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.

learn more… | top users | synonyms

1
vote
1answer
22 views

Why does uncompetitive inhibition decrease the Michaelis constant?

I can't seem to find a good resource online that clearly outlines the difference between an uncompetitive, noncompetitive, and mixed inhibitor (I understand competitive inhibitor though). More ...
1
vote
1answer
11 views

How are constitutive enzymes regulated?

I found that inducible enzymes can be regulated by many ways, but I cannot find how constitutive enzymes are regulated...
1
vote
1answer
18 views

Why is the formation of an enzyme-substrate complex endergonic (induced fit model)?

In the section about the induced fit model for enzyme substrate binding, my MCAT textbook claims that "The substrate has induced a change in the shape of the enzyme. This interaction requires energy, ...
3
votes
2answers
41 views

Do disaccharidases require a cofactor or coenzyme to function?

I'm doing research on lactose intolerance and am curious if disaccharidases (enzymes that break down disaccharides) require a cofactor or coenzyme to function? Reviews or references would be greatly ...
-1
votes
1answer
41 views

How does imatinib recognize the constitutively active Abl-BCR even though it binds to the inactive conformation?

In chronic myelogenous leukemia (CML) ABL-BCR is constitutively active (always on) and it can be inhibited by imatinib and dasatinib. A study says that imatinib binds to the inactivated state of the (...
1
vote
1answer
215 views

sodium chloride and amylase activity

So, I did an experiment on the effect of sodium chloride on amylase. and I found out the higher the concentration, the slower the activity. Therefore, is it valid to make the assumption that when we ...
1
vote
0answers
16 views

Are there any individual animals that can thrive in a wide range of core temperatures? [closed]

Surely, some cold blooded animals are in a position where they can't escape the changing temperatures the environment throws at them, so natural selection would have enabled them to thrive in a wide ...
0
votes
1answer
23 views

Enzymes and Reversibility of Reactions

Richard Feynman mentions in the third chapter of The Feynman Lectures: So the real system is in the GDP-GTP transformation; in the dark the GTP which has been stored up during the day is used to ...
1
vote
1answer
30 views

What can saliva tell about ones health? [closed]

I was wondering if I d want to analyze something related to my current health based on my saliva. What could it be? I mean e.g. by putting a thermometer in your mouth you can know your body ...
2
votes
0answers
21 views

Does alpha-amylase from different species have different *optimal* conditions?

Do the optimal conditions for the enzyme isoforms differ between species? Specifically, do the optimal pH and temperature for alpha-amylase differ for that enzyme produced by B. lichiniformis and A. ...
5
votes
1answer
45 views

EC number classification of synthase?

It is quoted in wikipedia that: Following the EC number classification, they belong to the group of ligases , with lyases catalysing the reverse reaction. And we all know that enzymes are ...
7
votes
1answer
276 views

Why is aconitase classified as a lyase?

Aconitase in the TCA (tricarboxylic acid) cycle isomerizes citric acid to isocitric acid via cis-aconitic acid intermediate. Since overall it functions as an isomerase, why it does not belong to ...
1
vote
0answers
69 views

How do you measure enzymes from the blood? [closed]

How are enzymes(DAO - diamine-oxidase for example) in blood measured? What kind of machines are used? What are the major steps used when I get tested in a lab? Is this process adaptable to an ...
0
votes
0answers
30 views

If I were to flush enzymes down with a cellulose rich food, what would happen?

Lets say I were to consume an adequate concentration of cellulase and cellubiose with a cellulose rich food. Would nothing happen, would I successfully extract calories from the cellulose, or would it ...
6
votes
3answers
121 views

Function of the alpha subunit in mitochondrial ATP-synthase?

