What is Enzymes: Definition and 36 Discussions

Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called enzymology and a new field of pseudoenzyme analysis has recently grown up, recognising that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties.Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts are catalytic RNA molecules, called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures.
Like all catalysts, enzymes increase the reaction rate by lowering its activation energy. Some enzymes can make their conversion of substrate to product occur many millions of times faster. An extreme example is orotidine 5'-phosphate decarboxylase, which allows a reaction that would otherwise take millions of years to occur in milliseconds. Chemically, enzymes are like any catalyst and are not consumed in chemical reactions, nor do they alter the equilibrium of a reaction. Enzymes differ from most other catalysts by being much more specific. Enzyme activity can be affected by other molecules: inhibitors are molecules that decrease enzyme activity, and activators are molecules that increase activity. Many therapeutic drugs and poisons are enzyme inhibitors. An enzyme's activity decreases markedly outside its optimal temperature and pH, and many enzymes are (permanently) denatured when exposed to excessive heat, losing their structure and catalytic properties.
Some enzymes are used commercially, for example, in the synthesis of antibiotics. Some household products use enzymes to speed up chemical reactions: enzymes in biological washing powders break down protein, starch or fat stains on clothes, and enzymes in meat tenderizer break down proteins into smaller molecules, making the meat easier to chew.

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  1. samy4408

    Medical Hello, I found a weird sentence in a book about enzymes....

    Hello ! We all now that enzymes lower the activation energy by creating both covalent bonds and week non covalent bonds , in this book , about how the enzyme lower the activation energy using covalent bonds they said : this sentence is not compatible with a basic principle that i learned in...
  2. samy4408

    Medical Question about reactions in biochemistry

    we assume that we have an exergonic reaction , a substrate going to a product , is the negative ΔG′° the principal reason that the equilibrium favors the product (there is more product than substrate at equilibrium )?, or it is not and that depends on other factors? , thanks .
  3. D

    Chemistry Reference book on catalytic mechanisms of enzymes

    Hi everyone, I'm curious if anyone knows of a reference book on enzymes that discusses each enzyme's catalytic mechanism(s). I've consulted several books that explain the different categories of enzymatic catalysis but I'm looking more for an encyclopedic reference that explains such...
  4. Mr Green T

    Can machine learning design living organisms?

    Pop culture interpretation: Machine learning reveals recipe for building artificial proteins Actual Study: Evolution-based design of chorismate mutase enzymes Using Boltzmann machine learning to design enzymes with evolutionary compatible statistical constraints is possible now. How much...
  5. YoungPhysicist

    Producing TRPs: Is Genetically Modified Fungi an Option?

    Transient Receptor Potential cation channels, or TRPs, are special proteins on us which can detect temperature changes or special chemical substances. Like menthol to TRPM8 , or Capsaicin to TRPV1. Is there any current research that are trying to produce these sort of receptors via...
  6. Psinter

    Can DNA reveal a person's enzyme deficiencies or lack of enzymes?

    Does the human DNA contain information that could, combined with other data, tell what kinds of chemicals will their digestive system process or not? For instance, there are people that have hereditary fructose intolerance (not to be confused with fructose malabsorption). Is such a lack of an...
  7. ORF

    Medical Why doesn't the intestine digest itself?

    Hello I have read this article about why doesn't the stomach digest itself https://www.scientificamerican.com/article/why-dont-our-digestive-ac/ but also during the digestion along the small intestine, there are enzymes. How does the small intestine defend against these enzymes? ( I suppose...
  8. Emmanuel74

    Extracting Enzymes from Fruits, Vegetables, and Grains

  9. A

    2 Biochemistry MC Questions - Protein Structure, Enzymes

    1. A substrate molecule may be bound to the active site of an enzyme by all of the following EXCEPT A. Hydrogen Bonds B. Peptide Bonds C. Ionic Bonds D. Van der Waals Interactions E. Hydrophobic Interactions 2. Which of the following components is the most important in determining the 3-D...
  10. Aafia

    What is the effect of temperature on enzymes in poiklotherms

    Since enzymes have particular temperature on which they are able to catalyze the reaction and increasing the temperature above optimum can damage enzymes then how does poiklotherms survive as they change their body temperature according to environment unlike homoiothems. Also wouldn't their...
  11. P

    Why catalysts affect forward and reverse reactions?

    Based on the very basic understanding on enzymes I have gained from Year 12 Biology and Chemistry, I don't undesrtand why the enzymes specific shape also helps the reverse reaction. I guess my trouble would be due to the simplified diagrams I've seen from Biology, where only the forward reaction...
  12. J

    How do pH and enzymes interact in a lab setting?

    Homework Statement Hi just a quick question. I was doing a lab report and this enzyme is supposed to work between the pH of 6.7 and 7. So I had solution of .0125 N and I said OK just subtract this from 7.0 and say that is the new Ph. So for instance 7.0 -0.125 = 6.98 I said OK this is...
  13. A

    How Can I Denature Enzymes to Preserve Frozen Food Longer?

    I need to preserve frozen food (uncooked) as long as possible. One of the damages caused by long term storage would be enzymes in the food itself. If it is a raw product, i can't exactly heat it up to denature the enzymes. Can i however, use other methods? I was thinking electricity...
  14. I

    Do enzymes tranfer energy to break substrates?

