Presence of an endopeptidase activity in rat liver ribosomes
Langner, J.; Ansorge, S.; Bohley, P.; Welfle, H.; Bielka, H.
Acta Biologica et Medica Germanica 36(11-12): 1729-1733
1977
ISSN/ISBN: 0001-5318 PMID: 616719 Document Number: 112171
Preparation of ribosomes using different procedures (treatment of postmitochondrial-postlysosomal supernatant or microsomes with 1% triton in 0.15 or 0.5 M KCl and subsequent sucrose gradient centrifugation; treatment of microsomes with 1.5% deoxycholate/2% triton) results in purified ribosomes which contain an endopeptidase activity detectable by breakdown of ribosomal proteins to trichloroacetic acid soluble split products. The proteolytic activity can be recovered also in the extracted proteins of whole ribosomes. With ribosomes the pH optimum of proteolytic breakdown is at about 7. The inhibition of the activity by leupeptin, DIFP and soya bean trypsin inhibitor suggests a serine type of the proteolytic activity.