Linked Life Data

9748220

Source:http://linkedlifedata.com/resource/pubmed/id/9748220

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
40
pubmed:dateCreated
1998-11-12
pubmed:abstractText
The kinetics of the hydrolysis of cytidine 2',3'-cyclic phosphate (C>p) to 3'-CMP by ribonuclease A are multiphasic at high substrate concentrations. We have investigated these kinetics by determining 3'-CMP formation both spectrophotometrically and by a highly specific and quantitative chemical sampling method. With the use of RNase A derivatives that lack a functional p2 binding subsite, evidence is presented that the abnormal kinetics with the native enzyme are caused by the sequential binding of the substrate to the several subsites that make up the active site of ribonuclease. The evidence is based on the following points. 1) Some of the unusual features found with native RNase A and C>p as substrate disappear when the derivatives lacking a functional p2 binding subsite are used. 2) The kcat/Km values with oligocytidylic acids of increasing lengths (ending in C>p) show a behavior that parallels the specific velocity with C>p at high concentrations: increase in going from the monomer to the trimer, a decrease from tetramer to hexamer, and then an increase in going to poly(C). 3) Adenosine increases the kcat obtained with a fixed concentration of C>p as substrate. 4) High concentrations of C>p protect the enzyme from digestion with subtilisin, which results in a more compact molecule, implying large substrate concentration-induced conformational changes. The data for the hydrolysis of C>p by RNase A can be fitted to a fifth order polynomial that has been derived from a kinetic scheme based on the sequential binding of several monomeric substrate molecules.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
2
pubmed:volume
273
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
25565-72
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
The subsites structure of bovine pancreatic ribonuclease A accounts for the abnormal kinetic behavior with cytidine 2',3'-cyclic phosphate.
pubmed:affiliation
Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't