Document Detail

Characterization of the extracellular ribonuclease of Tetrahymena pyriformis W.
MedLine Citation:
PMID:  1920145     Owner:  NLM     Status:  MEDLINE    
Several investigations have indicated that Tetrahymena pyriformis secretes ribonuclease activity into culture media. The extracellular ribonuclease from strain W has been purified and partially characterized. The molecular weight was determined by gel filtration to be 26,500. The amino acid composition of the enzyme was compared with those of the three intracellular ribonucleases characterized by Trangas, and substantial differences were demonstrated. The extracellular enzyme hydrolyzed both polyadenylic and polyuridylic acids, indicating lack of absolute base specificity. The hydrolysis of polyadenylic acid followed normal Michaelis-Menten kinetics, but substrate inhibition occurred at high concentrations of polyuridylic acid. The hydrolysis of polyuridylic acid was competitively inhibited by 2'- and 3'-cytidine, guanine, and uridine nucleotides, and by 2'AMP. No inhibition of the hydrolysis of Torula yeast RNA was detected. The kinetic properties of the extracellular ribonuclease are compared with those of the intracellular enzymes.
T McKee; D J Prescott
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of protozoology     Volume:  38     ISSN:  0022-3921     ISO Abbreviation:  J. Protozool.     Publication Date:    1991 Sep-Oct
Date Detail:
Created Date:  1991-10-30     Completed Date:  1991-10-30     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  2985197R     Medline TA:  J Protozool     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  465-71     Citation Subset:  IM    
Department of Biology, Bryn Mawr College, Pennsylvania 19010.
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MeSH Terms
Amino Acids / analysis
Chromatography, Thin Layer
Electrophoresis, Polyacrylamide Gel
Isoelectric Focusing
Molecular Weight
Ribonucleases / chemistry,  metabolism*
Tetrahymena pyriformis / enzymology*
Reg. No./Substance:
0/Amino Acids; EC 3.1.-/Ribonucleases

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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