Effects of K+ on the catalytic and regulatory properties of homoserine dehydrogenase of Pseudomonas fluorescens

Bothwell, Mark A.; Datta, P.K.

doi:10.1016/0005-2744(71)90026-x

Cited by 8 publications

(2 citation statements)

References 17 publications

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“…There are other reports of K+-activated enzymes that recover activity only slowly on returning to potassium salts after prolonged dialysis against water ofnon-activation ions (Green, 1964;Wilson et al, 1967;Wampler & Westhead, 1968;Bothwell & Datta, 1971).…”

Section: Below)mentioning

confidence: 99%

Kinetic and spectroscopic evidence of cation-induced conformation changes in yeast K+-activated aldehyde dehydrogenase

Betts¹,

Poole²,

Springham³

et al. 1979

Biochemical Journal

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The activity, stability and spectroscopic properties of yeast K+ -activated aldehyde dehydrogenase were measured at various times after removal from, and after returning to a solution containing K+. Enzyme activity is rapidly lost on removal of most of the K+ and rapidly regained if K+ is replaced immediately. These activity changes are slower than likely rates of K+ dissociation and association. These rapid changes in concentration result in altered enzyme stability with enzyme in K+ the more stable. U.v. difference spectra are produced whenever enzyme in an activating environment (K+ or Tl+) is compared with enzyme in a non-activating environment (Tris+ or Li+). These spectral changes occur within 10s. The saturation characteristics with K+ are hyperbolic for all three phenomena of activation, stabilization and spectral change, with estimated apparent dissociation constants (Ks) for K+ of 7.5 mM, 5.5 mM and 6 mM respectively. Continued incubation of enzyme in the absence of K+ results in the accumulation of an enzyme form that re-activates only slowly on replacing K+. Stability characteristics in various concentrations of K+ over equivalent time scales are consistent with the existence of additional conformations. Spectroscopic evidence also indicates such additional slow conformation changes. Results have been interpreted in terms of two separate conformation transitions induced or stabilized by K+.

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Section: Below)mentioning

confidence: 99%

Kinetic and spectroscopic evidence of cation-induced conformation changes in yeast K+-activated aldehyde dehydrogenase

Betts¹,

Poole²,

Springham³

et al. 1979

Biochemical Journal

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show abstract

“…However, K+ is required only for stabilization of certain microbial enzymes (2,5). The tetrameric, threoninesensitive aspartokinase-homoserine dehydrogenase of Escherichia coli K-12 is stabilized by potassium ions and is activated by K+ and NH4+ (17), but activation is antagonized by Na+ (21).…”

Section: Column 3)mentioning

confidence: 99%

Changes in Enzyme Regulation during Growth of Maize

Dicamelli

Bryan²

1975

Plant Physiol.

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The relative contribution of each of several forms of homoserine dehydrogenase (EC 1.1.1.3) to the total enzyme population in etiolated shoots and in roots of Zea mays L. var. earliking was examined by the use of gel filtration chromatography and disc gel electrophoresis. In enzyme preparations derived from shoots of seedlings grown for 72, 120, or 168 hours, two molecular forms, II and III, which have the same apparent molecular weight but differ in net charge, contributed 75 to 80 % of the total enzyme activity. A lower molecular weight species, form I, contributed 20 to 25 % of the activity from 72-hour shoots, but was found to decrease concomitantly with a proportional increase in activity contributed by aggregated enzyme form (s) during shoot development. Form I contributed a comparatively larger fraction of the total enzyme activitv in preparations of roots of 72-hour seedlings.The characteristic enzyme activity of different tissues was found to be the result of variations in both the amount and the properties of individual forms. Form I was consistently insensitive to inhibition by the feed-back modifier, L-threonine, but evidence is presented which indicates that the regulatory properties of form II and/or form III are systematically altered during shoot growth. The activity of the enzyme forms was also differentially stimulated by monovalent cations, K+ being the most effective activator; in all cases the potential for activation was correlated with the potential for inhibition. In contrast to these differences among the forms of the maize enzyme, all forms were shown to share a number of common characteristics. Potential factors which could influence the growth-associated changes in homoserine dehydrogenase are discussed briefly.

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Alkali Metal Ion Transport and Biochemical Activity

Chock¹,

Titus²

1973

Progress in Inorganic Chemistry

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Effects of K+ on the catalytic and regulatory properties of homoserine dehydrogenase of Pseudomonas fluorescens

Cited by 8 publications

References 17 publications

Kinetic and spectroscopic evidence of cation-induced conformation changes in yeast K+-activated aldehyde dehydrogenase

Kinetic and spectroscopic evidence of cation-induced conformation changes in yeast K+-activated aldehyde dehydrogenase

Changes in Enzyme Regulation during Growth of Maize

Alkali Metal Ion Transport and Biochemical Activity

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