Introduction to Protein Structure Flashcards
What are the 5 protein structures?
Primary (sequence)
Secondary (local folding)
Tertiary (long-range folding)
Quaternary (multimeric organization)
Multiprotein complexes
Proteins are composed of
Amino Acids
What differs between amino acids?
The R-group
They all have a C bonded to an H group, an amino group (NH2) and a carboxyl group (C(=0)-OH) + the R group
What are the major categories of amino acids?
Acidic (negative charge), basic (positive charge), uncharged polar, non-polar
Polar charged (acidic or basic) are important for…
enzymatic function and the structure of a protein.
Uncharged polar amino acids are important for…
they tend to form H-bonds and interact with water (may be an outside protein)
nonpolar amino acids…..
Are usually part of the hydrophobic inner core of protein
- hydrophobic forces push them to the middle into the so-called hydrophobic core
- associated with the lipid bi-layer
Messenger RNA (mRNA)
Its primary function is to carry genetic information from the DNA in the nucleus to the ribosomes in the cytoplasm, where proteins are made.
It is going to specify which AA is being used by the ribosome.
Ribosomes
The ribosome is a crucial cellular structure that plays a central role in protein synthesis. Its primary function is to translate the genetic information carried by mRNA (messenger RNA) into a specific sequence of amino acids to form a protein.
Disulphide bonds
very strong and affected by redox conditions
Formed between Cysteine AA, between the same or different strands.
Don’t form the structure of proteins but can contribute a lot to it; act like a staple to hold protein shape
Peptide bonds
AA linking
Carboxyl groups react together with the amino group of an incoming acid (loss or 1 H2O)
Covalent
Also called a condensation reaction
N-terminus
Amino end of AA chain
C-terminus
Carboxyl end of AA chain
Directionality of polypeptides
N - C
Peptide backbone
CCN - CCN -CCN
Once in a polypeptide chain, amino acids are…
called residues
Secondary folding
Occurs naturally into 2 conformation;
- Alpha-helix
- Beta Sheet
Alpha Helix
R groups NOT involved in folding
Common secondary structure
H-Bonds form between the N that’s on the peptide backbone and the O
- Hydrogen bonds happening amongst atoms that are involved in the peptide bond (very local)
