Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.1.52 (PNGase F)
 1,527 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cathepsin B was purified from normal human liver and several human tumour tissues and partially characterized. Three forms of cathepsin B, with molecular masses of 25 kDa, 26 kDa (the two appearing as a doublet) and 30 kDa, were detected in SDS/polyacrylamide gels. The 25-26 kDa doublet was associated with the fractions from tumours and normal liver containing the highest cathepsin B activity. Cathepsin B from both sources showed similar pH optima. Both normal liver and tumour cathepsin B exhibited similar kinetics against selected synthetic substrates. At neutral pH and 24 degrees C, cathepsin B from both normal liver and tumour exhibited a lower Km and a higher kcat./Km than at pH 6.0. Their inhibitory profiles against synthetic inhibitors were also similar. Immunological studies with a monospecific antibody against the mature double-chain form of human liver cathepsin B and an antibody against a cathepsin B-derived synthetic peptide established the immunological similarity of liver and tumour enzymes. The N-terminal sequences of the 25 kDa and 26 kDa forms were identical with that of the heavy chain of the mature double-chain form of human cathepsin B, whereas the N-terminal sequence of the 30 kDa species was identical with that of the single-chain form of human cathepsin B. Treatment of the double-chain form of cathepsin B from normal liver and tumours with the endoglycosidase peptide-N4-(N-acetyl-beta-glucosaminyl)asparagine amidase converted the 26 kDa form into 25 kDa in SDS/polyacrylamide gels, suggesting that cathepsin B may exist as both glycosylated and unglycosylated forms. Our results, in contrast with those reported earlier for mouse cathepsin B, indicate that human liver and tumour cathepsin B are similar.
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PMID:Human tumour cathepsin B. Comparison with normal liver cathepsin B. 163 35

Western blots, enzyme assays, protein glycosylation studies, and immunohistochemical staining were used to characterize cathepsin B expression at successive stages of colorectal tumor progression. In normal colon mucosa and premalignant adenomas, cathepsin B expression was predominantly due to mature two-chain protein detected on Western blots as the nonglycosylated 27-kDa form, with overexpression of this protein occurring in only 4 of 18 adenomas. Overexpression increased significantly in Dukes A and B carcinomas (26 of 37 cases), with cathepsin B protein generally detectable in carcinomas as a combination of both 27-kDa nonglycosylated and 28-kDa glycosylated mature two-chain forms. Glycosylated cathepsin B protein in carcinoma extracts was sensitive to PNGase F but resistant to Endo H, indicating a pattern consistent with complex rather than high mannose type glycosylation. When sorted by advancing tumor stage, peak expression of cathepsin B protein occurred in carcinomas involved in local invasion compared with adenomas or metastatic cancers. At all stages, cathepsin B activity correlated significantly with the levels of heavy chain mature cathepsin B protein (r = 0.6682, p < 0.0001) irrespective of glycosylation. Immunohistochemical staining of cathepsin B protein revealed fine diffuse cytoplasmic staining in both adenomas and carcinomas compared with coarse granular cytoplasmic staining (typical of lysosomes) seen in matched normal mucosa. Our results demonstrate several sequential, apparently independent changes in cathepsin B expression during colorectal tumor progression including early changes in subcellular localization, up-regulation of cathepsin B protein and activity in invasive cancers, and altered protein glycosylation detected in malignant tumors at all stages.
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PMID:Elevations in cathepsin B protein content and enzyme activity occur independently of glycosylation during colorectal tumor progression. 936 Sep 97

The major cathepsin B-like proteinase of adult Schistosoma japonicum has been isolated for the first time. Affinity chromatography with the mammalian cathepsin B inhibitor glycyl-phenylalanyl-glycine-semicarbazone purified a protein that was identified by N-terminal sequencing as Sj31. Sensitivity of Sj31 to PNGase F demonstrated the presence of asparagine-linked N-glycan. Marked resistance to the action of Endo-beta-glycosidase H indicated that most of the N-glycan chains are of the complex type. Binding of horseradish peroxidase-conjugated lectins demonstrated the presence of N-mannose, N-acetylglucosamine, and N-acetyllactosamine type 2 in the N-glycan. Fucose was not detected, and the presence of sialic acid remained questionable. Sj31 degraded the fluorogenic substrates Z-Phe-Arg-NMec and Z-Arg-Arg-NMec with an optimum between pH 5.0 and 6.0. The specific activity was 18-21-fold higher with the Phe-Arg substrate compared with the Arg-Arg substrate, whereas this value was 4-6-fold for bovine spleen cathepsin B, thus suggesting differences in the S2 subsite between parasite and host proteinases. Quantitative purification of Sj31 led to the conclusion that cathepsin B-like activity predominates over cathepsin L-like activity in S. japonicum. Because Sj31 degraded hemoglobin in vitro and was localized in the parasite gut, the proteinase may degrade ingested proteins in vivo.
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PMID:Affinity isolation and characterization of the cathepsin B-like proteinase Sj31 from Schistosoma japonicum. 940 88