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Questions tagged [enzymes]

Enzymes are globular proteins that catalyse a biochemical reaction, increasing the overall rate by reducing activation energy. Most chemical reactions in a cell need enzymes in order to occur at rates sufficient to sustain life.

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Reversal of reactions and enzyme catalysis

Enzymes increase the rate of a reaction. They cannot affect the rate constant, thus the rate of both the backwards and forwards reaction is increased. This means the same enzyme catalyses the forwards ...
User51's user avatar
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Function of coenzymes: do they act as substrate shuttles?

My biochemistry textbook, "Harper's Illustrated Biochemistry", states: Coenzymes serve as recyclable shuttles that transport many substrates from one point within the cell to another. The ...
Lakshya Kumar Singh's user avatar
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Can humans metabolize D-malate?

Only the L-isomer is produced naturally, while racemic mixtures are produced synthetically and used commercially as food additives and energy supplements. So what happens when we consume D-malate? ...
ManRow's user avatar
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Competitive inhibition - Similarity between substrate and inhibitor

I have this question - Q. Competitive inhibitor which binds to the enzyme (a) has structural similarity with the product (b) is chemically similar to the substrate (c) has physical structure similar ...
Apogee Point's user avatar
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What is the enzyme production rate of a single E. Coli bacterium?

Suppose an E.Coli bacterium intakes a plasmid which encodes for an enzyme, if the promoter strength is known, is is possible to predict the rate at which the enzyme is produced? Is there an equation ...
Vicenzo DeVito's user avatar
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Bi-phenyl degradation pathway in lignin

I am studying lignin - and really like the bi-phenyl degradation pathway of DDVA by SYK-6, as shown below But I can't find any literature on whether this pathway transfers from the dimer to the ...
erdos's user avatar
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Reason for sorbitol synthesis in human body

Sorbitol has been proved to be a major contributor to development of complications due to chronic diabetes. It forms in retina, lens, kidneys, peripheral nerves, ovaries and seminal vesicles by the ...
Vibhav Agarwal's user avatar
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Covalent modification of Pyruvate Kinase in RBCs

Human body has 4 isozymes of PK and I am particularly interested in the RBC isozyme. It is capable of being covalently modified through phosphorylation catalysed by Protein Kinase A which is in turn ...
Vibhav Agarwal's user avatar
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Efficiency of molecular motors vs. human-made motors

On the wikipedia page for "Molecular motor", it says "In terms of energetic efficiency, this type of motor can be superior to currently available man-made motors." without any ...
nullspace's user avatar
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Is there a DNase that works at low temperature, and is it also commerically available?

In preparation for FACS, I need to keep mammalian neurons on ice (in PBS-- / BSA), but as they still die while waiting ~30 minutes, they release their DNA into the solution. This leads to cell clumps. ...
bud.dugong's user avatar
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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 ...
Sadegh Rizi's user avatar
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Why does an Enzyme-Substrate Complex have slightly less energy than the substrate alone?

In some books the graph of the change in free energy during an enzyme-catalysed reaction is depicted as shown below, where S = substrate, E = enzyme, P = product, and T* represents the transition ...
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How Difficult is Artificial ATP Synthesis?

One way of making ATP requires: A membrane (would probably have to be a phospholipid bilayer) A difference in H+ chemical potential across the membrane ATP synthase anchored to the low-potential side ...
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Immunoaffinity chromatography: avoiding damage to the antibodies from proteases

What are the possible methods to prevent the digestion of antibodies (mainly Polyclonal) by proteases during affinity chromatography? I read some papers about doing modifications to the anitbodies: ...
Alpha's user avatar
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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 ...
Luckystrikerr's user avatar
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What lysis buffer recipe is good for just breaking the cell membrane?

I am interested in the decellularization of plant leaves(more specifically maple) and thus need a lysis buffer. I want the buffer to only break the cell wall and cell membrane and I want to observe ...
Aakarsh Tathachar's user avatar
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What enzyme could you use to delipidate lipidated serine?

