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: Directed evolution of Penicillium janczewskii zalesk α-galactosidase toward enhanced activity and expression in Pichia pastoris.
    Author: Chen Y, Zhang B, Pei H, Lv J, Yang W, Cao Y, Dong B.
    Journal: Appl Biochem Biotechnol; 2012 Oct; 168(3):638-50. PubMed ID: 22833403.
    Abstract:
    In this study, the activity of an α-galactosidase obtained from Penicillium janczewskii zalesk was improved via modifying its gene by error-prone PCR and DNA shuffling. The mutated DNA was ligated to pBGP1, an autonomous-replicating vector, which was subsequently transformed into Pichia pastoris X-33. The expressed enzyme activities were measured after single colonies were cultured in yeast-peptone-dextrose medium in deep-well plates. After two rounds of screening, two mutants with higher activity were obtained. By PCR analysis, four mutation sites (S167G, P455L, N637S, and P490L/P490H) were found in these two variants (mutant-59 and mutant-8). Mutant-59 showed the highest activity at pH 5.0 and 40 °C with an increased V(max) value of 769 μmol/min and the specific activity of 667 U/mg against p-nitrophenyl α-D-galactopyranoside. The two mutant enzymes also showed similar resistance to the metal ions of Cu(2+), Fe(2+), and Zn(2+). In a 10-L fermenter, the supernatant enzyme activity reached the maximum of 550.2 U/mL upon the methanol induction for 96 h. This fermentation activity of the mutant was improved approximately two more folds than the wild type α-galactosidase. This mutant of α-galactosidase is prospective in feed manufacturing as feed additives to improve nutrient digestibility in monogastric animals.
    [Abstract] [Full Text] [Related] [New Search]