MCB Lec 9

the study of reaction rates that are catalyzed by a purified enzyme

standard free energy change at pH of 7

detemines whether reaction is spontaneous

reaction at equilibrium

= 2.478ln +Keq

very high temperature cause denaturation of proteins, lower enzyme activity

lot of enzymes require the catalytic residues to be in correct ionization state, if not can impact enzyme activity (changes in pH)

A-+ B ---> A+B-

A-B + C ---> A+ B-C
enzymes tranferring group from one donor to acceptor

A-B + H2O ---> A-H + B-OH
catalyse the hydrolysis of various bonds

A-X + Y-B ---> A=B + X-Y

cleaves C-C C-N C-O bonds with hydrolysis or oxidation
molecule is eliminated and forms a new double bond

A-X + B-Y --> A-Y + B-X
catalyzes changes within 1 molecule
PDIs and PPIs

A + B ---> A-B
ATP

an additional chemical component other than amino acid residues that is required for the activity of some enzymes

cofactor that is a complex organic molecule

a coenzyme that is tightly or even covalently bond to the enzyme protein

a complete catalytically active enzyme together bound with its coenzyme and/or metal ions

the protein part of the holoenzyme

substrate matches perfectly to enzyme site

once the substrate binds the enzyme around it molds to fit.

a proton is transferred between the enzyme and substrate

a covalent bond forms between the enzyme and substrate

when reaction has more than one substrate via favorable orientations

Metal ion can function and facilitate the formation of the nucleophile or serve as an electrophile

enzyme donates a proton to the substrate

enzyme abstracts a proton from the substrate

Binding: binds to substrate
Positioning: Binding places the sugar bond to be split near two key lysozyme residues, Glu35
and Asp52.
Activation: ASP 52 acts as a nucleophile and forms a temp bond with sugar (covalent catalysis)
Involvement of water: : Glu35, now negatively charged, makes water a better nucleophile.
Water's OH- joins the sugar's carbon, and H+ joins Glu35 (general base catalysis).
5. Hydrolysis: The sugar bond between sugar units D and E is hydrolyzed, and the enzyme returns
to its original state.