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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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 ...
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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 ...
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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. ...
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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 ...
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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 ...
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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).
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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 ...
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What are the SNPs responsible for PCSK9 expression?

My understanding is that PCSK9 is an enzyme that affects how cholesterol is cleared from the liver, and thus how how high or low the LDL cholesterol number is in a person. I'm curious to know what are ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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1 answer
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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 ...
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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 ...
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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 ...
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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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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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Why are many skin depigmenting agents toxic to the body?

Coming from a developing country, I know many people who regularly use these creams to lighten their skin and some of them have developed liver and kidney problems as a result. I know that many ...
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Do carboxylesterases, arylesterases and acylesterases count to the enzyme class of lipases? [duplicate]

I am currently examining the acyl transfer catalysis activity of several enzymes that I was told are all lipases. Through reading a couple of papers including these enzymes I found out that all of ...
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Basis of enzyme nomenclature — pyruvate dehydrogenase

In the formation of AcetylCoA from pyruvate, why is the enzyme called “pyruvate dehydrogenase (complex)” when it involves the decarboxylation of pyruvate or the replacement of a carbonyl group by ...
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Which enzymes use ATP?

It is well known that there are many enzymes which use ATP in their function, and any enzyme that work against an energy gradient need to have that energy supplied from somewhere, but just as well ...
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Are there ribozymes that cut double strands

the header already says: Are there any ribozymes known that cut double strands? A kind of ribozyme equivalent to the Ribonuclease III. With cut, I mean that the backbone of both strands, forming the ...
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What is the "GTP activator protein" that activates GTP-cyclohydrolase-1?

From GTP-cyclohydrolase deficiency responsive to sapropterin and 5-HTP supplementation: relief of treatment-refractory depression and suicidal behaviour (BMJ Case Reports, 2011) The metabolic profile ...
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ATP Synthase EC number

Why ATP synthase EC number is 7(Translocase)? My textbook says it's a hydrolase but when i checked its EC number it was changed to 7. And also ATPase(adensointriphosphatase) page that was previously ...
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Will Saliva make food go bad

My mom was telling me that if I put the unfinished bowl of milk and cereal back to the fridge, the saliva that has been stuck to the spoon gets passed to the milk. The saliva in milk will make milk go ...
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Alkaline Phosphatase and Ligase Protocol for Cloning

In the image the circular molecule is a restricted vector and the linear red molecule is a DNA insert. I found this protocol in my lessons notes, but I don't understand how it is possible that ligase ...
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4 votes
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Structure and reactions of the cofactors of oxidoreductases such as ferredoxin

I have seen the word flavoprotein being used in place of ferredoxin in few places and vice-versa. I have not found any source that mentions them both together and explains the relation between them. ...
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Calvin cycle- combining three "turns"

In the common Calvin cycle diagram, it is commonly stated that "three cycles are combined to show the production of 1 molecule of G3P". How does the G3P molecule escape from this cycle in ...
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Why do some enzymes have giant structures around the active site?

As a part of my inorganic chem. course (it's a required course at my college), we have a module called Introduction to Bioinorganic Chemistry. There, the prof. showed examples of enzymes like ...
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Why can't C1r cleave C4 proteins?

I am researching the complement system, and have ran into something I'm not really sure about. In the past, the C1r2s2 complex was thought to be an 8-like structure tucked inside C1q's collagenous ...
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Does Topiramate work by supplanting Pyridoxal phosphate in enzymes?

I have seen it said that the precise mechanism of action of migraine medicine Topiramate is not known. But I certainly see a resemblance between that molecule and PLP (Pyridoxal phosphate, the ...
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Lower optimum temperature of plant Catalase

Most resources give an optimum temperature of 35° C for Catalase. after performing the AP Catalase enzyme lab in school, using blended potatoes, our results gave a greater reaction rate at a room ...
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1 answer
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Why is this oxoglutarate dehydrogenase and not oxoglutarate decarboxylase?

I was looking at the oxoglutarate dehydrogenase complex and saw the reaction mechanism for its E1-TPP mechanism, which results in the formation of a stabilized carbanion intermediate. The mechanism ...
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1 answer
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Meaning of some unit of measurement of kinase activity

I need help knowing what $cpm \times 10^3$ means in Figure 4(C) of this paper (https://www.sciencedirect.com/science/article/pii/S0022202X15323149#f0010). It appears to be a unit of kinase activity.
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AMPK, PAN-AMPK, western blot

What does it mean by adding PAN before the AMPK. I am trying to do a western blot assay on AMPK and I am confused by PAN-AMPK, AMPK. does it mean pancreases? Is pan-ampk the total ampk?
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What changes do ants make to the soil they use for building ant hills

I live in South India ,and among the many species of ants in and around our house, some of them except the weaver ants build the typical small ant hills in the garden. I have examined the coarse sand ...
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What is "KK1 enzyme"?

In the book "The Kaizen Way" by Robert Maurer, I've read the following: When we’re sitting, our muscles go into a form of hibernation, causing our bodies to shut down the enzyme (called KK1)...
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What is the function of human Trypsin Inhibitor if trypsin is secreted in the inactive form of Trypsinogen? [closed]

I was reading about pancreatic digestive enzymes in a Textbook of Medical Physiology and I came across Trypsin Inhibitor. The text stated that: It is important that the proteolytic enzymes of the ...
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Can Mung Bean Nuclease only digest a ssDNA 5' overhang?

Can Mung Bean Nuclease only digest a ssDNA 5' overhang, if the double-stranded region of DNA (20bp) is A-T rich at the ends? Does this enzyme degrade 5' overhang (5bp or 30 bp) with 100% efficiency?
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