A comment on Warburg’s early understanding of biocatalysis

Höxtermann, Ekkehard

doi:10.1007/s11120-007-9164-2

Cited by 8 publications

(4 citation statements)

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“…It is also clear that CO 2 is included in the reaction sequence only as a catalyst. A more detailed consideration of the presented reaction scheme could show an analogy between the complex ChlZH-CO 3 -and the so-called "photolyte" component of the celebrated Otto Warburg (Warburg 1920; see also Höxtermann, 2007;Nickelsen, 2007). According to Warburg et al (1969) the binding of carbonic acid occurs in two consecutive reactions, both of which require the energy provided by oxygen respiration.…”

Section: Variation In the Number Of Effectively Functioning Oxygen-evmentioning

confidence: 99%

Is the Concept of Photosynthetic Units Verified?

Zeinalov

2009

Zeitschrift Für Naturforschung C

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Fundamental ResultsIn the beginning of the 4th decade of the last century, during the investigations of the photosynthetic light reactions, several important results were obtained, whose explanation led to significant complications and, thus, to the postulation of the fi rst fundamental hypothesis, i.e. the concept of the photosynthetic unit (PSU) (Emerson and Arnold, 1932a, b;Gaffron and Wohl, 1936). According to this concept, in all photosynthetic systems (photosynthetic bacteria, green unicellular algae, higher plants etc.) the light-absorbing pigment molecules are divided into two groups. Only one highly specialized pigment molecule (named reaction centre) present among dozens of bacteria and among hundreds of green photosynthetic systems could carry out the photochemical (charge separation) reaction. The essential part of the pigment molecules absorbs light quanta only and transfers the light energy to the reaction centres.In 1932, Emerson and Arnold applied for the fi rst time fl ash-induced experiments in photosynthesis, using the manometric equipment introduced by Warburg (1920) and saturating fl ashing light, obtained by the discharge of an 1-or 0.5-μF condenser, charged to about 3000 V, through a neon tube.The fundamental results from the fl ash experiments of Emerson and Arnold were as follows:1. The time required for one unit in the photosynthetic machinery to complete the cycle of photochemical and Blackman (dark) reactions was about 0.02 s at 25 ºC.2. The average fl ash yields were maximal when the spacing (dark period) between the fl ashes was about 0.02 s (20 ms).3. The dependence of the quantity of the oxygen molecules (in mol) evolved after one saturated fl ash on the quantity of the chlorophyll (Chl) molecules in the Chlorella cell suspension was linear with a slope of about 1 O 2 : 2480 chlorophyll molecules, thus suggesting that after every fl ash one oxygen molecule was produced by 2480 chlorophyll molecules. Consequently, in Chlorella pyrenoidosa suspensions with different chlorophyll concentrations approx. 4 · 10 -4 M oxygen was evolved from 1 mol chlorophyll after every fl ash. 4. A good coincidence has been established between the experimentally obtained maximal rate of oxygen evolution, P max , under continuous saturated irradiation and the theoretically calculated maximal rate, P = N/τ, where N is the estimated number of the oxygen-producing units and τ is the turnover time from fl ash light experiments. This correlation has shown that under continuous saturated irradiation the number of effectively operating oxygen-evolving centres was approx. 1:600 of the number of the chlorophyll molecules in the investigated suspension, as estimated in the fl ash experiments.The cornerstones of the fi rst fundamental concept of photosynthetic machinery, i.e. the concept of photosynthetic units, are reconsidered and a new logically and experimentally well sustained interpretation of the crucial observations of this hypothesis is presented. The results obtained lead to the conclusion that under low ...

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Section: Variation In the Number Of Effectively Functioning Oxygen-evmentioning

confidence: 99%

Is the Concept of Photosynthetic Units Verified?

