Lecture 10 Flashcards
(36 cards)
What are the 3 cellular energy considerations
- ATP (adenosine triphosphate)
- Exergonic vs. Endergonic reactions
- Change in free energy
What is the role of enzymes?
catalyze biochemical reactions in a living organism, usually a protein
What are enzymes made of?
Enzymes are made from living cells, but could still remain and function, once the cells from which they were made were broken down
What are proteins manufactured from
manufactured from genes through the process of protein synthesis
Enzyme size and fit
Enzymes are larger than the substances (substrates) upon which they act. Enzymes have a location known as the active or catalytic site where the substrates will fit.
Catalysts
improve the efficiency of reactions. They speed up reactions that would otherwise occur in nature very slowly without these enzymes.
How do enzymes help metabolism in cells? 2 ways
a. Enzymes lower the activation energy that is necessary to initiate a reaction.
b. Enzymatic reactions allow for energy to be released in increments, thus allowing for a more
efficient capture and usage of the energy.
Can enzymes be recycled?
Yes
active or catalytic site
Enzymes come into a close and
intimate 3D contact with their substrates at the active or catalytic site- this specific interaction is
sometimes described by a lock and key type hypothesis and as complimentary steric specificity
allosteric sites
Enzymes have sites for chemical bonding away from the active or catalytic site. These sites are
known as allosteric sites.
Competitive inhibitors
act to compete with the substrate at the active site
non-competitive inhibitors
act at allosteric sites
apoenzyme
protein portion
cofactor
nonprotein portion
The apoenzyme and the cofactor together make up
the complete and active whole enzyme known as a holoenzyme
The cofactor can be
a metal ion, or if it is a low molecular weight and complex organic molecule it is called a coenzyme
Metal ion such as? bind where?
what do they do?
such as iron, zinc, magnesium and calcium will bind at allosteric sites
Metal ion cofactors will bind to allosteric sites and alter the configuration of the active sites.
Coenzymes bind?
will bind at the active or catalytic site
Coenzymes assist the enzymes by and are derived from?
by accepting atoms removed by the substrate or
by donating atoms required by the substrate. Many coenzymes are derived from vitamins.
NAD (nicotinamide adenine dinucleotide)
transfers hydrogen pairs (2H) and is derived from
the B complex vitamin, niacin
FAD (flavin adenine dinucleotide)
transfers hydrogen pairs (2H) and is derived from the B
complex vitamin, riboflavin.
CoA (coenzyme A)
transfers a 2 carbon unit (acetyl group) and is derived from the B complex vitamin, pantothenic acid
Folic acid-transfers carbon
derived from the vitamin called THFA (tetrahydrofolic acid)
PABA (para-aminobenzoic acid)
Bacteria uniquely need PABA (para-aminobenzoic acid) to make folic acid. Antibiotics known as sulfanilamides will block the activity of PABA, preventing the synthesis of folic acid and thereby inhibiting bacterial metabolism