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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Regarding the role of enzymes

Textbooks commonly state that the role of enzymes is to speed up a chemical rxn by lowering its activation energy. However, I'm unsure what enzymes like helicase, DNA/RNA polymerase, and restriction ...
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Can plants break down cellulose for energy?

I know humans and other animals start using their own proteins as food when starving. This made me wonder if a plant that is deprived of sunlight, after using up its sugar reserves and other carbs, ...
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Histone Deacetylase Inhibition

So I am trying to brush up on my knowledge of HATs and HDACs. I am reading the just the 1st paragraph of the background of this study I remember learning that HATs turn things on on, and HDACs turn ...
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Are there any small peptides with protease activity?

I'm looking for a very small protease to base an engineered protein on. I did a search for "peptides with protease activity" but all the results seem to be as peptides to be used as protease ...
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Why would Aspergillus Oryzae produce lactase when no lactose is present?

Studies [1] have shown that lactase is produced by A. oryzae when grown on wheat bran and spent beer grains. Why would A. oryzae produce lactase when these substrates have no lactose? In [1], it's ...
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Is there any current knowledge of how DNA polymerase is “motivated” to perform error corrections during transcription?

I was trying to understand the process of how polymerase performs error corrections on DNA. Every paper on this topic mentions what happens during the process, but there's no mention of how it happens....
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What is the definition of a polybasic cleavage site?

I keep coming across the term "polybasic cleavage site" which is implicated in increasing the virulence of many viruses, but I'm struggling to find a definition. Is it just a sequence of amino acids ...
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How is the protease inhibited by lopinavir different in SARS-CoV-2 compared to SARS-CoV?

The protease inhibitor lopinavir, originally developed as a cure against AIDS and HIV, has been shown efficient against SARS Coronavirus SARS-CoV. Dayer M R, Taleb-Gassabi S, Dayer M S. Lopinavir; ...
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How is honey not toxic to our epithelial cells?

Being a supersaturated solution of sugar, honey pulls the water out of cells it comes in contact with via osmosis - killing the cells. It also contains the inactive enzyme glucose oxidase, which when ...
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What is allosteric regulation?

I've found multiple definitions for allosteric regulation and struggling to understand which one is correct. My text book says: 'Another way of regulating enzyme activity is through allosteric ...
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AChE aging time of organophosphates containing hydroxyl groups

Organophosphorus compounds are known to inhibit the enzyme acetylcholinesterase (AChE). This occurs when the organophosphate phosphorylates the serine-203 residue of the enzyme. If the enzyme is not ...
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Regulation of the TCA cycle and glycolysis by adenine nucleotides

Why is the tricarboxylic acid cycle regulated by the ADP/ATP ratio as stated in the following quote : Isocitrate dehydrogenase is allosterically stimulated by ADP, which enhances the enzyme's ...
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Glucose 6-phosphate dehydrogenase: reaction mechanism

I have searched the internet for the reaction mechanism of G6PD but couldn't find it, so I am asking whether anyone here knows its mechanism and whether they could recommend some sources that give ...
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Photolysis in the Light Reactions of Photosynthesis [duplicate]

I'm a bit confused concerning photolysis. During the light reactions, photons are used to excite the chlorophyll molecules so they are passed to the primary electron acceptor. The electrons initially ...
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Cellulase Sample Digestion Protocol?

Is there an effective way to use cellulase(s) and/or lignase(s) to remove unwanted plant debris from a sample? I'm working with a series of fresh water grab samples for environmental assessment. The ...
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How is plasmin formed from plasminogen?

In Ganong's Review of medical physiology it is mentioned that plasminogen is converted to active plasmin when tissue type plaminogen activator hydrolyses the bond between Arg560 and Valine 561. Can ...
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What's the difference between mannanase and mannosidase?

Specifically, in Aspergillus spp mannandegrading enzymes. I saw this table at the BRENDA's page for 3.2.1.25 and 3.2.1.78 enzymes and the synonims are reciprocal to me. So, why a mannanase is also (...
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How can we digest lactose even though it has Beta glycosidic linkages?

I have Read that we cannot digest cellulose because we do not have enzymes to digest Beta glycosidic linkages in Cellulose Then how is it that we have an enzyme called Lactase to digest the Beta ...
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Can enzymes be modeled using classical mechanics?

When enzymes interact with substrates (i.e. a small ADP molecule and the much larger ATP synthase), does quantum mechanics play a significant role? Or can the interactions be relatively accurately be ...
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What happens if an enzyme stops working in the body?

For example, if the enzymes in the digestive system stop working will the digestion still occur as enzymes are only catalysts for the reactions. Thank You
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Looking for a good and complete Enzimology exercises book

I mean, I want to practice with challenging exercises and I want to know the theory behind them. So, I started reading: Organic Chemistry: Yurkanis, P. Enzyme kinetics: Bisswanger, H. Biotechnology ...
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Cheap enzyme assay for a high school lab

At the moment, I'm designing an experiment for a high school lab with no financial resources. I need to assess the impact of a variety of factors on a specific enzyme's reaction with its respective ...
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Where is catalase produced?

I am doing a research project on the peroxisomes, and in it I referenced the enzyme catalase, which breaks down hydrogen peroxide into water and oxygen. However, the assignment asks me to specify the ...
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How does the helicase enzyme break the hydrogen bonds between the strands of DNA?

I know helicase breaks the hydrogen bonds between the strands of a DNA, but how is this done? Does it put an ion between the strands of the nucleic acid so that the bond breaks apart itself or is ...
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Speed of reaction vs equilibrium

Does increasing the speed of a reaction (say by introducing a catalyst) shift the equilibrium of the reaction? I assume it does not, as Gibbs free energy is not changed, but I am not sure.
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Do there exist enzymes that can take up multiple cofactors to do different reactions?

