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.

Filter by
Sorted by
Tagged with
3 votes
1 answer
170 views

What is the difference between Leloir and Non-Leloir glucosyl transferases?

The following questions were on the slides for my biotech course and I haven't been able to find any information on what the answer is. What is the difference between Leloir and Non-Leloir glucosyl ...
Berghor's user avatar
  • 87
0 votes
1 answer
189 views

Health benefits & enzymes different between Thermophilic and Mesophilic Probiotic cultures?

Is there a difference between the Enzymes produced by Thermophilic vs Mesophilic Probiotic cultures ? are there any other differences in health benefits between the two types of cultures ?
Neel's user avatar
  • 125
1 vote
2 answers
277 views

How can ionized amino acid form be important for the catalytic activity?

I can imagine that protonated amino acid form, particularly at the active site, is important for the catalytic activity so hydrogen bonds can be created between the substrate and the enzyme. However, ...
Mohammed Noureldin's user avatar
1 vote
0 answers
135 views

Is osteoid an uncalcified substance?

I recently learned about Osteoid (the substance secreted by osteoblasts during intramembranous ossification), and I read that it was an "unmineralized organic component of bone." Now, does this mean ...
ScienceGirl1234's user avatar
1 vote
1 answer
801 views

How can some residues in the active site of enzymes be protonated with a pKa < 7?

It is reported in many papers, that some residues in the active site of enzymes need to be protonated to get functional enzyme, where these residues have a low pKa (for let us say 5). How can that ...
Mohammed Noureldin's user avatar
0 votes
1 answer
1k views

Does pepsin digest plant protein?

This may sound trivial, but... Protein is sourced from plants and animals. Pepsin and HCl digest meat (animal protein). Does pepsin also digest plant-based proteins? I took a look at few articles ...
bonCodigo's user avatar
  • 531
4 votes
2 answers
6k views

What are the differences between isozymes, allozymes and isoforms? [closed]

As far as I have understood Isozymes are derived from different genes but perform similar functions Allozymes are derived from the same gene but different loci, functionally conserved Isoforms are a ...
Rajinder's user avatar
2 votes
0 answers
384 views

Specific activity vs turnover number of enzymes in BRENDA

From my understanding, the specific activity (A, units: umol/min/mg protein) can be derived from the turnover number (k, units: 1/seg) and the molar mass of an enzyme (MW, units: g/mol): A = k / MW / ...
a06e's user avatar
  • 1,347
5 votes
1 answer
130 views

What might a supposed “tree enzyme” be — injected into a Morton Bay Fig tree?

I was recently visiting Fremantle in Western Australia and noticed a large Morton Bay Fig tree in Kings square in the centre. Apparently the health of this tree had been declining, but they hope that ...
David's user avatar
  • 23.8k
1 vote
0 answers
45 views

What are the chemical characteristics of cofactors that functionally differentiate them from the side chains of amino acids?

Cofactors are essential for the function of many enzymes, such as NAD+ in the glycolytic pathway - I was wondering how the chemical properties of these cofactors allow them to fulfil their function ...
ooakley's user avatar
  • 171
2 votes
1 answer
365 views

Is the Insulin Receptor Considered an Enzyme?

Can we consider insulin receptor an enzyme? In other words, does the insulin receptor have enzymatic characteristics?
Reem M.Al Haj's user avatar
2 votes
1 answer
42 views

Screening Enzymes?

I wish to obtain a list of all known enzymes and then get rid of the ones that use cofactors, the ones that use ATP, and a few others. What is the easiest way to do this?
Dale's user avatar
  • 1,647
1 vote
2 answers
448 views

What are the structural factors affect enzyme's Km?

Is there any rules (should not be exact), to estimate the kinetic changes in an enzyme if I did any mutation on it? If I cannot estimate the new kinetic values, is it possible at least to clarify or ...
Mohammed Noureldin's user avatar
1 vote
1 answer
290 views

Could removing non-functional parts of coenzymes improve enzyme function?

As pointed out here, many important co-enzymes (essential enzyme cofactors) such such acetyl-CoA and vitamin B12 contain nucleotide portions that do not function in the enzyme catalysis. They have ...
Count Iblis's user avatar
3 votes
1 answer
2k views

If humans had cellulase would they be able to digest grass?

Cellulase is an enzyme capable of breaking cellulose. If humans were able to produce cellulase in our stomach would we be able to digest grass? If not, what more things would we need in order to ...
Ender Look's user avatar
1 vote
0 answers
817 views

Which enzyme curdles milk in human infants? [duplicate]

Following, this question - Do humans produce rennin? Rennin does not exist. And What inactivates pepsin in infants? Rennin exist. What do I know is- Rennin is found in calves and acts on milk to ...
Anubhav Goel's user avatar
3 votes
1 answer
55 views

What does metal-dependent mean?

