Anionic stimulation of the hill reaction in isolated chloroplasts

Gorham, Paul R.; Clendenning, K. A.

doi:10.1016/0003-9861(52)90179-3

Cited by 52 publications

(10 citation statements)

References 21 publications

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“…Figure 1 also provides evidence that other anions could replace Cl-as protecting agents with an order of effectiveness given by the sequence Cl-m Br-> N03 > F > C104 . Qualitatively, the ranking of the anions was identical to that of their ability to support the mechanism of water oxidation (18,24,28), with one notable exception: F-had some protective ability but is known to be an ineffective substitute of Cl-as a cofactor of the water oxidase (16,18,24,28).…”

Section: Methodsmentioning

confidence: 80%

“…Our data suggest that the activating function of monovalent anions in the water oxidizing mechanism and their influence on the binding of the 17 and 23 kD extrinsic polypeptides may have a common mechanistic basis. This implies a structural role of Cl-as it was proposed 35 years ago by Gorham and Clendenning (16) when they explained the function ofCl-in the photosynthetic electron transport chain by its ability to provide a "favorable electrokinetic potential at (the involved) colloidal surfaces. "…”

mentioning

confidence: 83%

“…It is known that anion-regulated enzymes quite generally respond to an addition of the anions with an alkaline-shift of the pH profile of their activity. This is also the case for the water oxidase (16) and for the dissociation of the 23 kD polypeptide (22). Massey (cited in Ref.…”

Section: Discussionmentioning

confidence: 99%

“…water oxidizing complex (35), the unique pH dependence of Clbinding (21), the complex pattern of 35Cl-NMR line broadening (2,10), and the ability of other monovalent anions such as NO3 to serve as rather efficient substitutes for Cl- (16,18,24,28).…”

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confidence: 99%

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Structural Effects of Cl⁻ and Other Anions on the Water Oxidizing Complex of Chloroplast Photosystem II

Homann¹

1988

Plant Physiol.

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To further our understanding of the role of Cl-and certain other monovalent anions in the oxygen evolving photosystem II of chloroplasts, dissociating and stabilizing anion effects on the extrinsic 17 and 23 kilodalton polypeptides of the photosynthetic water oxidizing complex were investigated. It was found that (a) the dissociation of the two polypeptides in Cl-free media of pH -7 was enhanced by millimolar concentrations of the divalent anion S042-and also by divalent cations like Mg2" and Ca2"; (b) the dissociation was opposed by relatively low concentrations of monovalent anions with an order of effectiveness Cl-= Br-> N03-> F > C104-; (c) at molar concentrations, S042-stabilized the binding of the 23 kilodalton polypeptide, while Cl-and Br-became dissociating agents, in agreement with studies by Blough and Sauer (1984 Biochim Biophys Acta 767: 377-381); (d) the binding of the polypeptides was strengthened at room temperature relative to 0°C, indicating an involvement of hydrophobic forces. It is suggested that a specific binding of Cl-, or certain substitutes, organizes the protein surfaces and/or the adjacent water layers in the water oxidizing complex in a way that not only stabilizes its assembly, but is essential for the catalytic mechanism as well. Binding of, or charge screening by, divalent ions interferes with this process. At high salt concentrations, all these effects are overridden by "lyotropic" actions of the solutes that affect the integrity of the water oxidizing protein complex by stabilizing or disrupting critical hydrophobic domains.Removal of Cl-from PSII of chloroplast thylakoids causes an aberration and interruption of the normal progress of charge accumulation in and perhaps around the Mn-cluster ofthe water oxidizing complex (for reviews, see Refs. 15, 17, and 21). However, the exact function of Cl-is not understood. Sandusky and Yocum (33) have proposed that an essential step in the mechanism of water oxidation is a ligation of Cl-to the Mn-cluster itself. This concept was developed on the basis of their finding that Cl-, in a competitive fashion, protected the water oxidizing mechanism from the inhibitory action of NH3 and various amines, the action of which was attributed to a binding to the oxidant storing Mn-complex. Taking an alternative view, Govindjee's group (8, 17) and we (19,21) have proposed various mechanistic versions for a role of protein-bound Cl-in the deprotonation events accompanying water oxidation. Such an indirect participation of the anion in the catalytic process was postulated because of precedents in other enzyme systems (8,14) and to account for the reported need of more than one Cl-per ' Supported by grant DMB 8304416 from the National Science Foundation.water oxidizing complex (35), the unique pH dependence of Clbinding (21), the complex pattern of 35Cl-NMR line broadening (2, 10), and the ability of other monovalent anions such as NO3 to serve as rather efficient substitutes for 18,24,28).The Cl-relations of PSII are known to be greatly influenc...

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Section: Methodsmentioning

confidence: 80%

mentioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Structural Effects of Cl⁻ and Other Anions on the Water Oxidizing Complex of Chloroplast Photosystem II

Homann¹

1988

Plant Physiol.

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“…Gorham and Clendenning (18) have attributed its effect to some physical effect on the chloroplasts, comparable to the effect on amylase and salt respiration of roots. The action of chloride and Carbowax on the Hill reaction of higher plant chloroplasts seems to be similar, since they both permit a more linear time course (18). Chloride is no substitute for Carbowax, however, as the effect of the latter is shown in the presence of the former.…”

Section: Discussionmentioning

confidence: 86%

The Physical Environment of Chloroplasts as Related to their Morphology and Activity in Vitro

McClendon

1954

Plant Physiol.

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Chloride and calcium in Photosystem II: from effects to enigma

Homann

Discoveries in Photosynthesis

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Anionic stimulation of the hill reaction in isolated chloroplasts

Cited by 52 publications

References 21 publications

Structural Effects of Cl⁻ and Other Anions on the Water Oxidizing Complex of Chloroplast Photosystem II

Structural Effects of Cl⁻ and Other Anions on the Water Oxidizing Complex of Chloroplast Photosystem II

The Physical Environment of Chloroplasts as Related to their Morphology and Activity in Vitro

Chloride and calcium in Photosystem II: from effects to enigma

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Anionic stimulation of the hill reaction in isolated chloroplasts

Cited by 52 publications

References 21 publications

Structural Effects of Cl− and Other Anions on the Water Oxidizing Complex of Chloroplast Photosystem II

Structural Effects of Cl− and Other Anions on the Water Oxidizing Complex of Chloroplast Photosystem II

The Physical Environment of Chloroplasts as Related to their Morphology and Activity in Vitro

Chloride and calcium in Photosystem II: from effects to enigma

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Product

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Structural Effects of Cl⁻ and Other Anions on the Water Oxidizing Complex of Chloroplast Photosystem II

Structural Effects of Cl⁻ and Other Anions on the Water Oxidizing Complex of Chloroplast Photosystem II