COMPARISON OF DETERGENT AND PROTEASE ENZYME COMBINATIONS FOR THE DETECTION OF SCRAPIE-ASSOCIATED FIBRILS FROM THE CENTRAL-NERVOUS-SYSTEM OFSHEEP NATURALLY AFFECTED WITH SCRAPIE

Standardized samples of tissue from the central nervous system of four sheep naturally affected with scrapie and from four healthy control s heep were subjected to a centrifugal extraction technique used to obta in scrapie-associated fibrils; the latter were then demonstrated by ne gative-contrast transmission electron microscopy. This regime was used to evaluate the fibril yield obtained from the 25 possible combinatio ns of five different detergents and five different proteolytic enzymes . N-lauroylsarcosine detergent was found to be the most efficient dete rgent for all five enzymes, followed by sulphabetaine 3-14. Sodium dod ecyl sulphate detergent was successful only in combination with a subt ilisin Carlsberg enzyme. Octylglucoside and nonidet P40 detergents did not produce fibrils with any of the enzymes. Proteinase K was the lea st efficient of the five enzymes when used in combination with N-lauro ylsarcosine; subtilisin Carlsberg, clostripain, pronase and trypsin en zymes all gave higher fibril yields. A combination of N-lauroylsarcosi ne detergent and subtilisin Carlsberg proteolytic enzyme gave the high est fibril yield. (C) 1997 W.B. Saunders Company Limited.