I was reading about Cas1 and Cas2 and came across this excerpt: ...Cas2 was identified as a metal-dependent endoribonuclease that cleaves ssRNA or dsDNA... What does metal-dependent mean in this ...
Oriana L.'s user avatar
1 vote
1 answer
2k views

Non competitive inhibitors and Uncompetitive

Non competitive inhibitors affects the function of enzymes and slows the rate of reaction. Can I say the same for uncompetitive inhibitors ? Because Vmax decreases and it takes longer to form products ...
user307640's user avatar
1 vote
0 answers
25 views

Can methionine peptidase liberate selenomethionine?

Can methionine peptidase liberate selenomethionine from proteins? I'd be happy to know if any can that are active in humans, but am also especially curious about METAP2.
Rob F's user avatar
  • 79
-2 votes
1 answer
178 views

Please explain this notation MW around 9 MDa

I am a computational science student and was reading about the structure of Pyruvate dehydrogenase (PDH). link to article The article mentions "PDH is a large complex (MW around 9 MDa) consisting of ...
fireball.1's user avatar
2 votes
2 answers
104 views

Is there a hypernym for enzymes that "cut" other molecules?

I have searched on Google for a hypernym/umbrella term that encompasses all enzymes whose function is to cut other molecules, but I have yet to find such a term. The term I am looking for would ...
Hawkeye's user avatar
  • 598
1 vote
0 answers
31 views

Assay for Glycosyltransferase

I want to do an assay to see, if an ordered enzyme is active or not. It's a glucosyltransferase from S. mutans which hydrolyses sucrose into fructose and glucose. It then connects the glucose-monomers ...
Simon Pflug's user avatar
1 vote
1 answer
53 views

Can cognitive enhancement from exercise be replicated/replaced through prolonged standing?

Can cognitive enhancement from exercise be replicated/replaced through prolonged standing? Like, will BDNF be released from prolonged standing. I would prefer to use a standing desk than exercise (...
user avatar
1 vote
0 answers
24 views

What enzymes I shall use for preparing single cell suspension from cardiac tissue for flow cytometry?

Can anyone suggest which enzymes I shall use for preparing single cell suspension from cardiac tissue. I will be looking at both cell surface and intracellular antigens involving cardiomyocytes and ...
Sulail Fatima's user avatar
4 votes
0 answers
159 views

Are there any alternatives to the Epicentre product Plasmid Safe?

I need to remove any traces of linear DNA (both single and double stranded) from a ligation reaction while keeping circular DNA intact. Up to now, I have used Epicentre's Plasmid Safe to do the job. I ...
alec_djinn's user avatar
  • 3,068
0 votes
1 answer
103 views

Triosephosphate isomerase deficiency

Triose phosphate isomerase deficiency, a rare condition, is the only glycolytic enzymopathy that is lethal. This deficiency is characterized by severe hemolytic anemia and neurodegeneration. How can ...
JM97's user avatar
  • 4,786
9 votes
1 answer
2k views

Understanding Enzyme saturation curve

From the above picture it can be seen that, in the region "B" the activity of enzyme is not proportional to the substrate concentration. Why don't we achieve enzyme saturation linearly? Why do we go ...
JM97's user avatar
  • 4,786
0 votes
3 answers
162 views

Do different chiral centers on ligands cause different confirmational changes and effects in their target proteins?

Say pathogenic bacteriaA makes toxinA, which had D-amino acids instead of L-amino aids, does this difference in chirality cause a different conformational change in the receptor or enzyme, thus ...
Confusedbyeverything's user avatar
0 votes
2 answers
2k views

Is starch and glycogen digestion intra or extracellular?

Do humans have the enzyme for starch intracellular digestion? Also, do plants have the ability to digest Glycogen? Intra or extracellular, or both?
Water Butter's user avatar
6 votes
1 answer
78 views

What happens when you tag a protease with its own degradation tag?

I've been learning about the ClipXP, ClipAP, and Lon proteases. They are proteases from the AAA+ family, which seek out proteins tagged with certain peptide sequences, unfold them, and chop them up. ...
Cedar's user avatar
  • 183
5 votes
2 answers
4k views

Can enzymes catalyze thermodynamically unfavorable reactions?

Can biological enzymes catalyze thermodynamically unfavorable reactions? I read that an enzyme lowers the activation energy of a reaction by offering an alternative reaction pathway with a lower ...
Jonathan Smith's user avatar
4 votes
1 answer
4k views

How does aminoacyl-tRNA synthetase recognize different tRNAs?