Within the catalytic core of mitochondrial ATP-synthase there are two different types of subunits; $\alpha$ and $\beta$. From what I have read, the catalytic sites occur only in the $\beta$ subunit so ...
0
votes
1answer
39 views

Relative concentration of enzyme vs reaction product

I was reading a paper in which a recombinant protein (His-6 tagged) is expressed in E Coli (BL21 DE3). The yield of the enzyme isolated from the culture is reported as 10-30 mg per L of bacterial ...
3
votes
2answers
49 views

Can ELISA be used to detect a plant enzyme? Creating assay for a new enzyme

If the goal is to generate a rapid assay for an enzyme of plant source what are the typical options? i.e. Could one do something like: Generate an antibody to the enzyme and then use it to create an ...
1
vote
1answer
29 views

Enzyme Inhibitors: Using in vivo in yeast

I find listed on the Sigma-Aldrich site a large list of enzymes & corresponding inhibitors. e.g. For the enzyme squalene synthase the inhibitor listed is "Zaragozic acid A trisodium salt" Would ...
0
votes
1answer
53 views

Reason Non linear Lineweaver–Burk plot [closed]

V vs S plot looks like hyperbolic but 1/V vs 1/S plot is not linear at all. Looks like some kind of exponential growth. What can be the reason?
1
vote
1answer
28 views

Does the Michaelis-Menten equation take in account the non-enzyme formation of products?

I only recently learned about the Michaelis-Menten equation recently, since I am not studying biology or anything related. Let's write the equation as $$\frac{d[P]}{dt} = V_{max} \cdot \frac{[S]}{K + [...
1
vote
1answer
16 views

RNAse activity review

I was searching for any review unravelling the structure-function motifs responsible for RNAse activity. Or at least a well-composed review of RNAse superfamilies that are described nowadays (with ...
4
votes
1answer
26 views

Enzymes and Digestion

If biological enzymes (protease,amylase,lipase etc.) just speed up the reaction (in the digestion process), then what actually digests the food?? (I'm a secondary student)
1
vote
0answers
20 views

Enzyme immobilization: Factors that help or hurt success

Are there any factors to consider that can help / hurt the chance to get a successful immobilized enzyme catalyst? i.e. The relative attractiveness of a live host synthesis vs an immobilized enzyme. ...
2
votes
0answers
51 views

Real Wine and Real Bread Superfoods? [closed]

On NPR news on the Fm Radio a doctor said wine and bread is the best 2 things you can eat together? A practice observed to this day by Christianity although the bread and wine are badly stripped of ...
4
votes
0answers
29 views

Derivation of Michaelis' Equation from Michaelis' Constants [duplicate]

The enzyme reaction condition, $E + S \leftrightarrow ES \rightarrow E + P$ uses $\kappa_{1}$ (forward reaction), $\kappa_{-1}$ and $\kappa_{2}$ as the rate constants. E: Enzyme S: Substrate P: ...
3
votes
1answer
64 views

Which enzymes degrade dynorphins and what drugs inhibit these enzymes?

Which enzymes degrade dynorphins and what drugs are there available to inhibit said enzymes?
1
vote
1answer
199 views

Difference between negative allosteric regulation and non-competitive inhibition

Both connect to some site other than the active site which controls the shape of the active site and causes the enzyme to be less active. So what is the difference?
0
votes
1answer
43 views

Aspirin - does it inhibit enzyme of thromboxane?

This is a diagram a friend showed me about the drug aspirin, where we were arguing which enzyme it prevents. Aspirin is known to inhibit the production of prostaglandins. However, it also serves ...
0
votes
2answers
23 views

Can an enzyme be activated without allosteric inhibition or activation?

Are there ways by which an enzyme may be activated or inhibited by non substrate molecules other than allosteric activation or inhibition?
0
votes
0answers
8 views

Is there a deblocking aminopeptidase without normal aminopeptidase activity?

The deblocking aminopeptidase is a unique exo-type aminopeptidase that liberates blocking groups (formyl, acetyl, and myristyl) from proteins and peptides. However, according to this paper, it has two ...
1
vote
0answers
26 views

Is it possible to separate the binding and catalysis of an enzyme in two steps?

Is it possible to do the following: Enzyme E binds to its substrate S without catalysis; Add a controllable stimulus, such as light, adding or removing chemicals; The enzymatic reaction is triggered ...
3
votes
1answer
71 views

Do we actually know the molecular dynamics of any enzyme?

That is right, is there a limitation, say Heisenberg's uncertainty principle or something that limits our understanding of machinery of enzymes at atomic level? Can we know how do they actually work? ...
3
votes
3answers
4k views

Why does pH have an effect on enzymes?

I am currently studying biology and have a question about how pH affects enzymes. When the pH gets closer to the enzyme's pH optimum, the enzyme activity also increases. I would like to know why? ...
0
votes
2answers
202 views

Why is succinate dehydrogenase attached to the inner mitochondrial membrane?