I have a protein with a serine modified with an O-octanoyl group (ester linkage). What enzyme could I use to remove this group? Could I use a lipase, such as pancreatic lipase?
WaterMolecule's user avatar
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Why is random protein selection not used more often in biotech to create proteins with desired enzymatic activity?

mRNA/cDNA display allows random libraries of up to ~ 10^13 proteins to be subject to selection for binding to arbitrary binders. In the listed studies, proteins selected for ATP binding also had ATP ...
symmetrickittens's user avatar
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What keeps pyridoxamine phosphate inside the aminotransferase enzyme active site?

In the function of an aminotransferase enzyme after the first substrate (amino acid) has been deaminated there seem to be nothing binding the resulting pyridoxamine phosfate to the rest of the enzyme (...
AlexanderCar's user avatar
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1 answer
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Is there a way to refine a low resolution Cryo-EM structure using high resolution partial crystal structures?

I'm working on running simulations of human topoisomerase IIa. These are best done by starting with high resolution structures to ensure the system is as accurate as possible. However, no crystals ...
Paul's user avatar
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Is there a term to designate the property for an enzyme of catalyzing several reactions from the same substrate?

LacZ (beta-galacosidase) catalyzes the hydrolysis of lactose into either galactose and glucose or allolactose. Is there a term to designate such property for a single enzyme of catalysing several ...
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Why aren't complex-stabilizing proteins like transcription factors considered catalysts/enzymes?

I'm not asking the question on a superficial level. Obviously, (most) transcription factors are not acting directly on a substrate to produce a chemical change. I pose the above question as more of a ...
curious_catalyst's user avatar
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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 ...
Olivier Ma's user avatar
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Is CRISPR mediated RNA editing less specific and less efficient than DNA editing?

According to this diagram, the high efficiency and the high specificity of CRISPR lies in its reversible binding with the target DNA. The Cas protein unzips the target DNA and have the gRNA to base ...
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Are there irreversible metabolic reactions that can happen in opposite ways depending on the cellular conditions?

Irreversible reactions are thermodynamically irreversible, not microscopically irreversible. "Irreversible" here means the reaction happens "out-of-equilibrium". It is a ...
The Quark's user avatar
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What is the function of dihydrofolate reductase in humans?

According to StatPearls, synthetic folic acid — as an artificial dietary supplement — needs to be converted into the active form tetrahydrofolate (THF) by dihydrofolate reductase. In the cells, folic ...
toxicodz's user avatar
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Nature of firefly Luciferase reaction mechanism?

The bioluminescence of the firefly luceferin (FL) is a two step process, with the first step requiring the enzymatic/catalytic ability of the luciferase to convert the FL into luciferyl adenylate. ...
Evamentality's user avatar
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Why does pancreatin affect the pH of milk? [duplicate]

I just finished a lab for college and I was really intrigued by this. Since we're in a rush to finish the semester on time my professor didn't go into details much she just said something about fatty ...
wheeinsoup's user avatar
3 votes
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132 views

Does alternative splicing contribute to the diversity of enzymes?

I understand the role of alternative splicing in generating protein diversity, but for enzymes specifically, is alternative splicing responsible for the diversity of it? My professor told me something ...
Bread's user avatar
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Influence of pH on rennet coagulation of milk [closed]

I was looking for the reason why rennin works most efficiently at pH 6.7 (closer to a neutral environment than acidic).
Majd daas's user avatar
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Mechanism of the calcium-activated protein, Aequorin

In Aequorin, coelenterazine acts as the luciferin, producing light in the presence of calcium and oxygen. It is unclear to me what part of the protein structure actually catalyses this reaction after ...
Evamentality's user avatar
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is pepsin able to break down proteins into amino acids in human stomach? [closed]

I'm trying to find out if pepsin can break down proteins into amino acids after they are converted to peptides. Is pepsin able to separate amino acid monomers from the peptides? can you please show me ...
Parham Moieni's user avatar
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How does Clostridium perfringens cause target hemolysis?

I am studying microbiology as a part of my course and I was studying Clostridium perfringens. While studying its hemolytic characteristics, I came to know that it causes target hemolysis (i.e. zone of ...
ANA negative's user avatar
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What are the possible causes of Lactase persistence?

