proteins 2 Flashcards
what Is N linked glycosylation
- amide of an asparagine
- site Asn-x-Ser/Thr
- occurs in ER lumen
what is O linked glycosylation
- hydroxyl group of serine or threonine
- glycosylated in the golgi lumen
what does oligosaccharyltransferase do
- glycosylates proteins in the ER lumen
what are the stages of glycoprotein degradation
- endocytosis to lysosome from cell surface
- proteins degrades via proteases
- remove sugars by lysosomal glycosidases
what occurs with lysosomal hydrolases deficiency
- lysosomal storage diseases
- undigested substrates in lysosomes
- defects often leads to nervous system defects causing changed cell signalling and decrease mitochondrial function and low ATP
what are the causes and symptoms of inclusion cel disease
- recessive mutation causing hydrolytic enzymes missing - failed sorting in golgi so lysosomal hydrolases found in blood
symptoms - small, weak muscle tone, bone abnormalities, high mortality, slow growth, coarse facial features and overgrowth of gums
what are glycosaminoglycans (GAGs) made from
- contains unbranched polysaccharides
- with amino sugars and acidic disaccharide repeats
- long and linear
what are proteoglycans made from
- glycoproteins with GAGs
- up to 95% GAG in weight
how are GAGs assembled on a protein
- tetrasaccharide added at serine in golgi
- repeats added one sugar at a time
what are the functions of proteoglycans
- lubricants in connective tissue
- cell adhesion to extracellular matrix
- bind cell proliferation factors
what are the stages of glycosaminoglycans degradation
- endocytosis
- remove sugars - lysosomal glycosides
what are biogenic amines
- small organic nitrogen containing molecules
- synthesised from amino acids
what are the classes of biogenic amines
- aromatic and hetrocyclic
- aliphatic - mono, di, tri, poly amines
- aliphatic volatile amines
what are the functions of biogenic amines
- cell membrane stabilisation
- immune functions and inflammation mediators
- nucleic acid and protein synthesis
- hormones
- neural transmission
what reactions make biogenic amines
- decarboxylation of amino acids
- amination and transamination of aldehydes and ketones
what is the biogenic amine of serine
- sphingosine
what is the biogenic amine of histidine
- histamine
what is the biogenic amine of tryptophan
- serotonin and nicotinamide and 5-hydroxytryptamine (5-HP)
what is serotonin used for
- relaxation, pleasure, memory
what is nicotinamide used for
- vitamin B3
- coenzyme and energy production
what biogenic amine does tyrosine make
- adrenaline and thyoxine
what is adrenalin used for
- hormone
- fight or flight response
- neurotransmitter
what is thyroxine used for
- thyroid gland hormone
- activated to triiodothyronine
- metabolic rate, muscle control, brain development, bone maintenance
describe the catecholamine synthesis pathway
1) tyrosine
2) dihydroxyphenylalanine
3) dopamine
4) norepinephrine
5) epinephrine
what is the rate limiting stage in catecholamine synthesis
- tyrosine hydroxylate - stage 1
- co-substrate - oxygen
- cofactor - tetrahydrobiopterin
what causes IBS
increased monoamine oxidase activity —> oxidative stress —> vascular dysfunction
what does monoamine oxidase A deficiency cause
- serotonin build up in the brain —> loss of impulse control
- avoid high thymine food
what does vitamin B12 - folate deficiency cause
- required for FAD—> monoamine oxidases disfunction –> tiredness, disturbed vision, psycgological problems
what does monoamine oxidases (MAO) do
- family of enzymes
- deaminates neurotransmitters
- requires prosthetic group - flavin adenine dinucleotide (FAD)
