A2- Proteins and Enzymes

NH2

COOH

a ion with separate positively and negatively charged groups (overall neutral charge)

isoelectric point (usually around pH 6)

COOH dissociates, forming COO-

NH2 gains H+, forming NH3+

sequence of amino acids

Hydrogen bonds cause B-pleated sheets or a-helix to form

when NH2 groups are on the same side

hydrogen, ionic and disulfide bonds make 3D shape

protein-based biological catalyst, that speeds up rate of reaction by lowering Ea

• a specific active site that must fit and have intermolecular forces with a specific substrate. • This promotes the movement of electrons which lowers Ea

so specific that only one out of a pair of enantiomers will bind to the enzymes active site

changing temp and pH

primary: peptide bonds between amino acids, the specific sequence of amino acids secondary: H bonds between amino acids in same chain alpha helix: Hydrogen bonds between peptide bonds every 4 amino acid residues, on the same chain Beta pleated sheet: protein folds, hydrogen bonds between parallel peptide bonds tertiary: ionic between COO- and NH2 in R groups disulfide; S-S hydrogen, BETWEEN R GROUPS VdWs: Between alkyl side groups

conc HCl, slow

ninhydrin

as some amino acids have similar Rf values in different solvents