Nitrogen and Phosphorus Containing compounds Flashcards
What makes glycine unique among amino acids
All amino acids except glycine have a chiral alpha carbon. Because the R group of glycine is a hydrogen atom, it is not chiral and therefore is not optically active.
Amino acids are amphoteric. What does that mean? what functional groups give amino acids this characteristic?
Amphoteric molecules can act as acids or bases. Carboxylic acids give amino acids their acidic properties because they can be deprotonated. Amino groups give amino acids their basic properties because they can be protonated.
How are peptide bonds formed and cleaved?
Peptide bonds are formed by a condensation reaction, in which a water is lost, and cleaved hydrolytically by strong acid or base (hydrolysis, add water)
Why is the C-N bond of an amide planar?
The C-N bond of an amide is planar because it has partial double-bond character due to resonance. double bond exist in a planar conformation and restrict movement.
What are the ways to make amino acids?
Streker synthesis
Gabriel synthesis
What are the 4 reactants in the strecker synthesis of an amino acid
An aldehyde or ketone, ammonium chloride (NH4Cl), and potassium cyanide (KCN) are used to make the amonionitrile; water is used to hydrolyze the aminonitrile to form the amino acid.
What are the reaction types used in the strecker synthesis
Strecker synthesis is a condensation reaction ( forming of an imine from a carbonyl-containing compound and ammonia, while the loss of water), followed by hydrolysis
What are the four main reactants in the Gabriel synthesis of an amino acid?
Gabriel synthesis begins with potassium phthalimide and diethyl bromomalonate, followed by an alkyl halide. Water is then used to hydrolyze the resulting a compound to form the amino acid. While acids and bases are used at various points in the reaction they are not main reactants.
What are the reaction types used in the Gabriel synthesis?
Gabriel synthesis proceeds via two SN2 reactions, hydrolysis and decarboxylation
Strecker synthesis description
- An aldehyde is mixed with ammonium chloride (NH4Cl) and potassium cyanide. The ammonia is attacks the carbonyl carbon, generating an imine. The imine is then attack by cyanide, generating an aminonitrile
- The amino nitrile is hydrolyzed by 2 equivalents of h20, generating an amino acid
Gabriel Synthesis description
- It generates an amino acid from potassium phathalimide, diethyl bromomalonate, and an alkyl halide
- Phthalimide attacks the diethyl bromomalonate, generating a phthalimidomalonic ester
- The phthalimidomalonic ester attacks an alkyl halide, adding an alkyl group to the ester
- The product is hydrolyzed, creating phthalic acid ( with two carboxyl groups) and converting the esters into carboxylic acids
- One carboxylic acid of the resulting 1,3-dicarbonyl is removed by decarboxylation
What characteristic make inorganic phosphate so useful for energy transfer biologically?
Inorganic phosphate contains a very negative charge. When bonded to other phosphate groups in a nucleotide triphosphate, this creates repulsion with adjacent phosphate groups, increasing the energy of the bond. Further, inorganic phosphate can be resonance-stabalized
What is an organic phosphate?
Organic phosphate are carbon-containing molecules with phosphate groups; the most common examples are nucleotides like those in DNA, ATP, or GTP
What characteristics of phosphoric acids make them good buffers?
They have 3 hydrogens in phosphoric acid have very different pKa values. This allows phosphoric acid to pick up or give off protons in a wide pH range, making it a good buffer over most of the pH scale.
