Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.1.2.13 (aldolase)
 3,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cathepsin H purified from porcine spleens was studied for its specificity against various peptide and denatured protein substrates. The enzyme degraded all peptide substrates exclusively by an aminopeptidase activity. The enzyme preferentially released NH2-terminal amino acid residues with large hydrophobic (Phe, Trp, Leu, and Tyr) or basic (Arg and Lys) side chains. Amino acids containing small or polar side chains were not released. Peptides with a proline in the NH2-terminal or penultimate positions were not hydrolyzed either. Large polypeptides such as reduced and carboxymethylated soybean trypsin inhibitor and aldolase were not degraded. These results indicate that cathepsin H is an exopeptidase but not an endopeptidase. We propose that the biological role of this enzyme is the degradation of tissue proteins in lysosomes by its aminopeptidase activity.
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PMID:Porcine spleen cathepsin H hydrolyzes oligopeptides solely by aminopeptidase activity. 339 49

Two SH-dependent proteinases (I and II) active in neutral media were isolated from bovine spleen and purified to apparent homogeneity. The histone-hydrolyzing activity of proteinase I was increased 3500-fold as compared to that of the original extract. Proteinase I hydrolyzed a variety of proteins (histones, azocasein, hemoglobin, collagen) but did not hydrolyze low molecular weight synthetic substrates, such as BAPA, BANA, BAEE, ATEE, Leu-beta-NA, Arg-beta-Na and Ala-beta-NA. The molecular weight of the enzyme as determined by SDS electrophoresis was found to be about 23,000. Isoelectrofocusing of the enzyme resulted in one major component with pI of 6.05 and in two minor components with pI of 6.2 and 6.4. Proteinase II hydrolyzed Leu-beta-NA, Arg-beta-NA and Ala-beta-NA but did not hydrolyze beta-naphthylamides of dicarboxylic acids and Gly-Phe-beta-Na. This proteinase split BANA and histone and very slowly split azocasein and collagen. Proteinase II was found to have a molecular weight of 30 000 and a pI of 6.8-6.9. Proteinase I inactivated fructose-1.6-diphosphate aldolase, partly inactivated glucose-6-phosphatase dehydrogenase and caused activation of phosphodiesterase of cyclic nucleotides. Proteinase II had no effect on the activity of the above enzymes. A comparison of proteinase I and II with enzymes described in literature demonstrated that the former was cathepsin L, while the latter was cathepsin H from spleen.
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PMID:[Characteristics of two thiol proteinases from spleen active in neutral media]. 675 12

In vivo proteolytic modification of liver aldolase on administration of leupeptin, a thiol proteinase inhibitor of microbial origin, is reported. When leupeptin was injected into rats, the activity of aldolase in the liver decreased to 40% of that in control rats. Molecular properties of aldolase isolated from the livers of control rats and leupeptin-treated rats indicated that a decrease of aldolase activity is attributable to hydrolysis of a peptide linkage(s) near the carboxyterminal of the enzyme. Injection of leupeptin also caused marked increase in the activities of free lysosomal proteinases, such as cathepsin A and cathepsin D and moderate increase of cathepsin B and cathepsin L. Increase in free activity of cathepsin A returned to the level of control rats by 12 hr after injection of leupeptin, whereas 36 hr was required for recovery of decreased aldolase activity. When insulin was coinjected with leupeptin, increase in the activity of free cathepsin A and decrease of activity of aldolase produced by the injection of leupeptin was prevented. These findings indicate that modification of aldolase may be due to action of a lysosomal protease(s). Incubation of the purified aldolase with the lysosomal fraction produced the same changes in properties of aldolase as those observed in vivo on injection of leupeptin. The aldolase inactivating proteinase in the lysosomal fraction was inhibited by PMSF and leupeptin and not by pepstatin. Purified cathepsin A (a serine proteinase), cathepsin B and cathepsin L (thiol proteinase) are potent inactivators of aldolase but cathepsin H and cathepsin D are not. Cathepsin A, B and L are involved in inactivation of aldolase in lysosomes. Endogenous thiol proteinase inhibitor which inhibits lysosomal thiol proteinases (cathepsin B, L and H) is found in the cytosol fraction of liver. The level of thiol proteinase inhibitor actually decreased to 60% of that in control rats in leupeptin-treated rats, suggesting that non-thiol proteinase cathepsin A is a major factor in inactivation of aldolase in lysosomes. Not only leupeptin but also other proteinase inhibitors (antipain, E-64-D, chloroquine) caused increase of labilization of the lysosomes and decrease in aldolase activity. Physiological stimuli which are known to induce the labilization of the lysosomal membrane, such as starvation and glucagon, caused slight or no significant increase of activities of free cathepsin A and D and resulted in no apparent change in aldolase activity.
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PMID:Modification of rat liver fructose biphosphate aldolase by lysosomal proteinases. 705 71

A simple purification scheme was developed for isolation and purification of cathepsin B from buffalo kidney. The use of CM-Sephadex and chromatofocusing helped in better and simultaneous separation of cathepsin B, H and L. As judged by PAGE and SDS-PAGE studies, the enzyme was found to be pure on the basis of charge and had a molecular mass of 25.5 kDa. The amino acid composition, number of free sulfhydryl groups and other major physico-chemical properties of the purified enzyme were similar to the properties reported for cathepsin B from other sources/tissues. However, the NH2-terminal amino acid residue of the enzyme was found to be Ala as against Leu reported from other tissues/species. The total carbohydrate content was also found to be significantly lower (3.6%) as compared to 7.0-7.6% reported for the enzyme from other sources. Thiol reducing compounds activated the enzyme whereas thiol blocking compounds inhibited it. The buffalo kidney enzyme hydrolyzed Z-Phe-Arg-MCA (Vmax/K(m) = 17.1) as the most efficient substrate followed by Z-Arg-Arg-MCA, BANA and BAPNA. Among the protein substrates, goat hemoglobin (Vmax/K(m) = 874) was found to be the most preferred. Rabbit muscle aldolase, usually considered to be a good substrate for cathepsin B, proved to be a poor substrate for this enzyme; only 25-30% inactivation of aldolase was observed. Antibodies raised against the enzyme recognised only cathepsin B and did not have any cross reactivity with cathepsin H or L from the same or different sources. These differences in the properties of the buffalo kidney enzyme vis-a-vis the same enzyme from other tissue/species have been attributed to specialized function of cathepsin B in diversified tissues.
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PMID:Purification and tissue/species dependence of the specificity of buffalo kidney cathepsin B. 959 26