There are about 20 aminoacyl-tRNA synthetases, one for each amino acid. Each aminoacyl-tRNA synthetase has a binding site that recognizes a specific amino acid, and other binding areas that recognize ...
Jonathan Smith's user avatar
5 votes
3 answers
7k views

Definition of Cofactor, Coenzyme and Prosthetic Group

This question arises from a student multiple choice question regarding whether certain inorganic ions present in certain enzymes (Cl− in catalyse and Zn2+ in carbonic anhydrase) could be classified as ...
vik1245's user avatar
  • 569
1 vote
0 answers
41 views

Energy cost of chewing vs production of enzymes

Consider a hypothetical case that you ingest a piece of starch. Which is more costly energetically 1) chewing + reduced amount of enzymes production needed or 2) sole production of all the enzymes for ...
y chung's user avatar
  • 344
4 votes
2 answers
4k views

Definition of a Katal (unit of enzyme activity)

I am very confused about what one 'Katal' actually is. From Wikipedia, "The katal is not used to express the rate of a reaction; that is expressed in units of concentration per second (or moles per ...
Meep's user avatar
  • 2,929
4 votes
2 answers
206 views

Is it a valid generalization that kinases catalyse reactions involving energy transfer and utilization?

The Wikipedia entry for kinase states that "a kinase is an enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules [such as ATP] to specific substrates". ...
DJG's user avatar
  • 337
2 votes
0 answers
690 views

Kinetics of allosteric regulation [duplicate]

I have found a diagram similar to the following one in my biology textbook. The diagram describes allosteric regulation. However, I do not quite understand why the maximum reaction rate $V_{max}$ is ...
HansMu158's user avatar
  • 121
12 votes
4 answers
7k views

Examples of enzymes working in reverse?

I have always been taught that enzymes can catalyze both the forward and reverse reaction, and will increase the reaction rate in both directions. I understand that the thermodynamics of the reaction ...
Arcadium's user avatar
  • 561
6 votes
1 answer
5k views

Enzyme kinetics; what happens at the peak of the Gibbs energy graph?

At the very peak, the energy is in a state of activation energy. Here, is the substrate just attaching to the enzyme, or is is substrate already breaking?
Kevin Ainge's user avatar
3 votes
1 answer
190 views

Sephadex column for alpha-amylase

I want to purify crude alpha-amylase with column chromatography. I am using a spehadex 75, But for some reason I can't find any information on how to make the slurry. I can quickly find tons of ...
LazorLord's user avatar
3 votes
3 answers
3k views

Is it wrong to consider an allosteric inhibitor a non-competitive inhibitor?

Supose Caspase-1 is allosterically inhibited. Since the inhibitor is not binding in the active site but instead in the allosteric binding site, can I conclude it is a non-competitive inhibitor?
Mauricio Mendes's user avatar
4 votes
2 answers
3k views

Identifying type of inhibitor from $K_m$ and $V_{max}$

Apparently it is possible to identify whether an inhibitor is competitive or non-competitive from graphs of substrate concentration (x axis) and rate of reaction (y axis). There needs to be a line ...
Mirte's user avatar
  • 328
1 vote
0 answers
276 views

Can a ribozyme be present on two different RNA molecules?

Suppose we have a ribozyme that consists of an 'enzyme' strand and a 'substrate' strand. (e.g. hammerhead ribozyme) Is it possible to have the enzyme strand of the ribozyme on one RNA molecule and ...
l..'s user avatar
  • 131
2 votes
0 answers
56 views

plausible science for why an enzyme breaks down a substrate better at 4 degrees rather than 20 degrees [closed]

An enzyme was found to have an optimal temperature of 20 degrees. The same enzyme in sheep liver extract was found to have an optimal temperature of 4 degrees. What are some of the factors that can ...
mary's user avatar
  • 21
11 votes
1 answer
5k views

In which direction does ATP synthase rotate?

I heard about the rotation of ATP synthase in a biochemistry course. The professor said it will rotate counterclockwise. Is that true? If so, what mechanism defines its direction?
latra's user avatar
  • 211
1 vote
0 answers
67 views

What is the oxidation state of iron at the photosynthetic reaction center?

Is the iron at the reaction centre in the $3^+$ or $2^+$ oxidation state? For instance, 1AIG is $2^+$ or, perhaps it will depend upon charge separation state? I checked the PDB: some are $3^+$ ...
latra's user avatar
  • 211
4 votes
1 answer
483 views

Betaine HCl stomach pH

It seems betaine HCL is often recommended for those suffering from "low stomach acid" -- which, as I understand, is having too high stomach pH for proper digestion (especially for proteolysis via ...
ManRow's user avatar
  • 355
20 votes
2 answers
2k views

What inactivates pepsin in infants?

In infants, rennin helps in digestion of milk. Pepsin is also present in their stomach. Why do infants need rennin for milk digestion, at the first place? Why does pepsin not act on the milk ...
user237650's user avatar
  • 3,268
2 votes
1 answer
472 views

Are Raf, MEK, and ERK MAP kinases?

I am trying to make sense of this diagram. Can Ras activate RAF or MAPKKK, or is RAF a MAPKKK, making MEK a MAPKK, and ERK a MAPK?
Savness's user avatar
  • 25
6 votes
1 answer
1k views

What happens to the enzymes produced by the digestive system?

Our digestive system produces a lot of enzymes and they help to catabolize the food, and after completing their work are they excreted out or as they are also made up of proteins are they catabolized ...
sreekara's user avatar
  • 739

1 2 3
4
5
8