amino acids, pep and proteins Flashcards
amino acids
molecules that contain two functional groups, and amino group and a carboxyl group. for an alpha Amino acid, to the alpha carbon, there are two other groups attached to it, a hydrogen atom and a side chain/R group.
proteinogenic amino acids
20 alpha amino acids encoded by the human genetic code
amphoteric species
AAs for example,
can either accept a proton or donate a proton, spends on the pH of their environment
zwitterions
dipolar ions
has both a positive chg and neg chg
the charges neutralize one another
exist in water as internal salts
peptides
composed to aa subunits, which are sometimes called residues
dipeptides
consist of two animo and residues
tripeptides
consists of three amino acid
oligopeptide
relatively small peptides (up to about 20 peptides)
longer chains are called polypeptides
peptide bond
residues in peptides are joined together thru this, which is a specialized form of an amide bond that forms between the coo- group of one AA and the nh3+ grp of another aa
sequencing
laboratory technique that can determine the primary structure of a protein using the dna that coded for hat protein, although it can also be done from the proton itself
alpha-helices
rodlike structure in which the peptide chain coils clockwise around a central axis and is stabilized by INTRAMOLECULAR H BONDS BTWN CARBONYL O AND AMIDE H 4 RESIDUES DOWN THE CHAIN
important component in the structure of keratin (fibrous structural protein found in human hair, skin, nail)
beta-pleated sheets
parallel or anti-parallel
the peptide chains lie alongside one another, forming rows or strands held together by INTRAMOLECULAR H BONDS WTN CARBONYL O ON ONE CHAIN AND AMIDE H ON ADJACENT chain
to accommodate as many h bonds as possible, they are pleated or rippled
fibroin, primary protein component of silk fibers
due to its __ __ structure, ___ will introduce a kink in the peptide chain when it is found in the middle of an alpha helix, so they are rarely found in them, except in ones that cross the membrane. also rare in middle of pleated sheets, so it is found in the turns between chains in beta sheet and start of alpha helix
rigid cyclic
proline!
fibrous proteins
collagen
structures that resemble sheets or long strands
globular proteins
myoglobin
tend to be spherical
disulfide bonds
bond that forms when two cysteine molecules become oxidized to form cystine
create loops in protein chain
the more there are, the curlier your hair is!!
requires the loss of two protons and two electrons (oxidation)
molten globules
intermediate states in protein folding, where basically the secondary structures form first, then hydrophobic interaction and H bonds cause the proton to “collapse” into its proper form
denaturation
when a proton loses its tertiary structure, so it loses its function
solvation layer
formed by the solvent molecules when a solute dissolves in a solvent around that solute
more disorder means that it is un/favorable (?) and a __ (non/spontaneous? process)
unfavorable
non spontaneous
role of the formation of quaternary structures
more stable by further reducing the surface area of the protein complex
can reduce the amt of DNA needed to encode the protein complex
can bring catalytic sites close together, allowing intermediates from one reaction to be directly shuttled to a second reaction
can induce COOPERATIVITY, OR ALLOSTERIC EFFECTS
why do hydrophobic residues tend to occupy the interior of a protein while hydrophilic residues tend to accumulate on the exterior portions
increases entropy by allowing water molecules on the surface of the proton to have more possible positions and configurations. the positive delta S makes delta G <0, stabilizing the protein
conjugated proteins
derived part of their function from covalently attached molecules called prosthetic groups (which can be organic molecules or metals)
lipoproteins
proteins with lipid prosthetic groups
