Structure of proteins I Flashcards
functions of proteins
catalyst for reactions
regulate gene transciption
mediatory of immune response
components of CT
what are the structure and function of a protein determined by
amino acid sequence of its polypeptide chain
feature of alpha-amino acid
central alpha-carbon
alpha carbon is asymmetric (except glycine)
what type of amino acids are found in mamalian proteins
L-amino acids
what amino acid is a secondary amine
proline
what groups is an alpha carbon covalently bound to
alpha amine
alpha carboxylic acid
hydrogen
R group
what gives each amino acid its unique chemical and physical properties
the R group
zwitterion
molecule having both positive and negative charges
what are the non polar aliphatic amino acids
glycine, alanine, valine, leucine, isoleucine, methionine, proline
where are the non-polar aliphatic amino acids typically found
in interior of globular proteins
what is unique about methionine
contains sulfur
what are the aromatic amino acids
phenyalanine
tyrosine
tryptophan
what type of property do aromtic amino acids ahve
hydrophobic
why does tyrosine ahve soem polarity
because of the OH group
why is tryptophan slightly polar
ring nitrogen
what are the pola runcharged amino acids
serine threonine cysterin asparagine glutamine
where are the polar, uncharged amino acids found
interior and exterior of proteins
what do polar, uncharged amino acids readily form
hydrogen bonds
what is unqiue about cysteine
contains sulfur, readily forms disulfie bridges
the hydroxyl groups of serine and threonine serve as what
phosphate acceptors in protein kinase reactions
what are the amino acids with ionizable side chains
aspartate gluatmate
what are asp adn glu considered to be
acidic amino acids
what are the basic amino acids
lysine, arginine, histidine
what carries a negative charge at physiological pH
asp adn glu
what carries a postive charge at physiological pH
arg and lys
what type of charge does histidine carry at physiological pH
can be positive or uncharged
peptide bonds
linkages that connect amino acids to form polypeptide chains
what are peptide bonds formed by
dehydration reaction
what is the confirmation of a peptide bond
planar
what is the primary structure of a protein
amino acid sequency
what are the ends of a polypeptide chain
free amino group, free carbosylate group
how are peptide sequences written
from N terminus to C terminus
What are 2 ways we can view protein structures
X ray cystrallography and NMR spectroscopy
what is the secondary protein structure
alpha helicies, and beta pleated sheets
what is the structure of an alpha helix
clockwise spiral
each C=O is hydrogen bonding to H-N group 4 amino acid residues down
each turn contains 3.5 amino acid residues
what hinders helix formation
proline
large buly side chains
multiple side chians of like charge
what amino acids are often found in alpha helices
alanine, leucine, methionine
