enzymes
DESCRIPTION
Enzymes. Characteristics of Enzymes. Proteins Catalysts Speed up chemical reactions without being used up. Structure. An enzyme’s shape is very specific. If changed, we call it… DENATURED Can no longer catalyze reactions What kinds of things do you think could denature a protein?. - PowerPoint PPT PresentationTRANSCRIPT
Enzymes
Characteristics of Enzymes1. Proteins2. Catalysts
a. Speed up chemical reactions without being used up
Structure1. An enzyme’s shape is very specific.
1. If changed, we call it…
DENATURED–Can no longer catalyze reactions– What kinds of things do you think could
denature a protein?
Denaturation
a. Disruption of protein structure by1. Heat: Break apart H bonds and disrupt
hydrophobic attractions 2. Acids/ bases: Break H bonds between polar
R groups and ionic bonds3. Heavy metal ions: React with S-S bonds to
form solids4. Agitation: Stretches chains until bonds
break
Applications of Denaturation
a. Hard boiling an eggb. Wiping skin with alcohol swab for injectionc. Cooking food to destroy E. coli
How do enzymes work?
1. Lower Activation Energy to speed up rates of reactiona. Reactions require energy to begin…
enzymes lower the amount of energy required.
Naming1. Often end in “–ase” 2. Prefix refers to what substance it causes
to reacta. Examples: maltase, sucrase,
protease, carboxypeptidase
Catalyzing Process
1. Unique 3-D shape determines which chemical reaction it catalyzes
2. Important Vocab:a. SUBSTRATE: A specific reactant that
an enzyme acts on.
2. Important Vocab (cont.):b. ACTIVE SITE: the region of the enzyme
where the substrate will bind
3. The enzyme and substrate bond to form the enzyme-substrate complex
substrate
enzyme
Active site
Enzyme-substrate complex
Lock and Key Model
+ +
E + S ES complex E + P
S P
P S
Enzymes are very specific!
1. An enzyme’s optimal temperature =highest rate of reaction
a. Most human enzymes work best at 35-40 ºC.
Optimum temperature
ReactionRate
Low High Temperature
TEMPERATURE
WATCH OUT!!!If the temperature gets too high, the enzyme may be
denatured!
pH (Acid/Base)
• The enzymes in your stomach will not work in your blood.
• Most of your enzymes work best around a neutral pH
Rate of Reaction
• enzyme lab…
Substrate ConcentrationIncreasing substrate concentration increases
the rate of reaction up to a certain point.a. Limited by enzyme concentration, why?
a. Maximum activity reached when all of enzyme combines with substrate
Substrate Concentration (cont.)
Maximum activity
ReactionRate
substrate concentration
Enzyme Inhibition
1. Inhibitors: cause a loss of catalytic activitya. May be competitive or noncompetitive
2. Competitive Inhibitiona. A competitive inhibitor
1. Has a structure similar to substrate2. Occupies active site
a. “Competes” with substrate for active site
3. Effects can be reversed by increasing substrate concentration
Competitive Inhibition Image
3. Noncompetitive Inhibition
a. A noncompetitive inhibitor1. Binds to the enzyme (not at active site) &
changes the shape of enzyme & active sitea. Substrate cannot fit altered active site
2. Effect is not reversed by adding substrate
Noncompetitive Inhibition Image