Linked Life Data

11758915

Source:http://linkedlifedata.com/resource/pubmed/id/11758915

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
2001-12-7
pubmed:abstractText
Site-directed mutagenesis experiments on all the conserved residues of Phe and Tyr in all the known squalene-hopene cyclases (SHCs) were carried out to identify the active site residues of thermophilic Alicyclobacillus acidocaldarius SHC. The following functions are proposed on the basis of kinetic data and trapping of the prematurely cyclized products: (1) The Y495 residue probably amplifies the D376 acidity, which is assumed to work as a proton donor for initiating the polycyclization cascade, but its role is moderate. (2) Y609 possibly assists the function of F365, which has previously been assigned to exclusively stabilize the C-8 carbocation intermediate through cation-pi interaction. The Y609A mutant produced a partially cyclized bicyclic triterpene. (3) Y612 works to stabilize both the C10 and C8 carbocations, this being verified by the finding that mono- and bicyclic products were formed with the Y612A mutant. (4) F129 was first identified to play a crucial role in catalysis. (5) The three residues, Y372, Y474 and Y540, are responsible for reinforcing the protein structure against thermal denaturation, Y474 being located inside QW motif 3.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0916-8451
pubmed:author
pubmed:issnType
Print
pubmed:volume
65
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2233-42
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
Catalytic function of the residues of phenylalanine and tyrosine conserved in squalene-hopene cyclases.
pubmed:affiliation
Department of Applied Biological Chemistry, Faculty of Agriculture, and Graduate School of Science and Technology, Niigata University, Ikarashi, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't