Lactase enzyme which is responsible for the digestion lactose (a disaccharide milk sugar) normally its production decreases when a young mammal is weaned but mostly Humens continue to produce this ...
Dr. Uzair Ali's user avatar
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Can we compare the effectiveness of an inhibitor by checking how much they change Km and Vmax during a reaction?

While comparing two inhibitors, can we check how they alter the Km and Vmax of the reaction and then decide which inhibitor is more potent. I tried explaining in this way: While I think the answer ...
Reverend Class Nought's user avatar
3 votes
1 answer
346 views

What other sites do non-competitive inhibitors bind to apart from allosteric sites?

I learned competitive inhibition and non-competitive inhibition. My teacher told me that we should say that non-competitive inhibitors bind to somewhere on the enzyme apart from active sites. I ...
Bruce M's user avatar
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Why can't humans digest dietary fiber when we can digest starch?

So, I can see that there's a couple of questions touching on this subject already, but none of them answer the aspect that I'm curious about: Dietary fiber is a polymer composed of multiple starch ...
nick012000's user avatar
1 vote
1 answer
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Why such strange enzyme kinetics?

I measured some enzyme kinetics in a practical course using a substrate-based FRET assay. Unfortunately some of my plots show weird effects. There was always a decrease in signal after 35 minutes. But ...
Mourinho_1's user avatar
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What is the dynamic range under initial conditions?

could someone help me to understand the following sentence better? It's from the book "A Practical Guide to Assay Development and High-Throughput Screening in Drug Discovery". And it's about ...
Mourinho_1's user avatar
2 votes
1 answer
111 views

Can enzymes be externally administered?

I was reading about Tay Sachs disease - it is essentially the deficiency of the enzyme hexosaminidase. Why can't the disease be treated by administering the enzyme (prepared artificially/extracted ...
raavee's user avatar
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Why does ATP act as an allosteric inhibitor of glycogen synthase?

Why is ATP an allosteric inhibitor of glycogen synthase? Wouldn't high levels of ATP in the cell mean that the cell has sufficient energy, and in this case wouldn't excess glucose be stored as ...
trinitrotoluene's user avatar
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1 answer
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What determines the nucleotides incorporated into RNA by polynucleotide phosphorylase?

Polynucleotide phosphorylase, in addition to its role as an exonuclease, is also involved in the post-transcriptional addition of nucleotides to RNA in a template-independent manner: “Polynucleotide ...
Samardeep singh's user avatar
1 vote
0 answers
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What is the effect of an acidic solution on hydrolytic enzymes?

I'm working on a school research project and my research question is "What is the effect of increasing concentrations of Acid X on hydrolytic enzymes, measured through the loss of mass of leaf ...
Sankalp Kapur's user avatar
1 vote
1 answer
234 views

Turnover number of the enzyme catalase

My textbook says that catalase is the fasting acting known mammalian enzyme and it can act on 40 million molecules of hydrogen peroxide per second. Does that mean that is acting on that number of ...
Kantura's user avatar
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Is the kinase domain of a protein kinase the same as the catalytic domain?

I am learning about protein kinases and I have read that the protein kinase domain is a structurally conserved protein domain containing the catalytic function of protein kinases. I am wondering ...
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Can a constitutively active kinase be highly regulated?

I am studying the protein kinase GSK3 and I am learning about the regulation of its activity. Many journal papers that I have read have stated that GSK3 is unique because it is a constitutively active ...
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Do phagocytes need antibodies to be able to engulf pathogens (to function)?

I recently saw a question about monoclonal antibodies, that are specific to a certain virus, being split (into their constant and variable regions via an enzyme), and the question asked whether some ...
123321123321's user avatar
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Enzyme inhibitor leads to higher turnover rate?

I'm currently working on a project where I have to deal with enzyme inhibition. The purified enzyme shows a good substrate turnover. When I try to inhibit it with different inhibitors described in ...
Mourinho_1's user avatar
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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 ...
starry's user avatar
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1 answer
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How do enzymes not change the overall energy change of the reaction they're catalysing if they lower the activation energy?

Based on the Induced-Fit model of enzyme action, enzymes catalyse a reaction by lowering the activation energy of a single forward reaction over and over. But I read that enzymes don't change the ...
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