I was thinking about enzyme catalysis, and it seems like enzymes can only catalyse one kind of forward/reverse reaction (please correct me if I am wrong). Does there exist an enzyme that can catalyse ...
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When do enzymes catalyze reaction of both direction and when do they not? [duplicate]

I've read that enzymes can catalyse both forward and backward reaction so they don't change eqm position etc. However protein kinase catalyses phosphorylation, while phosphatase catalyses ...
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What are the marker enzymes for Nucleus, Ribosomes and cell membrane?

Are there any marker enzymes present for ribosomes, nucleus and cell membrane. For mitochondria there are many, for lysosome it's cathepsin. I read about the marker enzymes of most of the other ...
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May two reactions, that share the same reactant, fire at the same moment?

I'm studying metabolic networks from a bioinformatics point of view, but I guess my question is pretty biological so I thought that maybe here I could get the best answers. So, as the title says I ...
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Will amylase inhibitors affect the colorigenic reaction between starch and iodine?

I'm doing an experiment for my IB bio EE involving colorimetry. I'm not experienced at all with colorimetry, so I'm having some trouble planning it. The experiment is on enzyme kinetics, and I'm ...
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Why is the GULO pseudo gene expressed in humans?

The GULO pseudo gene is being expressed in humans according to Genecards. Why is this still taking place after tens of millions of years since then gene lost the capacity to encode for a functional ...
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What enzyme or bacteria could dissolve plastic?

What enzyme or bacteria could dissolve plastic aside from acetone? Preferably, low-cost and environmentally friendly. Any suggestions would be helpful. I'm targeting for thin plastic (low-density ...
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Cooperative Enzyme Question

I'm currently studying for the MCATs. After doing some biochemistry practice questions, I came upon a question that I believe may be incorrectly posed. I was wondering if I'm correct in saying this or ...
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How do NSAID's work and what are the differnces between COX-1 and COX-2? [closed]

NSAID's work by slowing down the COX enzym, but how do does enzymes cause pain? because I've read that they're also needed for the body and do "good" things.
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How could pharmaceutical metabolizing bacteria be used to synthesize them?

Lets say I have a pharmaceutical "P". It can be broken down by enzymes of one strain of bacteria into two molecules one of which can be further metabolized enzymatically by a different strain of ...
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which enzyme phosphorylates sodium potassium pump?

I know that Na+/k+ pump possess atp-ase function; so the pump will hydrolyze ATP into ADP + Pi. And I see in a figure that the pump is phosphorylated but couldn't really find which protein catalyzes ...
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Does digestion require hydrochloric acid?

Would our digestion function any differently if we secreted something else, like sulfuric or nitric acid, instead? I'd assume an acidic environment may be required, but not sure if chloride is also ...
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How do fatty acid and polyketide synthases handle the varying size of their substrates?

Polyketide synthesis involves six modules, each containing certain common constituent enzyme activities (KS, AT, KR) that are involved in extending the chain (see e.g. Dutta et al.(2014) ). The ...
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How can P450 distinguish between foreign and native compounds?

It is my understanding that P450 enzymes are capable of selectively degrading compounds that enter the cell from the outside (e.g. synthetic drugs) without damaging compounds that are metabolic ...
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How long does an enzyme work?

I googled this, and I found only that shelf lives are around 2-3 years, but the enzymes use to work even after 5 years if you store them properly. I'd like to know how long I can use an enzyme in ...
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How do DNA, enzymes, hormones etc. reach their proper cellular locations?

I was trying to understand DNA transcription from this chapter, and there seems to be no explanation on how exactly the proteins, enzymes and other molecules manage to find each other inside the cell. ...
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Enzyme inhibitors against common cold viruses

Would some inhibitors of viral enzymes work against common cold viruses? Are there any studies? What could a treatment look like? A lot of common cold viruses are rhino viruses which are picorna ...
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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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Do we know how dangerous six-eyed sand spiders are?

The Sicariidae family contains the well-known and dangerous Loxosceles spp. (fiddle-backs, violin spiders). The family's other two genera, Sicarius and Hexophthalma (six-eyed sand spiders) have ...
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Are all enzymes proteins?

So throughout my education and research career I have been taught that all enzymes are proteins. This makes sense when you consider enzyme denaturing and folding/shape etc. However, I was recently ...
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Are there any enzymes without aromatic amino acids?

I'd like to try a new spectroscopic technique to study enzymatic reactions (which reaction doesn't especially matter, something simple and with fast kinetics like catalase would do fine - I'm just ...
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How to calculate the turnover number?

I understand that Kcat (turnover number) = Vmax/total enzyme concentration. However the formula I have been given is Kcat = specific activity/molecular mass of enzyme. What is the relationship ...
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How can we quantify the effect of pancreatin (biological enzyme) on the clarification of milk powder

Alright so I'm trying to quantify the rate at which casein (protein constituent of milk powder) is converted into a product (I am unaware of) by pancreatin (a biological enzyme that speeds up the ...
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What are the effects of enzyme exposure to high temperatures? [duplicate]

Question: After enzymes are exposed to high temperatures and undergo denaturation, then returned to their optimal temperature and renatured, can the enzyme's active site return to it's original shape ...
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Why does M1 RNA together with C5 protein in 100mM Mg(II) fail to cleave tRNA?

Sidney Altman discovered that RNA moeity of RNAse P (M1 RNA) alone is able to perform enzymatic cleavage of ptRNA, which won him the Nobel Prize of Chemistry in 1989. However, when I read the Nobel ...

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