Spectrophotometric Analysis of Multicomponent Systems Using Least Squares Method in Matrix Form.  Ergosterol Irradiation System

Sternberg, James C.; Stillo, H. S.; Schwendeman, R. H.

doi:10.1021/ac60157a025

Cited by 185 publications

(51 citation statements)

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“…where C is the unknown column matrix containing the concentration of each component, A is the column matrix containing the observed absorbances at each wavelength, and S is the known matrix containing the absorbance of each heme center at each wavelength (19,20). The known spectra of hemes a L and a 3 were taken from ref.…”

Section: Methodsmentioning

confidence: 99%

“…If the Q pool is not partitioned into two (a single pool is accessible to all enzymes), then adding NADH or succinate alone should reduce the whole population directly. Here, we monitored the redox status of complex III in SMPs by using a diode-array spectrometer to record spectra between 490 and 650 nm and the classical least squares method in matrix form (with known reference spectra) to deconvolute the difference spectra (i.e., the spectrum of interest minus the starting spectrum) into the contributions of the individual heme centers (19,20). SMPs were chosen for this experiment because membrane solutions with high enough concentrations for heme spectroscopy are more turbid, resulting in increased light scattering.…”

Section: Confirmation Of the Presence Of Supercomplexes In Submitochomentioning

confidence: 99%

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Kinetic evidence against partitioning of the ubiquinone pool and the catalytic relevance of respiratory-chain supercomplexes

Blaza

Serreli

Jones

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

163

126

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In mitochondria, four respiratory-chain complexes drive oxidative phosphorylation by sustaining a proton-motive force across the inner membrane that is used to synthesize ATP. The question of how the densely packed proteins of the inner membrane are organized to optimize structure and function has returned to prominence with the characterization of respiratory-chain supercomplexes. Supercomplexes are increasingly accepted structural entities, but their functional and catalytic advantages are disputed. Notably, substrate "channeling" between the enzymes in supercomplexes has been proposed to confer a kinetic advantage, relative to the rate provided by a freely accessible, common substrate pool. Here, we focus on the mitochondrial ubiquinone/ubiquinol pool. We formulate and test three conceptually simple predictions of the behavior of the mammalian respiratory chain that depend on whether channeling in supercomplexes is kinetically important, and on whether the ubiquinone pool is partitioned between pathways. Our spectroscopic and kinetic experiments demonstrate how the metabolic pathways for NADH and succinate oxidation communicate and catalyze via a single, universally accessible ubiquinone/ubiquinol pool that is not partitioned or channeled. We reevaluate the major piece of contrary evidence from flux control analysis and find that the conclusion of substrate channeling arises from the particular behavior of a single inhibitor; we explain why different inhibitors behave differently and show that a robust flux control analysis provides no evidence for channeling. Finally, we discuss how the formation of respiratory-chain supercomplexes may confer alternative advantages on energy-converting membranes.supercomplex | respirasome | mitochondria | respiratory chain | ubiquinone C ontemporary models for the organization of respiratorychain complexes in energy-transducing membranes range from the fluid model to the respirasome model. In the fluid model each complex is a free and independent entity, and substrates exchange freely between enzymes through common ubiquinone/ubiquinol (Q) and cytochrome c ox /c red (cyt c) pools (1-3). In the respirasome model the complexes are assembled into units that contain everything required for catalysis; substrates are channeled between enzymes within the respirasome, not exchanged with external pools (4, 5). Intermediate models, in which some enzymes are free and some assembled into multienzyme supercomplexes, or in which supercomplexes are assembled and disassembled in response to changing conditions, are increasingly considered a realistic combination of these two extremes (6).Structural evidence for respiratory-chain supercomplexes, initiated by observations by blue native PAGE analyses of mammalian mitochondria (4, 7), has culminated in electron microscopy data that revealed the arrangement of complexes I, III, and IV in a particular class of isolated supercomplex assembly (8, 9); respiratory-chain supercomplexes have also been observed (at lower resolution) in the membrane (10...

