Cathepsin D. Purification of isoenzymes from human and chicken liver
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1. The Barrett (1967) assay for cathepsin D was slightly modified. 2. The enzyme was purified from liver of man and chicken by a procedure involving autolysis, acetone fractionation, ion-exchange chromatography and isoelectric focusing. 3. Several isoenzymes of cathepsin D were resolved in the isoelectric-focusing step, and three major forms, α,β and γ, were distinguished for each species. 4. A modified analytical method of isoelectric focusing in polyacrylamide gel indicated a high degree of homogeneity of the purified β and γ isoenzymes from each species, and this was supported by their constant high specific activities. 5. Gel filtration of the isoenzymes in a calibrated column of Sephadex G-100 showed that each had a molecular weight of 45000. 6. Human cathepsin D had a pH optimum of 3.5, and that of chicken enzyme was 3.0, haemoglobin being used as substrate. In each species, the three isoenzymes have the same pH-dependence curve. 7. The purified cathepsin D samples showed very little action on acid-denatured albumin.
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CTSD activation optimally requires an intralysosomal pH of ~4.0-4.5.
“a process optimally requiring an intralysosomal pH of ϳ4.0 -4.5 (Barrett, 1970;Cunningham and Tang, 1976).”
From Lysosomal Dysfunction in Down Syndrome Is APP-Dependent and Mediated by APP-βCTF (C99) (2019) · cites this paper as Barrett, 1970
The paper identifies cathepsin D as a lysosomal enzyme and reports that its activity depends on acidic pH. In the section on pH effects (page unavailable), however, the measured activity optima are about 3.5 for human and 3.0 for chicken cathepsin D under the assay conditions. It does not establish that activation inside lysosomes optimally requires pH 4.0–4.5. (LLM, conf=0.86)
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Research works printed but not linked: 2
- Barrett, A. J. (1969a). In Ly8o8ome8 in Biology and Pathology, vol. 2, p. 245. Ed. by Dingle, J. T. & Fell, H. B. Amsterdam: North-Holland Publishing Co.
- Press, W. M., Porter, R. R. & Cebra, J. (1960). Biochem. J. 74,501.
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Jiang, Y., Sato, Y., Im, E., Berg, M., Bordi, M., Darji, S., Kumar, A., Mohan, P. S., Bandyopadhyay, U., Diaz, A., et al. (2019) · The Journal of Neuroscience · doi:10.1523/jneurosci.0578-19.2019 · Cited by 166 · see citing works
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Hata, M., Ikeda, H. O., Iwai, S., Iida, Y., Gotoh, N., Asaka, I., Ikeda, K., Isobe, Y., Hori, A., Nakagawa, S., et al. (2018) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.1717338115 · Cited by 70 · see citing works
- Authors
- Barrett, A. J.
- Affiliations
- Tissue Physiology Department, Strangeways Research Laboratory, Cambridge CB1 4RN, U.K.
- Corresponding author
- Barrett, A. J.
- ORCID
- Barrett, A. J.
- Venue
- Biochemical Journal
- Publisher
- Portland Press Ltd.
- Published
- 1970-04-01
- Volume
- 117
- Issue
- 3
- Pages
- 601-607
- ISSN
- 0306-3283 (ISSN-L)
- PMC
- PMC1178965
- OpenAlex
- W2222227825
- Cited by
- 273
- References
- 0
- Citations by year
- 2025: 3 · 2024: 1 · 2022: 2 · 2021: 2 · 2020: 12 · 2019: 4 · 2018: 5 · 2017: 3 · 2016: 2 · 2015: 1 · 2014: 3 · 2013: 1 · 2012: 4
- FWCI
- 11.59
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Biochemical Journal (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Cancer Research › Protease and Inhibitor Mechanisms
- Health Sciences › Medicine › Oncology › Peptidase Inhibition and Analysis
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Calpain Protease Function and Regulation
- Keywords
- cathepsin D, isozymes, enzyme purification, human liver, chicken liver, isoelectric focusing, polyacrylamide gel electrophoresis, ion-exchange chromatography, acetone fractionation, autolysis, molecular weight, pH optimum
- MeSH terms
- Acetone, Animals, Cathepsins, Chickens, Chromatography, Gel, Chromatography, Ion Exchange, Humans, Hydrogen-Ion Concentration, Liver, Molecular Weight, Serum Albumin, Bovine
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