ISSN:
1432-072X
Keywords:
Key words K+-ATPase
;
Lactobacilli
;
Potassium pump
;
2
;
3-Butanedione
;
Enzyme-phosphate complex
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Lactobacillus helveticus ATCC 15009 (wild-type) membrane preparations hydrolyzed Mg2+-ATP as a function of K+ concentration (2–200 mM). Mg2+-ATP hydrolysis by L. helveticus membranes was strongly inhibited in the absence of exogenous K+, while it amounted to 6 nmol ATP hydrolyzed min–1 (mg membrane protein)–1 at 50 mM KCl (saturating conditions) and pH 7.2. The K+-dependent ATPase of L. helveticus displayed a relatively high affinity for potassium ions (K m = 800 μM) and was not affected by pretreatment of membranes with N,N’-dicyclohexylcarbodiimide. Membrane preparations were subjected to hypotonic shock to obtain a maximum yield of open profiles. The formation of a maximum level of enzyme-phosphate complex with a molecular mass of approximately 82 kDa was induced upon treatment of L. helveticus membrane preparations with low concentrations of [γ-32P]ATP in the presence of K+ and La3+ ions and was visualized by acidic SDS-PAGE. It was concluded that L. helveticus membranes contain an inwardly directed K+ pump whose presence is discussed in terms of its putative role in cytoplasmic pH regulation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002030050489
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