Succinate dehydrogenase is attached to the inner mitochondrial membrane. All the other enzymes of the Krebs cycle are located within the matrix of mitochondria, though. In biological systems, there ...
2
votes
1answer
1k views

Making the sense of enzyme Km comparisons

I have encountered comparisons of the Michaelis-menton constant (Km) a few times. Generally speaking if Km of an enzyme is higher, then it's affinity to its substrate is lower. How does this make ...
4
votes
3answers
49 views

Is there a database providing information about optimum temperature and inactive temperature of enzymes?

I want to know optimum and inactive temperature of some enzyme, but I can't find these information in NCBI, wiki or UniProt. So I want to know if there are some database which provide these ...
1
vote
1answer
86 views

What is a detailed chemical explanation for describing how an enzyme may lower the activation energy of a reaction?

If you can provide some sound reasoning that touches on tertiary structures of proteins and does not use a lot of advanced chemistry jargon that might be really helpful, especially for an intro ...
1
vote
0answers
143 views

How to calculate the LOB, LOD and LOQ of an enzyme assay

I understand how to calculate limit of blank (LOB), limit of detection (LOD), and limit of quantitation (LOQ) in the traditional way i.e., average and SD of raw analytical signal of blanks and low ...
1
vote
1answer
108 views

Why is binding energy the difference between ∆G catalyzed and ∆G uncatalyzed?

I think the title explains it pretty well -- I'm confused on what 1) exactly binding energy is 2) and why it's the difference. Like in this diagram: my teacher sort of said it was the energy the ...
0
votes
0answers
20 views

Will a metalloenzyme bind to its substrate in the absence of its metal ion cofactor?

A metalloenzyme is an enzyme using a specific metal ion as its cofactor. Their activity is dependent on this metal ion. For example, the T4 DNA ligase requires Mg2+ to ligate DNA strands; The ...
2
votes
0answers
75 views

Proteases in the blood

I’m reading on hormones and the book talks about how peptide or amine hormones are easily broken down by proteases present in the blood plasma. This has led me to question the interactions between ...
2
votes
0answers
31 views

What's the purpose of Cdk activity having more than one method of becoming inactive?

Cdk becomes partially active once its bound to cyclin and then gets phosphorylated and fully active once a Cdk-activating kinase (CAK) phosphorylates the partially active Cdk. This fully activated Cdk ...
2
votes
2answers
16 views

Affinity Column of membrane bound receptors

I understand affinity columns can be used to study the ligand/enzyme affinity. But is an affinity column able to be used for membrane bound receptors? I
2
votes
1answer
634 views

How to calculate or know by experiment the entropy of enzymes or protein?

How do you calculate or experimentally determine the entropy of enzymes or protein? In particular, I am interested in Boltzmann and conformational entropy, and Gibbs free energy. Any references are ...
2
votes
1answer
109 views

Dwell time equations for ATP-sythase?

I have read that every 120 degree rotation of the F1 complex of ATP-synthase can be split into a 30 degree rotation and a 90 degree rotation. In between these two are dwell times, the one before the ...
0
votes
0answers
39 views

What cures pineapple burns?

If you already ate too much bromelain in pineapple, how do you cure your tongue burn?
1
vote
0answers
32 views

Invertase calculation?

If I wanted to make $500\mathrm{\mu g}/\mathrm{ml}$ of invertase, from Sigma's Invertase from Baker's yeast, which states is grade VII, and greater than or equal to $300 \mathrm{units}/\mathrm{ml}$, ...
0
votes
0answers
48 views

Enzymes and cofactors

About how much % of the human enzymes need cofactors? Like 20%, 30%, or 50% of a cell's enzymes? And how many enzymes work "alone"? This is a general question to figure things out. Do most enzymes ...
11
votes
1answer
991 views

Grapefruits and CYP3A4

Grapefruit juice contains furanocoumarins, which irreversibly inhibit CYP3A4. For this reason, when one is taking certain medications it is necessary to not eat grapefruits because the inhibition of ...
5
votes
1answer
292 views

Why is it often the case that an enzyme is favorable only towards one direction of a reaction and not both directions?

In class when we're studying enzymes like amylase or protease it only works well when you're using it to break down compounds like polysaccharides. I'm just curious but why is it not possible for ...