enzymes n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Enzymes PowerPoint Presentation
Download Presentation
Enzymes

Loading in 2 Seconds...

play fullscreen
1 / 12

Enzymes - PowerPoint PPT Presentation


  • 137 Views
  • Uploaded on

Enzymes. Important protein complexes. Background. Activation Energy: the energy needed to start non-spontaneous chemical reactions Catalyst: a compound that decreases activation energy and speeds the reaction. Catalysts are not consumed in the reaction so they are reuseable. Enzymes.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Enzymes' - fred


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
enzymes

Enzymes

Important protein complexes

background
Background
  • Activation Energy: the energy needed to start non-spontaneous chemical reactions
  • Catalyst: a compound that decreases activation energy and speeds the reaction.
  • Catalysts are not consumed in the reaction so they arereuseable
enzymes1
Enzymes
  • Are biological catalysts
  • Belong to a class of proteins
  • Speed up reactions by decreasing the activation energy barrier
  • Each enzyme is substrate specific (molecular recognition)
induced fit model of enzyme reaction
Induced-Fit Model of Enzyme Reaction
  • The active site is a restricted area (often a surface groove) to which the substrates bind.
  • The active site is only a small fraction of the enzyme and contains amino acids with active side chains
  • An enzyme’s specificity is due to compatible fit between the shape of the substrate and the active site (governed by 3° structure)
  • Bonding involves non-permanent bonds (H-bonds, Ionic bonds, etc.)
induced fit model
Induced-Fit model
  • The substrate(s) entering the active site induces a deformation (slight change in shape) so that the functional groups in the active site fit more closely around the substrate(s)
  • Bonds are formed or broken because the flexing weakens and strains the chemical bonds in the substrate(s) making it more reactive
  • Bonds may be moved to a more stable arrangement
slide6

http://www.cas.muohio.edu/~wilsonkg/old/gene2005/syllabus_F03_23.jpghttp://www.cas.muohio.edu/~wilsonkg/old/gene2005/syllabus_F03_23.jpg

lock and key model
Lock and Key Model
  • The lock is the enzyme and the key is the substrate
  • Only the correctly sized key (substrate) fits into the key hole (active site) of the lock (enzyme).
  • Smaller keys, larger keys, or incorrectly positioned teeth on keys (incorrectly shaped or sized substrate molecules) do not fit into the lock (enzyme).
  • Only the correctly shaped key opens a particular lock.
factors that affect enzyme activity
Factors That Affect Enzyme Activity

I. Environmental conditions:

  • Optimal temperature allows the greatest number of molecular collisions without denaturing
  • Optimal pH (usually 6-8) high acid denatures most enzymes (except pepsin at pH 2 in the stomach)
  • Salt usually dissociates in aqueous solutions to form ions. Inorganic ions interfere with the 3° structure (ionic bonds)
factors that affect enzyme activity1
Factors That Affect Enzyme Activity

II. Cofactors:

Many enzymes need non-protein helpers for catalytic activity

(bind to active site)

  • Some are inorganic (metals like Zn, Cu, or Fe)
  • Some are organic (coenzymes that are made from vitamins)

III. Inhibitors:

prevent enzyme activity

  • Competitive inhibitors resemble the substrate and block active site
  • Non-competitive inhibitors bind outside the active site and change the enzymes shape so the active site is non-receptive
    • Some inhibitors are harmful to the organism (DDT, antibiotics)
    • Others are necessary for metabolic control
enzyme function
Enzyme Function
  • http://www.youtube.com/watch?v=PILzvT3spCQ
slide12

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/biobookenzym.htmlhttp://www.emc.maricopa.edu/faculty/farabee/BIOBK/biobookenzym.html