GLYCOXIDATIVE MODIFICATION OF ADENOSINE continued
Figure 5 – Reaction scheme for the detection of CMAd from glycoxidation reactions and fasting human urine sample.
The authors’ previous work involved the detection of carboxymethyl-2’- deoxyadenosine (CMdA) and carboxymethyl-2’-deoxycytidine (CMdC) from in vitro glycoxidation reactions, fasting urine specimens, calf thymus and human serum DNA of diabetic persons.14,15
More recent studies dem-
onstrate that CMdA and CMdC can be used as an indicator for diabetes in obese persons.16,17
These findings led the researchers to believe that DNA
molecules are also modified by glycoxidation reactions. Similar modifica- tion in RNA nucleoside adenosine is a possibility.
The identity of the CMAd compound from glycoxidative reactions of adenosine with D-glucose and D-ribose was investigated using HPLC and LC/MS-ESI (Figures 1a and b). The identity of the CMAd compound was confirmed by synthesizing CMAd using adenosine and chloroacetic acid raw materials (Figure 1c). CMAd compound was identified in both diabetic and nondiabetic obese urine samples by HPLC, LC/MS and triple quadru- pole mass spectrometry (MS-MS) using the M+H+
326 ion as a criterion for
detection in mass spectrometry analysis (Figures 2b and 3b). The presence of the glycoxidatively produced and in vitro-identified carboxymethyl derivative (CMAd) in urine samples from human subjects was confirmed by HPLC and LC/MS-ESI.
CMAd was identified in the mixing experiment with synthesized CMAd and fasting human urine sample using HPLC and LC/MS-ESI (Figures 2c and 3c). These experiments proved that CMAd is produced in human sys- tems. The authors first reported that CMAd was present in fasting urine samples from both diabetic and nondiabetic obese persons.18
The results
of these experiments indicate the biological relevance of the above RNA derivatives, suggesting that glycation reactions are a possible source of complications in diabetes involving RNA macromolecules.
References
1. Ahmed, M.U.; Thorpe, S.R. et al. Identification of NE-carboxymethylly- sine as a degradation product of fructoselysine in glycated proteins. J. Biol. Chem. 1986, 261, 4889–94.
2. Baynes, J.W. Role of oxidative stress in development of complications in diabetes. Diabetes 1991, 40, 405–12.
Figure 4 – Distribution of BMI, fasting BGL and HbA1c in the three study groups.
3. Ahmed, M.U.; Dunn, J.A. et al. Oxidative degradation of glucose adducts to protein. Formation of 3-(N epsilon-lysino)-lactic acid from model compounds and glycated proteins. J. Biol. Chem. 1988, 263, 8816–21.
4. SAS for Windows. Version 9.2. SAS Institute Inc., Cary, N.C. AMERICAN LABORATORY • 38 • AUGUST 2015
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52