Purification and characterization of cathepsin D from herring muscle ( Clupea harengus )

L.B. Nielsen, Henrik Hauch Nielsen

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Cathepsin D was purified and concentrated 469-fold from a homogenate of Clupea harengus muscle. The purified enzyme is a monomer with a molecular weight of 38 000-39 000. It is inhibited by pepstatin and has optimal activity at pH 2.5 with hemoglobin as the substrate. The isoelectric point is at pH 6.8. Glycosidase treatment and binding to Concanavalin A indicated that the enzyme contains one N-linked carbohydrate moiety of the high-mannose type per molecule. The first 21 amino acid residues of the N-terminal showed high similarity to cathepsin D from antarctic icefish liver (Chionodraco hamatus) and trout ovary (Oncorhynchus mykiss). Digestion of the P-chain of oxidized insulin resulted in preferential cleavage at Leu(15)-Tyr(16), (47%), Tyr(16)-Leu(17) (34%) and Ala(14)- Leu(15) (18%). Incubation with myofibrils from herring muscle at pH 4.23 showed that the enzyme mainly degraded myosin, actin and tropomyosin. (C) 2001 Elsevier Science Inc. All rights reserved.
Original languageEnglish
JournalComparative Biochemistry and Physiology B-Biochemistry & Molecular Biology
Volume128B
Issue number2
Pages (from-to)351-363
ISSN1096-4959
Publication statusPublished - 2001

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