Proteins Metabolism Flashcards
Kwashiorkor
Protein deficiency but adequate calories
Famine edema
Inadequate synthesis of plasma proteins, mostly albumin, so fluid escape into tissues
Marasmus
Protein energy malnutrition
Protein calorie deficiency
Starvation
Protein malnutrition causes in developed countries
Prégnant and lactating mothers Eating disorders Alcoholism Drug addicts Hospital patients Elderly and chronically ill Genetic disorders
Essential amino acids
Mnemonic PVT TIM HALL
Arg His Île Leu Lys Met Phy Thr Trp Val
Non essential amino acids
Ala Asn Asp Cys Glu Gln Gly Pro Ser Tyr
Amino acids requirements
No significant storage
Depends on age sex and activity
2 fates of amino acids degradation
Amino acids can produce NH4 or carbon skeleton
NH4 can
- enter biosynthesis of AA, nucleotides, amines
- enter urea cycle
Carbon skeleton become a-ketoacids which can enter citric acid cycle —> OAA can be formed and undergo gluconeogenesis
What is glycogenic AA
Product of AA degradation can enter gluconeogenesis
Ketogenic AA degradation
Ketogenic AA degradation products are intermediates of lipid metabolism or ketone bodies
AA purely ketogenic
Leucine
Lysine
AA both ketogenic and glucogenic
Isoleucine
Phenylalanine
Tyrosine
Tryptophan
Products of glucogenic AA breakdown
Pyruvate a-ketoglutarate Succinyl coa Fumarate OAA
Products of ketogenic AA breakdown
Acetyl coa
Acetoacetate
Healthy adult nitrogen balance
Excretion of nitrogen equals intake
4 majors reaction of AA
Transamination
Oxidative deamination
Decarboxylation
Transdeamination
Transamination
Transfer of NH2 to form another AA
Enzyme in transamination
Transaminase
AA1+ aketoacid 2<===> aketoacid1+ AA 2
Transaminase cofactor
Pyridoxal phosphate derived from vit b6
Major AA In AA metabolism
aketoglutarate
Gln
Glutamate
Most abundant AA serving as neural transport and storage form of ammonia
Glutamine
Glutamate dehydrogenase action
Glutamate + NADP+ H2O <==> aketoglutarate+ NADPH + NH4+
Glutamine synthétase action
Glutamate + ATP + NH4+ —-> glutamine + ADP + pi
Glutaminase action
Glutamine —-> glutamate
Amino Acid oxidase
Amino acid + FAD + H2O —-> aketo acid +NH3 + FADH2
FADH2 + O2 —-catalase—> FAD + H2O2
Decarboxylation
CO2 removed from glutamate to form GABA
Transdeamination
Coupling of aminotransferase with glutamate dehydrogenase
Lead to formation of pyruvate
Tryptophan metabolized to
Alanine
Acetyl coa
CO2
Formate
Small amount to serotonin , niacin, melatonin
AA precursors of
Protein synthesis
Active metabolites
Metabolic fuels
Serotonin
Neurotransmitter which impacts behavior such as appetite , aggression, sleep, sensory perception, depression
Potent vasoconstrictir of
Blood vessels’
Helps in circadian cycle
Antidepressants that inhibits serotonin reuptake
Paxil
Prozac
Zoloft
…… is a structural agonist that potential es effect of serotonin
LSD
Hartnups disease
Defect in transportation or absorption of AA in intestines
Defect in reabsorption un renal tubules of kidney
High urine concentration of essential amino acids
Symptoms :
Hereditary pellagra like skin rash
Cerebellar ataxia temporary
Constant renal amino aciduria
3 D
Dermatitis
Dementia (20%)
Diarrhea
Direct source of ammonia in liver
Glutamate
Glutamine ( from other tissues)
Alanine ( from muscles )
Major contributor to waste nitrogen
Muscle
Nitrogen waste products
Urea in vertebrates
Uric acid in birds and reptiles
Carbamoyl phosphate synthesis and entry into urea cycle
HCO3- + NH4+ gives carbamoyl phosphate