Zeinalov

2009

Zeitschrift Für Naturforschung C

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“…Warburg had clearly not yet arrived at his final view on photosynthesis, as prominently expressed, for example, in Warburg et al 1969, in which he spoke of the complex of chlorophyll bound to carbonic acid as being ''the photolyte'' (which, of course, as we know today, is a purely speculative concept without any material correlate; see also Höxtermann and Sucker 1989, pp. 94-99; also see Höxtermann 2007).…”

Section: Photosynthesis Framed As a Photolysismentioning

confidence: 99%

“…This corresponds exactly to Warburg's interpretation of the process of cell respiration, arrived at after researching the subject from 1908 to 1914: it is a surface-dependent series of reactions that requires the participation of iron (Warburg 1914;Höxtermann 2001, pp. 265-268;Kohler 1973; also see Höxtermann 2007). Warburg postulated that, in the case of photosynthesis, three different classes of reaction were involved:…”

Section: Surveymentioning

confidence: 99%

Otto Warburg’s first approach to photosynthesis

Nickelsen

2007

Photosynth Res

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In the field of photosynthesis research, Otto Warburg (1883Warburg ( -1970 is predominantly known for the role he played in the controversy that began in the late 1930s regarding the maximum quantum yield of photosynthesis, even though by that time he had already been working on the topic for more than a decade. One of Warburg's first contributions on the subject, which dates from around 1920, is his proposal for a detailed model of photosynthesis, which he never completely abandoned, despite later overwhelming evidence in favor of alternatives. This paper presents a textual and graphical reconstruction of Warburg's model and of his argument for its validity. Neither has received much attention in the history of science, even though the model was certainly one of the most plausible explanations of the period and therefore could not be so easily discredited.

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“…Scientists knew that cells transform substrates into other molecules in some manner, but the nature of such transformations was obscure, as was the question of whether any chemical transformations were universal among cells. Otto Warburg helped to unravel a good many of the chemical transformations germane to the reactions that keep cells alive [6,7]. Today, we know a great deal about how cells transform molecules during the process of growth (physiology, the chemical reactions of growth) and how the information that directs the synthesis of a new cell is stored and retrieved, but the origins problem of how such reactions started remains, although some newer findings do harbor hints of progress in that they identify a distinct chemical connection between geochemical reactions and what might have been the first biochemical reactions [8,9].…”

Section: Introductionmentioning

confidence: 99%

To What Inanimate Matter Are We Most Closely Related and Does the Origin of Life Harbor Meaning?

2021

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The question concerning the meaning of life is important, but it immediately confronts the present authors with insurmountable obstacles from a philosophical standpoint, as it would require us to define not only what we hold to be life, but what we hold to be meaning in addition, requiring us to do both in a properly researched context. We unconditionally surrender to that challenge. Instead, we offer a vernacular, armchair approach to life’s origin and meaning, with some layman’s thoughts on the meaning of origins as viewed from the biologist’s standpoint. One can observe that biologists generally approach the concept of biological meaning in the context of evolution. This is the basis for the broad resonance behind Dobzhansky’s appraisal that “Nothing in biology makes sense except in the light of evolution”. Biologists try to understand living things in the historical context of how they arose, without giving much thought to the definition of what life or living things are, which for a biologist is usually not an interesting question in the practical context of daily dealings with organisms. Do humans generally understand life’s meaning in the context of history? If we consider the problem of life’s origin, the question of what constitutes a living thing becomes somewhat more acute for the biologist, though not more answerable, because it is inescapable that there was a time when there were no organisms on Earth, followed by a time when there were, the latter time having persisted in continuity to the present. This raises the question of where, in that transition, chemicals on Earth became alive, requiring, in turn, a set of premises for how life arose in order to conceptualize the problem in relation to organisms we know today, including ourselves, which brings us to the point of this paper: In the same way that cultural narratives for origins always start with a setting, scientific narratives for origins also always start with a setting, a place on Earth or elsewhere where we can imagine what happened for the sake of structuring both the problem and the narrative for its solution. This raises the question of whether scientific origins settings convey meaning to humans in that they suggest to us from what kind of place and what kinds of chemicals we are descended, that is, to which inanimate things we are most closely related.

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A comment on Warburg’s early understanding of biocatalysis

Cited by 8 publications

References 33 publications

Is the Concept of Photosynthetic Units Verified?

Is the Concept of Photosynthetic Units Verified?

Otto Warburg’s first approach to photosynthesis

To What Inanimate Matter Are We Most Closely Related and Does the Origin of Life Harbor Meaning?

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