Amino Acids (structure a propert.) Flashcards
Give the general structure of amino acid
- R (side chain) connected with Carbon (alpha carbon) (R not counted in the common group)
- H connected with Carbon
- COOH (carboxyl end) connected with Carbon
- NH2 (amino end) connected with Carbon
- tetrahedral structure
How many different proteins can be created by H,C,N,O,S
- 20 amino acids that then build all the proteins they need
- >different side chains R, determine the properties of 20 amino acids
How are amino acids formed?
-Amino acids are derivatives (entstanden durch) of carboxylic acids formed by substitution of α-hydrogen for amino functional group
What does each amino acid have? + except which one?
- a carboxyl group
- an amino group
- a H atom and
- a side chain (R group)
- except for proline
Which amino acid is created if the R-group is replaced with H or CH3?
- H= Glycine
- CH3= Alanine
What is L- and D-Form standing for? And where do they appear?
- L- and D- forms, analogous to left-handed and right-handed configurations
- Only L-amino acids are manufactured in cells and incorporated into proteins
- Some D-amino acids are found in the cell walls of bacteria, but not in bacterial proteins
How many different amino acids have been described in nature?
-more than 300
How many amino acids are commonly found as constituents of mammalian proteins?
-only 20 (22 and more?)
Pyrrolysine (not found in human) and Selenocysteine
What codes the amino acids which are constituents of mammalian protein?
-These are the only amino acids that are coded by DNA
What is a chiral?
-The α-carbon of each amino acid is attached to four different chemical groups and is, therefore, a chiral or optically active carbon atom
What are optically active amino acids able to do?
-Optically active amino acids rotate-plane (rotieren) polarized light
Which amino acid is not optically and why?
-glycine is optically inactive because its α-carbon is attached two hydrogen atoms (not chiral)
What are asymmetric carbons?
-a carbon atom with four different substituents is said to be asymmetric, and asymmetric carbons are called chiral centers
Why are the amino acids not superimposable with their mirror images? (+which amino acid is superimposable?)
- are optically active molecules and asymmetric
- glycine where the R-group is hydrogen
According to the new UIPAC nomenclature L-D- forms were replaced with what?
-S- and R-system
