Questions tagged [enzyme-kinetics]

Enzyme kinetics is the study of the rates of enzyme-catalysed reactions

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Different enzymes catalyzing the same reaction but in opposite directions

Nelson, D. L., & Cox, M. M. (2017). Principles of Biochemistry 7e. W. H. Freeman. 13.3: Phosphoryl Group Transfers and ATP: Inorganic Polyphosphate Is a Potential Phosphoryl Group Donor. (This ...
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Relationship between Km and IC50 in cellular uptake assay

I'm going to describe the scenario in general terms at first so as to try and get to the theoretical content of the problem, but I'll post a link to the paper which got me thinking about it at the ...
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Difference between IC50 and Michaelis-Menten constant

I am new to biology, and getting to know the term IC50, I found that there is a connection between IC50 and Michaelis-Menten constant by the Cheng-Prusoff equation $K_{i}=\frac{\mathrm{IC}_{50}}{1+\...
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Does it make sense to express membrane transporters as concentration?

Let's assume a situation where a molecule, S, is transported out of the cell by membrane transporter T. For simplicity we do not consider any other synthesis or production processes. Furthermore, we ...
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Which enzyme is Nick Lane referring to?

In Life Ascending the author, Nick Lane, refers to an enzyme in his introduction: '' It concerns an enzyme (a protein that catalyses a chemical reaction) that is so central to life that it is found ...
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How to convert between Kunitz units and Enzymatic units?

I've googled around and there has been the common answer of 1.5 U = 1 Kunitz Unit, but none of those answers have come from a reputable source, so I am really doubtful. :( The enzyme I use comes in ...
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What is the concentration/molecules per cell of iodothyronine deiodinase in a cell?

I'm trying to parameterize an in silico model and need the approximate concentration (M), or molecules per cell, of iodothyronine deiodinase type II (D2) enzyme in a human cell, ideally a glial cell. ...
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Measuring Enzyme Kinetic constants

Is it possible to experimentally determine $k_1$ and $k_{-1}$ of the Michaelis Menten model: $\ce{E + S <-->[k_1][k_{-1}] ES ->[k_{cat}] E + P}$, or their ratio?
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Specific activity vs turnover number of enzymes in BRENDA

From my understanding, the specific activity (A, units: umol/min/mg protein) can be derived from the turnover number (k, units: 1/seg) and the molar mass of an enzyme (MW, units: g/mol): A = k / MW / ...
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Convert flux value in nmol/min/mg protein to nmol/min/cell?

This is a question about unit conversion. I found an experimental measurement of the saturation uptake of glucose in yeast: $$V_\textrm{max} \approx 650 \textrm{nmol}/\textrm{min}/\textrm{mg protein}$$...
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How to theoretically calculate amount of product in first-order reaction?

I was wondering if it was possible to calculate the amount of product theoretically produced from in vivo (human) values to determine if that's the only enzyme causing the increase in amount of ...
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How to predict enzyme activity computationally

if I have an enzyme and its corresponding substrate, are there computational methods that I can use to predict its enzymatic activities? I understand that we can determine its activity using various ...
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Determining the Value of Inhibition constant

I am trying to understand how the inhibition constant is calculated for competitive inhibition. $\frac{K^{app}}{V^{app}} = \frac{1+I/K_i}{V/K_m}$. But often in secondary plots, $\frac{K^{app}}{V^{...
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Assay for Glycosyltransferase

I want to do an assay to see, if an ordered enzyme is active or not. It's a glucosyltransferase from S. mutans which hydrolyses sucrose into fructose and glucose. It then connects the glucose-monomers ...
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Glucose Oxidase, Condition to be Active?

I most recently was reading/watching information on honeys antibatical and antimicrobial properties. The enzyme Glucose Oxidase came up often as a main antimicrobial, yet it is inactive in honey. ...
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Increasing enzyme concentration does not increase product formation

I am cutting DNA strand 40 nt long with enzyme with single cleavage site in DNA. At the lowest concentration of enzyme I use, 50% of the substrate is cleaved, however, increasing enzyme concentration ...
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Does Invertase catalyse the hydrolysis of other sugars other than sucrose?

I recently did a lab where we tested out the substrate specificity of Invertase on different types of sugars such as sugar alcohols and disaccharides, measured by the absorbance of red using a ...
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Kinases that are ATP-sensitive at physiological conditions?

Phosphorylation is an ATP-dependent process performed by kinases. At physiological conditions it is generally assumed that ATP concentration is high enough so that ATP is not a limiting factor. ...
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