These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Significance of Tyr302, His235 and Asp194 in the α-amylase from Bacillus licheniformis.
    Author: Qin Y, Fang Z, Pan F, Zhao Y, Li H, Wu H, Meng X.
    Journal: Biotechnol Lett; 2012 May; 34(5):895-9. PubMed ID: 22261861.
    Abstract:
    The calcium-binding residues, Tyr302 and His235, and the sodium-binding residue, Asp194, on the activity of Bacillus licheniformis α-amylase were investigated using site-directed mutagenesis. Tyr302 and His235 were replaced by Asn and Asp, respectively, to produce the mutants Y302N and H235D; Asp194 was replaced by Ala to produce D194A. The mutant amylases were purified to homogeneity; each was ~53 kDa. The specific activity of the D194A was 236 U mg(-1), lower than the specific activity of the wild-type enzyme by 55%. No significant changes of thermostability, optimum temperature, and optimum pH level were observed in D194A. Mutant amylases with H235D and Y302N significantly improved their specific activity by 43% (754 U mg(-1)) and 7% (563 U mg(-1)), respectively, compared with the wild-type enzyme. H235D substitution decreased its optimum pH by approx. 0.5-1 pH unit.
    [Abstract] [Full Text] [Related] [New Search]