ISSN:
1432-072X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary 1. The “biosynthetic” l-threonine (deaminating) dehydratase o-7 marine planktonic species from 5 classes of algae showed several degrees of activation from monovalent inorganic cations. The activation was generally the strongest (3 to 5-fold) with K+ and NH4 +, and the weakest (1 to 2-fold) with Na+ and Tl+, whilst Li+, Rb+ and Cs+ showed intermediate orders varying with algal species. One blue-green alga was exceptional in showing strongest stimulation (5-fold) from Li+ and more pronounced activation from Na+ than Cs+ whilst a green alga showed another type of response with the least effect from Li+ and markedly greater activation from Rb+ than NH4 +. 2. The cation activation showed (i) “hyperbolic” kinetic response to ion concentration, and (ii) high specificity for monovalent inorganic cations, with indications of a coenzyme type of role for the alkalimetal type of ions. 3. Organic cations were inert and the divalent cations Mg2+, Ca2+, Zn2+, Cu2+ were either inhibitory or without effect. 4. Among the anions tested, chloride, bromide, fluoride, bicarbonate showed no effect, iodide, nitrate, chlorate were inhibitory, whilst phosphate and sulfate were slightly stimulatory. 5. It was concluded that the algal enzymes may have an absolute K+ or NH4 + requirement for in vivo expression of activity.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00549272
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