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M I Leviant

Publications and source records attributed to M I Leviant.

9 recordsLinked to original sources
PubMed1979

[Inhibitors of cathepsin R (ribosomal proteinase). Polyamines as natural inhibitors of the proteinase].

The effects of potential inhibitors on the activity of neutral ribosomal proteinase--cathepsis R--were studied. It was found that cathepsin R belongs to the group of serine enzymes. The polyamines spermine and spermidine, which are inherently present in the ribosomes, are natural reversible inhibitors of cathepsin R. Upon separation of the enzyme from the inhibitors the proteinase displays a high activity. The effects of polyamines on the proteinase activity may either be direct or mediated via RNA. The enzyme activity can also be controlled by amino acids. Approximately 2/3 of cathepsis R were found in a latent state.

Animals↗
PubMed1978

[On the localization of ribosomal proteinase].

The localization of proteolytic activity in rat liver ribosomes was studied. 40S and 60S subparticles were obtained upon dissociation of polyribosomes by puromycin. It was shown that the proteolytic activity is associated with small subparticles or with proteins removed from the latter.

Animals↗
PubMed1978

[Specificity of neutral ribosomal protease].

The specificity of the ribosomal proteinase was studied using a variety of substrates: nascend peptides, ribosomal proteins, B-chain of insulin and some synthetic peptides (the heptapeptide Gly-Phe-Phe-Tyr-Thr-Pro-Lys; the hexapeptide Gly-Phe-Leu-Gly-Phe-Leu and the CBZ-hexapeptide; the tripeptide Phe-His-Leu and the CBZ-tripeptide). It was shown that in the heptapeptide tested the enzyme cleaved most rapidly the Phe-Tyr bond; the Phe-Phe bond was cleaved less rapidly. The rest of the peptide bonds in the heptapeptide were also cleaved and by the end of the incubation the cleavage was complete. All the other substrates tested also underwent complete degradation. The data obtained allowed us to classify the enzyme with the group of endopeptidases with broad specificity of action. The possibility cannot be excluded that the broad specificity observed is due to the presence of more than one enzyme on the polyribosomes.

Endopeptidases↗