Purification and polypeptide composition of corpora amylacea from aged human brain.

Corpora amylacea (CA) accumulation in the brain is a normal correlate of ageing. The presence of a small amount of protein in these polyglucosan bodies is a consistent finding, although the nature of this protein material remains unknown. Using sucrose gradient fractionation and density centrifugation on Percoll, a method was developed to obtain highly pure preparations of CA from human brain. The protein content of isolated CA was estimated to be approx. 4% of the total fraction by weight. SDS-PAGE analysis of CA fractions showed several polypeptide bands with molecular weights ranging from 24 to 133 kDa. Four of these bands with molecular weights of 133, 94, 42 and 24 kDa are more abundant. Thus, pure preparations of CA can be obtained that are suitable for protein analysis.