ISSN:
1438-2199
Keywords:
Amino acids
;
Bacillus cereus
;
Sphingomyelinase
;
Pancreatic DNase I
;
Replacement of alanine
;
Replacement of histidine
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Chemical modifications suggested that acidic amino acids such as aspartic and glutamic acids are involved in the active sites ofBacillus cereus sphingomyelinase. Among aspartic acid residues in the conserved regions of this enzyme, Asp-126, Asp-156, Asp-233 and Asp-295 were converted to glycine by site-directed mutagenesis. According to prediction on structural similarity to pancreatic DNase I, His-151 and His-296 were also converted to alanine. The Asp and His mutants, D126G, D156G, D233G, D295G, H151A and H296A, were produced inBacillus brevis 47, a protein-hyperproducing strain. The catalytic activities of D295G, H151A and H296A were completely abolished, and sphingomyelin-hydrolyzing activity of D126G or D156G was reduced by more than 50%. The activity of D126G towardp-NPPC was comparable to that of the wild-type, while D156G catalyzed the hydrolysis of HNP andp-NPPC more efficiently than the wild-type. Hemolytic activities of the mutants were parallel to their sphingomyelin-hydrolyzing activities.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00805960
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