Purification and characterization of lens specific calpain (Lp82) from bovine lens

Yoji Ueda, Ashley L. McCormack, Thomas R. Shearer, Larry L. David

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

Ubiquitous type m-calpain and lens specific Lp82 calpain were separated and partially purified from fetal bovine lens and the enzymatic characteristics were compared. Lens m-calpain required 200 μM calcium for 1/2 maximal activity, while Lp82 required 30 μM. Both types of calpains were inhibited by 0.1 mM E64, and 5 mM iodoacetamide, but not by 1 mM phenylmethylsulfonyl fluoride. Lp82 was insensitive to 1 μM calpastatin peptide while m-calpain was effectively inhibited. In the presence of calcium, m-calpain lost most of its activity within 2 hr, while Lp82 was continually active for 18 hr. Both calpains cleaved the natural substrates βA3 and αB crystallins in a similar manner. However, incubation of αA crystallin with m-calpain removed ten amino acid residues from its C-terminus, while incubation with Lp82 removed only five residues. The latter truncation product of αA was also found in vivo. These data suggested that Lp82 may have a more important role than m-calpain in modification of crystallins during lens maturation.

Original languageEnglish (US)
Pages (from-to)625-637
Number of pages13
JournalExperimental Eye Research
Volume73
Issue number5
DOIs
StatePublished - Jan 1 2001

Keywords

  • Alpha crystallin
  • Beta crystallin
  • Bovine lens
  • Lp82: m-calpain
  • Mass spectrometry
  • Maturation
  • Proteolysis

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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