Profiling of lens protease involved in generation of aA-66-80 crystallin peptide using an internally quenched protease substrate

Hariharapura, Raghu (2013) Profiling of lens protease involved in generation of aA-66-80 crystallin peptide using an internally quenched protease substrate. Experimental Eye Research, 109. pp. 51-59. ISSN 0014-4835

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Abstract

Proteins of lens fiber cells are prone to accumulate extensive post-translational modifications because of very little protein turnover. Lens proteins are degraded via the lens proteolytic systems into peptides, which are subsequently hydrolyzed by downstream aminopeptidases. Inefficient degradation can lead to accumulation of protein fragments and subsequent aggregation. Previously we showed that aA-66-80 peptide and its truncated products accumulate in aging and cataract human lenses. These peptides interact with crystallins, causing crystallin aggregation and precipitation. N- and C-terminal-blocked peptides that have the cleavage sites to generate the aA-66-80 fragment were used to test lens extracts for sequence-specific proteases in lens extracts. An internally quenched fluorogenic peptide substrate containing the sequence-specific site for a lens protease to generate aA-66-80 peptide was designed, synthesized and used to characterize protease(s) that are capable of generating this peptide in bovine and human lenses. We show that proteases with the potential to generate aA-66-80 peptide are present in bovine and human lenses. We also show that the aA-66-80 peptides are resistant to hydrolysis by aminopeptidases present in the lenses and they can suppress the degradation of other peptides. Failure of complete hydrolysis of these peptides in vivo can lead to their accumulation in the lens and subsequent lens protein aggregation, which may ultimately lead to the formation of cataract.

Item Type: Article
Uncontrolled Keywords: aA-66-80 peptide ; crystallin ; cataract ; lens; protease ; peptidase ; hydrolysis.
Subjects: Pharmacy > MCOPS Manipal > Pharmaceutical Biotechnology
Depositing User: KMC Manipal
Date Deposited: 12 Mar 2013 04:40
Last Modified: 12 Mar 2013 04:40
URI: http://eprints.manipal.edu/id/eprint/78981

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