Enzyme Part 1 Flashcards
(38 cards)
> Greek word en
means “in”
> zyme
which means “yeast”
> is an organic compound that act as a catalyst for a biochemical reaction; increases rate of reaction butare not changed in the process
water-soluble, globular proteins
Features:
a) Enhance reaction rates (pH 7.4 and 37°C). An enzyme catalyzed reaction can be 106 to 1012 times faster than uncatalyzed reaction
b) Enzymes are very specific.
Enzyme
> Features:
a) Enhance reaction rates (pH 7.4 and 37°C). An enzyme catalyzed reaction can be 106 to 1012 times faster than uncatalyzed reaction
b) Enzymes are very specific.
STRUCTURE OF ENZYME
an enzyme composed only of protein.
• simple enzyme
an enzyme that has a nonprotein part in addition to the protein part.
conjugated enzyme
is the protein part of a conjugated enzyme
> apoenzyme
is the nonprotein part of a conjugated
enzyme
cofactor
is the biochemically active conjugated enzyme produced from an apoenzyme and a cofactor
Apoenzyme + cofactor = holoenzyme
holoenzyme
Why do apoenzymes need cofactors?
• A cofactor is a non-protein chemical compound that is required for the protein’s biological activity.
• Cofactors can be considered “helper molecules” that assist enzymes in their action. Cofactors can be ions or organic molecules (called coenzymes).
is a small organic molecule that serves as a cofactor in a conjugated enzyme.
Coenzyme
Inorganic ion cofactors include zinc, magnesium, manganese, and iron; chloride occasionally acts as a
Cofactor
- It is bound tightly to the enzyme and is not dissociated even after several extensive steps of purification.
Metallo-enzymes
are the focal points for nomenclature.
type of reaction catalyzed and substrate
is the reactant in an enzyme-catalyzed reaction; it is the substance upon which the enzyme”acts”
substrate
Few enzymes exist in their inactive form called.
proenzymes or zymogens
- become active after prior modification in its structure by certain agents. Many times the active form of enzyme acts on zymogen and catalyzes its conversion into active form - process called AUTOCATALYSIS
Zymogens
PROPERTIES OF ENZYMES
- special pocket or cleft within the enzyme molecule
- contains amino acids side chains that participate in substrate binding and catalysis
Active sites
- Highly efficient (103
- 108) times faster than uncatalyzed reactions
Catalytic efficiency
- highly specific, interacting only with one or a few substrates and catalyzing only one type of chemical reaction
Specificity
- some enzymes require molecules other than proteins for enzymatic activity
- Holoenzymes refers to the active enzymes with its nonprotein component, whereas the enzyme without its nonprotein moiety is termed an apoenzyme and is inactive.
If the nonprotein is a metal ion (Zn2+ or Fe2+), it is called a cofactor
If it is a small organic molecule, it is termed as coenzyme. - Coenzymes that only transiently associate with the enzyme are called cosubstrates.
- Cosubstrates dissociate from the enzyme in an altered state. (ex. NAD+)
Holoenzymes
- Enzyme activity can be regulated, that is, increased or decreased, so that the rate of product formation responds to cellular need.
Regulation
- Many enzymes are localized in specific organelles within the cell. Such compartmentalization serves to isolate the reaction substrate or product from other competing reactions. This provides a favorable environment for the present in the cel into purpose tipathways of enzymes
Location within the cell
requires a coenzyme that is oxidized or reduced as the substrate is reduced or oxidized.
Lactate dehydrogenase is an oxidoreductase that removes hydrogen atoms from a molecule.
Oxidoreductase
