Biochem E2 terms

noncompetitive inhibitor

(aka allosteric) inhibitor binds at the site separate from the active site, changing configuration preventing substrate binding

competitive inhibitor

inhibitor resembles substrate, competes for binding site

uncompetitive inhibitor

inhibitor binds to the enzyme-substrate complex, not the active site, binds to already formed enzyme substrates

irreversible inhibition

covalent modification of enzyme rendering it inactive

allosteric regulation

substrate binding at the active site is affected by the binding of a molecule at a different site

positive: opens active site

negative: closes active site

feedback control

end product of a metabolic pathway binds to an earlier enzyme in the same sequence to slow down/stop its own further production

positive: product enhances activity of first enzyme

negative: product inhibits the first enzyme

covalent modification

addition of a phosphate group on tyrosine/scrine/threonind residue triggers a conformational change in the structure. Actives/deactives enzyme

zymogens

synthesized in an inactive form (aka proenzyme), which has a longer protein segment that must be removed before the enzyme is active

genetic control

control amount of enzyme available in cell

enzymes

catalyze biochemical reactions

hormones

messengers that regular bodily functions

storage proteins

store essental substances for immediate availability

transport proteins

carry substances throught blood & through the cell membranes

structural proteins

support & maintain shape of cell

protective proteins

provide defense against invaders & protect from injury

contractile proteins

do mechanical work

glycoproteins

covalently bound carbohydrates (eg. form receptors on cell surface)

lipoproteins

covalently bound to lipids (eg. transport cholesterol through blood)

metalloproteins

metal ion (trace minerals) for structure stabilization or catalytic function

phosphoproteins

covalently bound phosphate groups used to activate or deactivate a protein or provide binding sites for protein attachment

hemoproteins

contain heme groups/porphyrin rings (eg. oxygen transporters, drug metabolizing enzymes, energy producing enzymes)

nucleoproteins

contain ribonucleic acids (ribosomes used in protein synthesis)

enzyme

a biological catalyst (protein or RNA). enzyme ends in - ase

Substrate

reactant of an enzyme catalyzed reaction

turnover number

number of substrate molecules that are converted to product over a given period of time

cofactor

nonprotein substance that binds to the protein and is required for catalysis

coenzyme

organic cofactors typically found in redox enzymes

apoenzyme

protein minus its cofactor/coenzyme

holoenzyme

catalytically active enzyme (apoenzyme with its cofactor/coenzyme)

active site

pocket in enzyme where catalysis takes place

proximity effect

bring reactants together

orientation effect

hold reactants at the required distance and orientation for the reaction

energy effect

lower activation energy by inducing a strain on the bonds of the substrate

catalytic effect

provide acidic, basic, and other types of functional groups that are required for catalysis

oxidoreductases

catalyze redox reaction

Subclass: hydrogenases - removes 2 H atoms from a substrate to form a double bond

tansferases

transfer of a functional group (amino acid/phosphoryl) between substrates

Subclass: kinases - transfers a phosphoryl group & transaminase - transfers an animo group

hydrolases

catalyze hydrolysis of substrates (water lysis)

Subclass: hydrolyze… lipases - ester bonds in lipids & proteases - peptide bonds & nucleases - phosphate ester bonds in DNA/RNA & amylases - 1,4 glycosidic bonds in amylose

isomerases

catalyze the isomerization of substrate (rearranges bonds)

lyases

catalyze the elimination of a functional group by forming or breaking a double bond

ligases

catalyze bond formation couple with ATP hydrolysis (which provides the energy of the bond formation)

Intramolecular Bonds

Covalent Bond, amino acids, peptides & disulfides

Electrostatic interactions - salt bridges

non-covalent, dipole, stabilize 2/3/4 protein structure

Hydrogen bond

non-covalent, donors (O-H & N-H) and acceptor (O & N)

Van Der Waals Forces

non-covalent, between all atoms

Hydrophobic effect

exclusion of water by non-polar groups causes proteins to fold