Interaction of human placental ribonuclease with placental ribonuclease inhibitor

Biochemistry ◽  
1991 ◽  
Vol 30 (8) ◽  
pp. 2246-2255 ◽  
Author(s):  
Robert Shapiro ◽  
Bert L. Vallee
Keyword(s):  
Ribonuclease Inhibitor ◽  
Placental Ribonuclease Inhibitor

scholarly journals Sensitivity of monomeric and dimeric forms of bovine seminal ribonuclease to human placental ribonuclease inhibitor

1992 ◽  
Vol 281 (2) ◽  
pp. 343-348 ◽  
Author(s):  
B S Murthy ◽  
R Sirdeshmukh
Keyword(s):  
Enzyme Activity ◽  
Gel Filtration ◽  
Enzyme Structure ◽  
Inhibitor Concentration ◽  
Ribonuclease Inhibitor ◽  
Inhibitor Study ◽  
Bovine Seminal Ribonuclease ◽  
Dimeric Form ◽  
Placental Ribonuclease Inhibitor ◽  
Assay Conditions

We have studied the inhibition of bovine pancreatic RNAase (RNAase A) and bovine seminal RNAase in its native dimeric form (RNAase BS-1) and in monomeric carboxymethylated form (MCM RNAase BS-1) by human placental RNAase inhibitor (RNAase inhibitor) in order to understand the effect of enzyme structure on its response to the inhibitor. Study of the inhibition as a function of inhibitor concentration revealed that RNAase A and MCM RNAase BS-1 were inhibited fully and the inhibitor-sensitivities of the two were comparable. But under identical inhibitor concentrations RNAase BS-1 was found to be virtually insensitive to the inhibitor; at higher (3-10-fold) inhibitor concentrations marginal inhibition of the native enzyme could be observed. When RNAase BS-1 was pretreated with 5 mM-dithiothreitol (DTT) and assayed, it exhibited greater inhibitor-sensitivity, presumably as a result of its partial monomerization on exposure to DTT. This DTT-mediated change in the response of RNAase BS-1 to the inhibitor did not, however, seem to occur either in the assay conditions (which included DTT) or even when the enzyme was pretreated with DTT in the presence of the substrate, suggesting an effect of the substrate on the enzyme behaviour towards the inhibitor. Independently, gel-filtration runs revealed that, although DTT treatment caused monomerization of RNase BS-1, this change did not take place when DTT treatment was carried out in the presence of the substrate. From our observations, we infer that differential inhibitor-sensitivity of the dimeric and monomeric forms of RNAase BS-1, the relative contents of the two forms and the influence of the substrate on them may be important determinants of the net enzyme activity in the presence of the inhibitor.

scholarly journals BINDING OF HUMAN PLACENTAL RIBONUCLEASE INHIBITOR TO EXTRACELLULAR MATRIX MOLECULES

1993 ◽  
Vol 14 (2) ◽  
pp. 123-128 ◽  
Author(s):  
TAKAHISA SHINOMIYA ◽  
NOZOMI NISHIMURA ◽  
KOICHI TAMOTO ◽  
TSUTOMU HONJOH
Keyword(s):  
Extracellular Matrix ◽  
Ribonuclease Inhibitor ◽  
Placental Ribonuclease Inhibitor
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