Biochemical Properties and Intracellular Processing of Lysosomal Cathepsins B and H

Yukio Nishimura, Hiroshi Tsuji, Keitaro Kato, Hiroshi Sato, Jun Amano, Masaru Himeno, Hiroshi Tsuji

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6 Citations (Scopus)


Lysosomal cysteine proteinases of cathepsins B and H were isolated to a homogeneous state from rat liver by employing Sephadex G-75, DEAE-Sephacel, CM-Sephadex, and Mono S column chromatography. Each of the purified cathepsins B and H was demonstrated to be composed of a mixture of a single-chain form and the processed two-chain form upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). To investigate the proteolytic maturation of lysosomal cathepsins B and H, turnover kinetics of these enzymes were studied by comparing the specific radioactivities of the incorporated [3H] leucine into either the single-chain form or two-chain form in vivo. The specific radioactivity derived from each protein band of lysosomal cathepsin H in SDS-PAGE at 1, 3, 6, 12, 24 and 48h after the injection of a radiolabel showed that the peak of specific radioactivity of the single-chain form of cathepsin H appeared at 6h and that after 6h, the radiolabel was sequentially incorporated into the two-chain form, while the radiolabel in the single-chain form started to gradually decrease, suggesting that the single-chain form was processed to generate the mature enzyme after the enzyme was incorporated into the lysosomes. In contrast, in the case of cathepsin B, the appearance of a radiolabel in the single-chain form or in the two-chain form was observed almost concomitantly without time lag, indicating that the processing of cathepsin B occurred very rapidly in the lysosomes.

Original languageEnglish
Pages (from-to)829-836
Number of pages8
JournalBiological and Pharmaceutical Bulletin
Issue number6
Publication statusPublished - 1995

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Pharmaceutical Science


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