Nonlinear least-squares data fitting in Excel spreadsheets

Kemmer, Gerdi Christine; Keller, Sandro

doi:10.1038/nprot.2009.182

Cited by 464 publications

(393 citation statements)

References 60 publications

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“…Fitting and statistical analysis of the experimental results to the proposed equations were carried out in four phases: 1) Coefficients determination: Parametric estimates were obtained by minimization of the sum of the quadratic differences between observed and model-predicted values, using the nonlinear least-squares (quasi-Newton) method provided by the macro Solver in Microsoft Excel 2003 (Kemmer and Keller, 2010), which allows a quick testing of a hypotheses and its consequences .…”

Section: Numerical Methods and Statistical Analysismentioning

confidence: 99%

Optimization of microwave-assisted extraction of hydrophilic and lipophilic antioxidants from a surplus tomato crop by response surface methodology

Pinela

Prieto

Barreiro

et al. 2016

Food and Bioproducts Processing

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Section: Numerical Methods and Statistical Analysismentioning

confidence: 99%

Optimization of microwave-assisted extraction of hydrophilic and lipophilic antioxidants from a surplus tomato crop by response surface methodology

Pinela

Prieto

Barreiro

et al. 2016

Food and Bioproducts Processing

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“…• Coefficients estimation was obtained by minimization the sum of quadratic differences between the observed and model-predicted values, using the nonlinear least-squares (quasi-Newton) method provided by the macro Solver in Microsoft Excel (Kemmer and Keller, 2010). …”

Section: Fitting Procedures and Statistical Analysismentioning

confidence: 99%

Modern extraction techniques optimized to extract betacyanins from Gomphrena globosa L.

Roriz

Barros

Prieto

et al. 2017

Industrial Crops and Products

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A B S T R A C TGomphrena globosa L. is a source of betacyanins, molecules with high colorant power. In order to replace conventional extraction techniques, microwave (MAE) and ultrasound assisted extraction (UAE) processes were optimized by the response surface methodology (RSM) to maximize the recovery of betacyanins from G. globosa. A five-level full factorial design of 24 combinations and 4 replicates was implemented for MAE and UAE. The optimum processing conditions for MAE (t = 8 min; T = 60°C; Et = 0%; and S/L = 5 g/L) conducted to an extraction yield of 39.6 ± 1.8 mg/g dry weight, while for UAE (t = 22 min; P = 500%; Et = 0%; and S/ L = 5 g/L) a value of 46.9 ± 4.8 mg/g was achieved, validating the UAE more suitable to obtain the target compounds. This technique can provide extracts rich in betacyanins and with high potential to be used as natural colorants.

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“…Each assay was performed in triplicate. The apparent kinetic constants were calculated by fitting the initial velocity data to the Henri-Michaelis-Menten's equation using Solver function in the Microsoft excel (85).…”

Section: Kinetic Assay Of F 420 H 2 -Dependent Trx Reductase (Dftr)-mentioning

confidence: 99%

A Novel F420-dependent Thioredoxin Reductase Gated by Low Potential FAD

Susanti¹,

Loganathan²,

Mukhopadhyay

2016

Journal of Biological Chemistry

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A recent report suggested that the thioredoxin-dependent metabolic regulation, which is widespread in all domains of life, existed in methanogenic archaea about 3.5 billion years ago. We now show that the respective electron delivery enzyme (thioredoxin reductase, TrxR), although structurally similar to flavincontaining NADPH-dependent TrxRs (NTR), lacked an NADPH-binding site and was dependent on reduced coenzyme F 420 (F 420 H 2 ), a stronger reductant with a mid-point redox potential (E 0 ) of ؊360 mV; E 0 of NAD(P)H is ؊320 mV. Because F 420 is a deazaflavin, this enzyme was named deazaflavin-dependent flavin-containing thioredoxin reductase (DFTR). It transferred electrons from F 420 H 2 to thioredoxin via proteinbound flavin; K m values for thioredoxin and F 420 H 2 were 6.3 and 28.6 M, respectively. The E 0 of DFTR-bound flavin was approximately ؊389 mV, making electron transfer from NAD(P)H or F 420 H 2 to flavin endergonic. However, under high partial pressures of hydrogen prevailing on early Earth and present day deep-sea volcanoes, the potential for the F 420 /F 420 H 2 pair could be as low as ؊425 mV, making DFTR efficient. The presence of DFTR exclusively in ancient methanogens and mostly in the early Earth environment of deep-sea volcanoes and DFTR's characteristics suggest that the enzyme developed on early Earth and gave rise to NTR. A phylogenetic analysis revealed six more novel-type TrxR groups and suggested that the broader flavin-containing disulfide oxidoreductase family is more diverse than previously considered. The unprecedented structural similarities between an F 420 -dependent enzyme (DFTR) and an NADPH-dependent enzyme (NTR) brought new thoughts to investigations on F 420 systems involved in microbial pathogenesis and antibiotic production.

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Nonlinear least-squares data fitting in Excel spreadsheets

Cited by 464 publications

References 60 publications

Optimization of microwave-assisted extraction of hydrophilic and lipophilic antioxidants from a surplus tomato crop by response surface methodology

Optimization of microwave-assisted extraction of hydrophilic and lipophilic antioxidants from a surplus tomato crop by response surface methodology

Modern extraction techniques optimized to extract betacyanins from Gomphrena globosa L.

A Novel F420-dependent Thioredoxin Reductase Gated by Low Potential FAD

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