determined and the kinetic equation of acylation process was computed. RESULTS:The optimal condition for racemization was the following,the quantity ratios of D-penicillamine-acetic acid -acetyl chloride were 1∶7∶2,the reaction temperature was 80℃ and the reaction time was 5h.The kinetic equation of acylation process fitted first order linear relation. CONCLUSION:This preparation process is mild and simple,and it offers direct feedstock for the preparation of D,L-penicillamine.
ABSTRACT
Disasteromeric dipeptides were derived fromthe amino acid enantiomers in dentin by O-Phtha-ladehyde-N-acetyl-L-cysrteine The products were seperated with High Performance Liquid Chromatography (HPLC) and were detected by fluorscece detector The . D / L ratio of aspartic acid in dentin of 20 first premolars was determined with the method, The interrelation coefficient between the D/L ratio of aspartic acid and actual age was 0. 9889. The etiamating error of ?one year of age was 40% , No estimating error exceeded five years of age was encountered.