MICROSEQUENCING OF BOVINE CEREBROSPINAL-FLUID APOLIPOPROTEINS - IDENTIFICATION OF BOVINE APOLIPOPROTEIN-E

In studies of bovine plasma lipoproteins, apolipoprotein E (apoE) was not found associated with a-lipoproteins isolated over a broad range o f densities. However, studies of cerebrospinal[ fluid (CSF) lipoprotei ns from other mammals have shown that apoE is a major apolipoprotein a ssociated with high density lipoprotein, a fact that prompted us to de termine if this were also the case in bovine CSF. CSF samples were obt ained from animals with a surgically implanted catheter. Most analyzed samples were obtained from cows at various stages of the postpartum p eriod; however, a few samples also were obtained at term or during pre gnancy. Analyses of isolated ultracentrifugal fractions by polyacrylam ide gel electrophoresis revealed the presence of two ape, with the exp ected molecular weights for apoE and apoA-1. By using both matrix-assi sted laser desorption mass spectrometry and microsequencing techniques , we demonstrated that these apo are indeed apoE and apoA-1.