Diabetes mellitus is an incurable disease, so it is necessary to establish a model to screen biomarkers for early warning in order to minimize the likelihood of long-term complications. Current- ly, advanced glycation end products （AGEs） are considered to be biomarkers of many diseases, such as diabetes and its complications. In this study, a model for further proteomics study was es- tablished to analyze the glycation of HSA with 18 O-labeling strategy. 30 peptides were randomly se- lected to optimize tryptic digestion and 18O-labeling condition by HPLC-ESI/TOF. The best tryptic di- gestion condition was： HSA： Trypsin = 50： 1, w/w for 20 h. The best t8 O-labeling condition was to di- lute urea to 1 M and adjust KH2 POa--K2 HPO4 buffer pH to 6.0 to give a final labeling efficiency of 98.5 ± 0.7%. The inter- and intra-day precisions and stability were satisfactory. This model was es- tablished and optimized for further quantitative proteomics study.
The CP4-EPSPS gene is widely used in herbicide-tolerant plants/crops all over the world. In this study, a method was developed by coupling liquid chromatography with high sensitivity to tandem mass spectrometry to quantify the amount of CP4-EPSPS expression in Nicotiana tabacum leaves. The quantification of protein was converted to measure the unique peptide of CP4-EPSPS protein. One peptide unique to CP4-EPSPS was synthesized and labeled with.H2^18O to get 180 stable isotope labeled peptide. The peptide served as the internal standard. The validated method had good specificity and linearity. The intra-and inter-day precisions and accuracy for all samples were satisfactory. The results demonstrated that the novel method was sensitive and selective to quantify CP4- EPSPS in the crude extract without time-consuming pre-separation or.the purification procedures.
Aging refers to a multidimensional process that all changes were accumulated in a person over time.These aging changes are associated with progressive increases in the chance of disease and death. Thus,it is necessary to establish a model to screen biomarkers to characterize and evaluate aging degree. In this study,an in vitro aging model was set up by formaldehdye and human serum albumin（ HSA）,the most abundant protein in human plasma,based on Maillard Reaction. The liquid chromatography tandem mass spectrometry（ LC-MS /MS） method with ^18O-labeling technique was employed to quantify modification degree of peptides cleaved from HSA. This model was established and optimized for further quantitative biomarker study.
