Document Detail

Addition of a methyl group changes both the catalytic velocity and thermostability of the neutral protease from Bacillus stearothermophilus.
MedLine Citation:
PMID:  2673840     Owner:  NLM     Status:  MEDLINE    
Specific activity was compared between wild-type (WT) neutral protease from Bacillus stearothermophilus and mutant protease (M1; Gly144 replaced by Ala144) with enhanced thermostability. When casein was used as a substrate, M1 showed 1.5-times higher specific activity than that of WT. In contrast, the specific activities of M1 for soluble reduced lysozyme and insulin B chain were lower than those of WT by 17.2 and 13.2%, respectively. After digestion of the insulin A chain by these enzymes, the peptide products were purified and the N-terminal amino acid sequences were determined. WT enzyme cleaved insulin A chain at three sites, whereas no digestion was observed with M1. Using Z-Gly-Leu-NH2 as a substrate, the kinetic parameters were determined. The Km values are nearly equal for both enzymes, whereas the kcat of M1 (240 min-1) was much smaller compared to the WT (830 min-1). The data indicate that the mutation (addition of a methyl group) exerts an effect by changing both the catalytic velocity and thermostability.
M Takagi; T Imanaka
Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  FEBS letters     Volume:  254     ISSN:  0014-5793     ISO Abbreviation:  FEBS Lett.     Publication Date:  1989 Aug 
Date Detail:
Created Date:  1989-10-23     Completed Date:  1989-10-23     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0155157     Medline TA:  FEBS Lett     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  43-6     Citation Subset:  IM    
Department of Fermentation Technology, Faculty of Engineering, Osaka University, Japan.
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MeSH Terms
Amino Acid Sequence
Binding Sites
Enzyme Stability
Geobacillus stearothermophilus / enzymology*
Hot Temperature
Insulin / analysis
Molecular Sequence Data
Peptide Fragments / isolation & purification
Peptide Hydrolases / genetics,  isolation & purification*
Thermolysin / analysis
Reg. No./Substance:
0/Peptide Fragments; 11061-68-0/Insulin; EC 3.4.-/Peptide Hydrolases; EC

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

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