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Organic compounds containing nitrogen and sulfur

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Presentation on theme: "Organic compounds containing nitrogen and sulfur"— Presentation transcript:

1 Organic compounds containing nitrogen and sulfur
Alice Skoumalová

2 Nitrogen compounds Types of bonds in nitrogen compounds:

3 Nitro compounds: R-NO2 Hydrogen substituted for NO2
Originate from nitration of aromatic hydrocarbons (HNO3) Examples: chloramphenicol (antibiotic) trinitrotoluene

4 Amines: R-NH2 organic derivates of ammonia Quaternary ammonium salts
Nitrogen heterocyclic compounds Amines: R-NH2 -NH NH N-

5 Properties of amines: basicity of amines (the unshared pair of electrons on the nitrogen atom) form hydrogen bonds (the polarity of the carbon-nitrogen bond) form nitrosoamines (nitrites in food may cause cancer) nitrosoamine

6 Importance of amines: The most important organic bases
In biochemistry: Quaternary ammonium salts Biogenic amines Amino acids Proteins Alkaloids

7 Quaternary ammonium salts:
Choline: Acetylcholine: - the constituent of phospholipids (lecithin) - neurotransmiter (parasympathetic nervous system)

8 Acetylcholine - the transmitter of the parasympathetic and sympathetic system, at neuromuscular junctions, involved in learning and memory 1. The synthesis: from choline and acetyl-CoA in the neurons 2. Hydrolysis: in the synaptict cleft (restores the resting potential in the postsynaptic membrane)

9 Biogenic amines: from amino acids by decarboxylation
constituents of biomolecules, neurotransmitters Amino acid Amine Function Serine Ethanolamine Phospholipids Cysteine Thyoethanolamine Component of coenzyme A Threonine Aminopropanol Component of vitamin B12 Aspartate β-Alanine Glutamate γ-Aminobutyrate Neurotransmitter (GABA) Histidine Histamine Mediator, neurotransmitter Dopa Dopamine Neurotransmitter 5-hydroxytryptophan Serotonin

10 Biogenic amines – examples:

11 Adrenaline and amphetamines:
Catecholamines (adrenaline and noradrenaline) biogenic amines with catechol group derived from tyrosine hormones (the adrenal medulla), neurotransmitters (sympathetic nervous system) Amphetamines mimic the action of catecholamines stimulate the cortex (abuse)

12 Alkaloids: naturally occurring chemical compounds containing basic nitrogen atoms important biological properties Examples: Atropine – blocks acetylcholine receptors Cocaine – stimulative effect Reserpine – sedative Ephedrine – bronchodilator

13 Opium and opiates: = morphine alkaloids important in medicine, abuse
bind to the opioid receptors Examples: Opium, morphine – analgetic, the immature seed pods of opium poppies Codeine – analgetic, antitussive Heroin – synthesizes from morphine Search similar compounds (without addiction):

14 Amides: R-CO-NH2 an amino group or substituted amino group bonded to a carbonyl carbon Properties: not basic (the carbonyl group draws electrons away from the nitrogen) formation of the peptide bond –NH2 + HOOC- (enzyme-catalyzed) The great stability toward hydrolysis (the peptide bond is stable, enzymatic hydrolysis)

15 Important amides in medicine:
asparagine, glutamine urea, carbamate, creatine nicotinamide – coenzyme NAD peptides barbiturates

16 Asparagine, glutamine:
The peptide bond:

17 Carbamate and urea Carbamoyl phosphate = carbonic acid amides (H2CO3)
- intermediate in: urea cycle the formation of pyrimidines

18 Urea the end-product of protein metabolism in mammals
produced only in the liver (urea cycle) soluble in water (excreted in the urine) electron delocalization → weak acid biuret test (detection of peptide bonds and urea) - heating - biuret in alkaline environment with Cu2+ - purple

19 Fate of amino acid nitrogen = urea synthesis:
Urea nitrogen from: 1. NH4+ 2. aspartate

20 Creatine Creatinine In muscle metabolism, energy for contraction
In a nonenzymatic reaction from creatine Excreted in the urine

21 Creatine metabolism:

22 Barbiturates Barbituric acid derivates:
sedatives, hypnotics, narcotiks

23 Imines: R-C=N-R Schiff bases
functional group that contains a carbon-nitrogen double bond with the nitrogen atom connected to an aryl or alkyl group charged Mechanism of transamination:

24 Sulfur compounds Structurally similar to oxygen compound

25 Thiols: R-SH (sulfhydryl group)
Properties: Not form hydrogen bonds Stronger acids than alcohols Easily oxidized → disulfide Examples: Cystein

26 Disulfides: R-S-S-R Disulfide-bonded cystein residues
The disulfide bond forms when the two thiol groups are oxidized (reverse reaction) Protein conformation!

27 Glutathione An antioxidant (elimination of H2O2 and organic hydroperoxides) Glutathione peroxidase Gly Cys Glu Gly Cys Glu Gly Cys SH Glu + R-O-O-H S S + H2O + NADPH Glutathione reductase Reduced form of glutathione (monomer) Oxidized form of glutathione (dimer, disulphide)

28 Sulfides: R-S-R Examples: Methionine S-Adenosylmethionine (SAM)
= sulfonium ion Highly reactive methyl group (an important methylation agent)!

29 Sulfonic acids: R-SO3H Examples: Taurin = derivate from cysteine
Sulfonamides important chemoterapeutics

30 Summary Nitrogen compounds: 1. Amines 2. Amides 3. Imines
neurotransmitters (GABA, dopamine, serotonine, catecholamines, acetylcholine) amino acids alkaloids (cocaine, opiates) 2. Amides peptide bond urea creatine 3. Imines Schiff bases Sulfur compounds 1. Thiols - disulfide glutathione, proteins 2. Sulfides S-adenosylmethionine 3. Sulfonic acid Taurin

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