DILATED CARDIOMYOPATHY - COMPUTER-ASSISTED ANALYSIS OF ENDOMYOCARDIALBIOPSY PROTEIN-PATTERNS BY 2-DIMENSIONAL GEL-ELECTROPHORESIS

In order to identify disease-associated alterations in the myocardial protein patterns in dilated cardiomyopathy, we used 2-dimensional gel electrophoresis to analyse the proteins of endomyocardial biopsies fro m patients and controls. Proteins (150 mu g) from biopsies (1-3 mg wet weight) were first separated by isoelectric focusing, then applied to large 2-dimensional gels. A computer-assisted system (PDQUEST (R)) wa s used for spot detection, quantification and comparison of 2-dimensio nal protein patterns. From a single endomyocardial biopsy about 1000 d ifferent protein species were resolved. The spot pattern was influence d by the concentration of protein during sample preparation, by the am ount of protein loaded onto the gels and by the development time of si lver staining. Variances of spot position in the first and second dime nsion and in the long diagonals were less than 5%. Coefficients of var iance for the spot quantities in 8 gels were 16 +/- 8%. Contaminating blood proteins could be identified in the biopsy patterns. Computer-as sisted comparison between cardiomyopathy (n = 5) and controls (n = 5) over the whole gel revealed that 55 protein spots were increased 100%, 27 protein spots decreased 100%. Four proteins showed significant qua ntitative differences between the cardiomyopathic hearts and controls. Fourteen proteins were identified by amino acid analysis or microsequ encing. An isoelectric point and molecular mass grid was laid over the whole gel based on these identified protein species, resulting in app roximate isoelectric point values and molecular masses for all other p rotein species. Thus, myocardial 2-dimensional protein patterns obtain ed from endomyocardial biopsies can be used for the characterization o f cardiac diseases.