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Section: Methodsmentioning

confidence: 99%

Section: Confirmation Of the Presence Of Supercomplexes In Submitochomentioning

confidence: 99%

Kinetic evidence against partitioning of the ubiquinone pool and the catalytic relevance of respiratory-chain supercomplexes

Blaza

Serreli

Jones

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

163

126

View full text Add to dashboard Cite

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“…The value for 7-DHC was obtained from the designated vitamin D 2 equivalent, ergosterol (Sternberg, Stillo, & Schwendeman, 1960).…”

Section: Chemicalsmentioning

confidence: 99%

Investigation of the effect of UV-LED exposure conditions on the production of vitamin D in pig skin

et al. 2016

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Please cite this article as: Barnkob, L.L., Argyraki, A., Petersen, P.M., Jakobsen, J., Investigation of the effect of UV-LED exposure conditions on the production of vitamin D in pig skin, Food Chemistry (2016), doi: http:// dx.doi.org/10.1016/j.foodchem. 2016.05.155 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. implemented in existing food production facilities, without major modifications to the process or processing equipment, for bio-fortifying food products containing pork skin.3

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“…Multicomponent spectroscopic analysis of this sort has been used to analyze UV−vis absorbance data to quantify components of a mixture. 7,8 We recorded data for the overdetermined system having 76 signal vectors from measurements taken at 1 km and 500 m, and we knew the corresponding combinations for each. These data and combinations formed 3 × 76 matrices for the signal, S, and for the combinations, C. The matrix representation of the leastsquares analysis is as follows: (1) or = SR C (2) Multiplying both sides of eq 2 by the transpose of the signal matrix gives eq 3.…”

mentioning

confidence: 99%

Measuring Atomic Emission from Beacons for Long-Distance Chemical Signaling

et al. 2013

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ABSTRACT:In an effort to exploit chemistry for information science, we have constructed a system to send a message powered by a combustion reaction. Our system uses the thermal excitation of alkali metals to transmit an encoded signal over long distances. A message is transmitted by burning a methanol-soaked cotton string embedded with combinations of high, low, or zero levels of potassium, rubidium, and/or cesium ions. By measuring the intensities at the characteristic emission wavelengths of each metal in the near-infrared, 19 unique signals can be distinguished. We have built a custom telescope to detect these signals from 1 km away for nearly 10 min. The signal is isotropic, is self-powered, and has a low background. A potential application of this platform is for search and rescue signaling where another layer of information can be transmitted, in addition to the location of the beacon. This work, which seeks to encode and transmit information using chemistry instead of electronics, is part of the new field of "infochemistry".I n this paper, we describe a chemically powered light source that acts as a simple signaling beacon over long distances. The beacon is fueled by the combustion of methanol. Our atomic emission beacon is prepared by doping a cotton wick with metal salts; these salts are atomized during combustion and release thermally excited atomic emission. We detect the emission from metal atoms using a custom telescope equipped with bandpass filters and photodiodes (Figure 1). This work builds on our previous work using an "infofuse" to transmit messages encoded in flashes of atomic emission. 1−3 These efforts, along with previous work done using microfluidics 4 and bacteria-based encoded messages 5 aim to explore the nascent field of infochemistry.Infochemistry seeks to use chemical reactions to encode bits of information that can be used for communication or computation. This approach is a different way of thinking about information technology, which is now dominated by binary signals. By removing the assumption that communication must be electronic, one is free to imagine new chemicalbased platforms for information transmission. 6 These new systems can draw from all chemical and physical phenomena and need not rely solely on solid-state physics. We envision that these new platforms, such as the atomic emission beacon, will provide simple solutions for transmitting information in resource-limited environments, such as the scene of a disaster.The previously developed infofuse is capable of sending data at rates of several bits per second but suffers from one major drawback, the message is short-lived, usually only lasting a few seconds. 1,3 This brevity could make detection difficult if the detector is not aimed at the right place at exactly the right time. The atomic emission beacon seeks to remedy this issue and can transmit its message steadily for several minutes at the expense of lower information density. The atomic emission beacon Figure 1. Atomic emission beacon composed of a cotton wick d...

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Spectrophotometric Analysis of Multicomponent Systems Using Least Squares Method in Matrix Form. Ergosterol Irradiation System

Cited by 185 publications

References 11 publications

Kinetic evidence against partitioning of the ubiquinone pool and the catalytic relevance of respiratory-chain supercomplexes

Kinetic evidence against partitioning of the ubiquinone pool and the catalytic relevance of respiratory-chain supercomplexes

Investigation of the effect of UV-LED exposure conditions on the production of vitamin D in pig skin

Measuring Atomic Emission from Beacons for Long-Distance Chemical Signaling

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