Document Detail


The role of glucosamine-6-phosphate deaminase at the early stages of Aspergillus niger growth in a high-citric-acid-yielding medium.
MedLine Citation:
PMID:  18214472     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Glucosamine-6-phosphate (GlcN6P) deaminase seems to be the main enzyme in Aspergillus niger cells responsible for rapid glucosamine accumulation during the early stages of growth in a high-citric-acid-yielding medium. By determining basic kinetic parameters on the isolated enzyme, a high affinity toward fructose-6-phosphate (Fru6P) was measured, while in the reverse direction the K(m) value for glucosamine-6-phosphate was lower than deaminases from other organisms measured so far. The enzyme characteristics of GlcN6P deaminase suggest it must compete with 6-phosphofructo-1-kinase (PFK1) for the common substrate-Fru6P in A. niger cells. Glucosamine accumulation seems therefore to remove an intermediate from the glycolytic flux, a situation which is reflected in slower citric acid accumulation and a specific growth rate after the germination of spores. When ammonium ions are depleted from the medium, one of the substrates for GlcN6P deaminase becomes limiting and Fru6P can be catabolised by PFK1 which enhances glycolytic flux. Other enzymatic features of GlcN6P deaminase such as pH optima for both aminating and deaminating reactions might play a significant role in rapid glucosamine accumulation during the early phase of fermentation and a slow consumption of aminosugar during the citric-acid-producing phase.
Authors:
Tina Solar; Janja Tursic; Matic Legisa
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-01-23
Journal Detail:
Title:  Applied microbiology and biotechnology     Volume:  78     ISSN:  0175-7598     ISO Abbreviation:  Appl. Microbiol. Biotechnol.     Publication Date:  2008 Mar 
Date Detail:
Created Date:  2008-03-11     Completed Date:  2008-06-17     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8406612     Medline TA:  Appl Microbiol Biotechnol     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  613-9     Citation Subset:  IM    
Affiliation:
National Institute of Chemistry, Hajdrihova 19, 1001 Ljubljana, Slovenia.
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MeSH Terms
Descriptor/Qualifier:
Aldose-Ketose Isomerases / analysis,  isolation & purification,  metabolism*
Aspergillus niger / enzymology*,  growth & development
Citric Acid / metabolism*
Culture Media / chemistry*
Fermentation
Fructosephosphates / metabolism
Fungal Proteins / analysis,  isolation & purification,  metabolism
Kinetics
Quaternary Ammonium Compounds / analysis,  metabolism
Chemical
Reg. No./Substance:
0/Culture Media; 0/Fructosephosphates; 0/Fungal Proteins; 0/Quaternary Ammonium Compounds; 6814-87-5/fructose-6-phosphate; 77-92-9/Citric Acid; EC 3.5.99.6/glucosamine-6-phosphate isomerase; EC 5.3.1/Aldose-Ketose Isomerases

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


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