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
166 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 ...
2
votes
0answers
20 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
43 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
198 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
108 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
37 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
47 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
41 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
25 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
18 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
135 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
39 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
22 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
24 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
66 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
194 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
47 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
85 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
126 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
97 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
74 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
29 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
624 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
108 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
31 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
46 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
977 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
262 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 ...
22
votes
3answers
371 views

How crowded is the bacterial cell?

I was wondering what is the protein concentration in an E. coli cell. When studying enzyme kinetics and activity in vitro, I would argue that the substrate and enzyme concentrations resemble those in ...
7
votes
3answers
111 views

Can any enzyme be produced?

After reading about how recombinant insulin is produced, the following question occured to me. Does the current level of technology allow any enzyme to be produced in a similar way? As I see, ...
1
vote
1answer
148 views

How will changing the concentration of a Tris buffer affect amylase enzyme activity?

For instance if you increase the amount of Tris but pH still does not change then will the enzyme activity still proceed normally? If it does change the pH will it change enzyme structure and why?
2
votes
1answer
277 views

Do the enzymes and compounds in saliva help with stain removal?

Does spitting on stains help with removal? Saliva is high in amylase that should help with the breakdown of protein rich stains like blood and semen. It also contains antimicrobial enzymes and ...
1
vote
1answer
31 views

How is Glycophorin A and straphylococcal related to Escherichia coli and what does readily purified mean in this context?

I am reviewing the paper "Glycophorin A Dimerization Is Driven by Specific Interactions between Transmembrane Alpha-Helices." There is a statement in the abstract which I don't understand: "The ...
0
votes
0answers
44 views

Nagalase testing any good?

Is Nagalase testing good to detect if something is wrong in the body (ex: cancer)? The next problem I assume would be to know what/where the problem is. To put it an other way: If I understand ...
2
votes
1answer
39 views

Is NADPH unstable in UV light?

I am working on an enzyme activity assay using NADPH as a cofactor. The MSDS for NADPH Tetrasodium Salt, tells to store it in a place away from heat and light. Does this include UV light or just ...
3
votes
1answer
166 views

Enzyme Assay - pectinase

During assaying an enzyme at high temperature, the substrate (Pectin) is degraded by the high temperature rather than by enzyme, so, how can I minimize degradation of the substrate by the temperature? ...