Biochemistry Midterm

• Protein - is naturally occuring unbranched polymer, in which monomer unit contains amino acids.
• Protein - contains Oxygen, Nitrogen, Hydrogen, sulfuric acid, iron and also phosporus.
• Amino acids - an organic compound contains (NH2) amino and (COOH) carboxyl acid.
• The position of carbon atom is in Alpha (a)
• (NH2 or amino) attached to Alpha (a) carbon atom.
• (COOH or carboxyl acid) attached also to Alpha (a) carbon atom.
• The average Nitrogen content of protein is 15.4 by mass.
• More than 700 amino acids are known.
• Based on the R group, there are 20 standard amino acids.
• Non-polar amino acids - is a hydrophobic or water fearing.
• Polar amino acids - is a hydrophilic or water loving.
• Non polar amino acids sub-types - alkyl and aromatic.
• Polar amino acids sub-types - neutral, acidic and basic.
• Polar amino acids - R-groups are polar.

  Three types -

  • polar neutral
  • polar acidic
  • polar basic
• Polar neutral - contains polar but neutral side chains, and seven amino acids are belong to this group or category.
• Polar acidic - contains carboxyl group as part of the side chain, and two amino acids are belong to this group or category.
• Polar basic - contains amino group as part of the side chain, also two amino acids are belong to this group or category.
• Nomenclature :

  One-letter symbols - commonly used for comparing the sequence amino acids by protein, the most abundant amino acids gets the 1st letter.
• Glycerine R-groups is hydrogen.
• Four different groups are attached to amino acids in all of the standard amino acids except glycerine.
• 19-20 amino acids are containing chiral center.
• Each of the 19 amino acids exist in left and right handed forms.
• Chiral center exhibit enantiomers.
• The amino acids found in the nature as well as in protein is L-isomers.
• Bacteria do have some D-amino acids.
• Monosaccharide nature favors D-isomers.
• Fisher projection formula rule - the COOH is at the top, the R-GROUP at the bottom to position carbon chain vertically.
• NH2 at the left is L-isomers.
• NH2 at the right - D-isomers.
• in pure form amino acids are white crystalline solid.
• most amino acids are decompose before they melt.
• Carboxyl group gives up proton to get the negative charges.
• Amino groups accepts proton to become positive.
• Cysteine - the only standard amino acids with sulfhydryl group.
• Dipeptides - bond between 2 amino acids.
• Oligopeptides - bond between to 10-20 amino acids.
• Polypeptides - bond to larger number of amino acids.
• Peptides - Linked Amino acids is called peptides.
• Peptide bonds - covalent bond between amino acid acid and peptides.
• Unbranched amino acids - produce by amino acid bonds together.