Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.1 (chymotrypsin)
 10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A peptidyl prolyl cis-trans isomerase (PPIase) was purified from a thermophilic methanogen, Methanococcus thermolithotrophicus. The PPIase activity was inhibited by FK506 but not by cyclosporine. The molecular mass of the purified enzyme was estimated to be 16 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 42 kDa by gel filtration. The enzyme was thermostable, with the half-lives of its activity at 90 and 100 degrees C being 90 and 30 min, respectively. The catalytic efficiencies (k(cat)/Km) measured at 15 degrees C for the peptidyl substrates, N-succinyl-Ala-Leu-Pro-Phe-p-nitroanilide and N-succinyl-Ala-Ala-Pro-Phe-p-nitroanilide, were 0.35 and 0.20 microM(-1) s(-1), respectively, in chymotrypsin-coupled assays. The purified enzyme was sensitive to FK506 and therefore was called MTFK (M. thermolithotrophicus FK506-binding protein). The MTFK gene (462 bp) was cloned from an M. thermolithotrophicus genomic library. The comparison of the amino acid sequence of MTFK with those of other FK506-binding PPIases revealed that MTFK has a 13-amino-acid insertion in the N-terminal region that is unique to thermophilic archaea. The relationship between the thermostable nature of MTFK and its structure is discussed.
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PMID:Biochemical and genetic characterization of an FK506-sensitive peptidyl prolyl cis-trans isomerase from a thermophilic archaeon, Methanococcus thermolithotrophicus. 944 May 28

The Schizosaccharomyces pombe gene, fkp39(+), encoding a homolog of FKBP(FK506 binding protein)-type peptidyl prolyl cis-trans isomerase (PPIase), was isolated and the primary structure was determined. This gene product (SpFkbp39p) showed PPIase enzymatic activity in a chymotrypsin-dependent enzyme assay involving recombinant SpFkbp39p. Comparison of the primary structures of the catalytic domains of FKBPs, including SpFkbp39p, revealed that FKBPs could be classified into four groups. This categorization corresponding to the known subcellular localization of the FKBPs, makes the prediction of the subcellular localization of FKBPs based on their primary structures feasible. SpFkbp39p was considered to be a member of the nuclear-type FKBP group from this relationship between primary structure and subcellular localization. An immunofluorescence assay against HA-epitope-tagged SpFkbp39p revealed that SpFkbp39p is localized to the nucleus, as predicted. Residues conserved in a "group-specific" manner in the catalytic domain were mapped to their corresponding three-dimensional positions; these "group-specific" residues were located in close proximity in distinct regions mostly on the protein surface, which implies the presence of "group-specific" regulatory functional regions. We also found that nuclear-type FKBPs, including SpFkbp39p, have two highly conserved domains other than catalytic ones, with further basic and acidic charged regions, especially in the case of nuclear-type FKBPs. This is the first report indicating that there is a rule for the relationship between the subcellular localization and structure of the catalytic domain of a FKBP.
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PMID:Relationship between the subcellular localization and structures of catalytic domains of FKBP-type PPIases. 1054 81