    I'm new to the subject and i have an intuition that during the time the substrate and the enzyme are together energy is transferred to the substrate (from the enzyme) to break the bonds and to release the substrates energy*. But alas i have been met with opposition to this understanding...
  15. T

    Stoichiometry with enzymes and temperature

    I'm currently doing an EEI with catalase and hydrogen peroxide. I'm just wondering about the effects of increasing the temperature of the catalase and h2o2. For example, if I get 50mL of oxygen produced when both are at 40°C and the reaction occurs for 8 seconds. If I decrease the temperature to...
  16. C

    What Does It Mean for an Enzyme to be Inactive or Denatured?

    enzymes are considered inactive at low tempertaures, and denatured at high temps.both these terms have different meanings, with inactive meaning enzyme having "low activation energy"and denatured meaning the enzyme is destroyed. when an enzyme is inactive, it does not lower the activation...
  17. H

    Enzymes, Where can i get LIPL-4

    Where can i get LIPL-4
  18. Z

    Do DNA Viruses Contain Enzymes?

    I know that some RNA viruses do but do DNA viruses have enzymes? as a general rule would it be right to say that most viruses do not have enzymes. thanks
  19. S

    Quick questions on restriction enzymes?

    Hello everyone, [PLAIN]http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/R/RestrictionEnzymes.gif 1. Restriction enzymes cut only sugar phospahte bonds right. So in the formation of sticky bonds for example in BamHl, how does the hydrogen bonds between the molecules break. When sugar...
  20. A

    Enzymes contribute energy to a reaction?

    Everything I read says enzymes are organic catalysts and do not supply energy for chemical reactions. My understanding is they speed up reactions by providing alternate pathways that have a lower activation energy. A quiz I took asked "What type of energy do enzymes contribute to chemical...
  21. L

    Effect of Temperature on enzymes

    Homework Statement I have a lab tomorrow and it says it my lab book, and it says to add distilled water to a reaction consisting of the substrate then another one with the enzyme...i don't get it what's the purpose of distilled water...i really don't understand. Thanks.. Homework Equations The...
  22. Y

    Some enzymes are good, some act poorly what are charateristics of a good enzyme?

    As in Title, help much appreciated! thanks
  23. D

    Cooperativity & Glycolysis: Regulation of Enzymes

    is it true that cooperativity is rare in enzymes with tertiary structure and that Glycolysis is inefficient and therefore rarely found in present day organisms i am not sure.. but iwas also wondering that a particular enzyme is likely subject to only a few forms of the regulation we...
  24. S

    Allosteric activity in enzymes.

    I've always wondered how enzymes could tell the difference between too much substrate and too little substrate to initiate allosteric activities, my teacher tells me that its kinda like collision theory in chemical bonding. That would make sense because if there's too much product, then some of...
  25. V

    Advantages of multiple restriction enzymes for cloning

    why would utilizing duo restriction enzymes for cloning be better then just one? ( e.coli to pBluescript II )
  26. M

    Enzymes in dehydration synthesis/condensation reaction and hydrolysis?

    enzymes in dehydration synthesis/condensation reaction and hydrolysis?? what is the name of the enzyme that aid dehydration synthesis/condensation reaction and the enzyme that aid hydrolysis? thank you very much
  27. B

    Can DNA repair enzymes reverse oxidative damage and combat aging?

    Are there any known enzymes that will fix oxidative dna damage without correcting mismatched bases? Any enzymes that are thought to work like that? thanks
  28. B

    Where to Buy Enzymes? Providers & Suppliers

    Does anyone know commercial providers of enzymes ?
  29. B

    Methanotrophic bacteria / enzymes

    Dear all ! Does anyone have experience with methanotrophic bacteria ? The background of my question: I am trying to explore a new pathway for the reaction methane to methanol. One can basically think of two approaches: a) chemically via classic catalysts, b) biologically via enzymes or...
  30. B

    Life Based On Enzymes Question?

    Homework Statement Formulate your own definition of what is meant by living organisms. *I also posted the lab which this question is asked on in a thread called "Enzyme Lab." Homework Equations The Attempt at a Solution I don't think that this answer is right but don't know...
  31. F

    Explanations of variations in errors with regards to enzymes

    Hello, how can large variation between sets of different Ph results be scientifically explained, i am investigating the effects of Ph on enzyme activity, there are small error bars in my results between ph1,2,3,4 &5 however there is larger error bars between ph-6,7,8,9 & 10. there's an...
  32. F

    Understanding Enzymes: Error Bars, Substrate Drops, and Insulin Structure

    hello every 1, i have a few questions -i'd like to know what error bars are & how did i plot them on a graph? -can some one please give me a scintific explanation to why small drops of substrate are introduced into a enzyme when trying to find its activity, all i know is that if all the...
  33. P

    Enzymes & Catalysts: True or False?

    Which of the following are true about the following reaction ? O3 + O --> 2 O2 a) The direct reaction breaks down O3 at a slower rate than the same reaction where Cl is used as a catalyst b) When Cl is used as a catalyst, it functions as an intermediate in...
  34. R

    Enzymes Inside Cells: What is Their Role?

    can somebody help me with the following question? What is the role of enzymes inside cells? please help it would be much appreciated :confused:
  35. A

    How do enzymes lower the free energy of activation?

    Hey guys; I've a question. How do enzymes lower the free energy of activation? My thinking is that the enzyme binds, and when it binds it alters the shape of whatever it binds to, and the altered shape is energetically favored to the unaltered shape for the reaction. This is purely...
  36. M

    Restriction Enzymes: Interference & Impacts on DNA

    I'm wondering if, when put into the DNA together, two different restriction enzymes will interfere with each other, and how. Will two different restriction enzymes cut the DNA as they each would separately, since they are specifically formed to react with it and not each other, or would they...