Metabolic fuels and precursors EC Flashcards
Why are intracellular carbohydrates phosphorylated?
To keep them from diffusing out of the cell
Which isomer are most human sugars?
D isomer
What are reducing sugars?
Open chain forms that allow carbonyl group to react with reducing agents
Glucuronic acid
Reacts with unconjugated bilirubin to form conjugated
Component of GAGs (glycosaminoglycans)
Sorbital derived damage in diabetes
Lens (cataracts)
Schwann cells (peripheral neuropathy)
Pericytes (retinopathy)
Maltose
Glucose + Glucose
Lactose
Glucose + Galactose
Sucrose
Glucose + Fructose
Monosacharides
Glucose, Fructose, Ribose
“GFR”
Disaccharides
Maltose, Lactose, Sucrose
“MLS”
Essential fatty acids
Linoleic acid (18C) Linolenic acid (18C)
Carnitine shuttle
Moves long chain fatty acids from cytosol to mitochondria
deficiency results in nonketotic hypoglycemia
Corticosteroids effect on phospholipids
Inhibit phospholipase A2, inhibit arachadonic acid release
Gly (glycine)
Smallest amino acid
Inhibitory neurotransmitter in spinal cord
Synthesis of heme
Abundant in collagen
Ala (alanine)
Alanine cycle during fasting: major substrate for gluconeogenesis
Val (valine)
Branched
Not degraded by liver
Used in muscle
Increased in maple syrup urine disease
Leu (leucine)
Branched Not degraded in liver Ketogenic Used in muscle Increased in maple syrup urine disease
Ile (isoleucine)
Branched
Not degraded by liver
Used in muscle
Increased in maple syrup urine disease
Met (methionine)
Polypeptide chain initiation Methyl donor (as S-adenosylmethionine)
Pro (proline)
Helix breaker
Only a.a. with side chain cyclized to alpha amino group
Hydroxylation in collagen via ascorib acid
Binding site for collagen cross-bridges
Phe (phenylalanine)
Increased in PKU
Aromatic side chain (increased in hepatic coma)
Tyr>Dopa(malanin)>Dopamine>NE>Epi
Trp (tryptophan)
Precurser to serotonin, niacin, and melotonin
Aromatic side chains (increased in hepatic coma)
Cys (cysteine)
Forms disulphide bonds
Sensitive to oxidation
Component of glutathione (RBC antioxidation)
Deficient in G6PD deficiency
Ser (serine)
Single carbon donor
Phosphorylated by kinases
Thr (threonine)
Phosphorylated by kinases
Tyr (tyrosine)
Precursor to melatonin, catacholamines, and thyroid hormones
Phosphorylated by kinases
Aromatic side chain (increased in hepatic coma)
Must be supplied in PKU
Signal transduction (tyrosine kinase)
Asn (asparagine)
Insufficiently synthesized by neoplastic cells
Used to treat leukemia
Gln (glutamine)
Most abundant
Nitrogen carrier
NO donor in purine/pyrimidine synthesis
NH3 detox. in brain and liver
Fasting state: carries amino group from muscle to other tissue
Fasting state: fuel for kidneys, intestine, and immune system
Lys (lysine)
Basic
Ketogenic
Abundant in histones
Hydroxylation in collagen aided by ascorbic acid
Binding site for cross-bridges in protocollagen
Arg (arginine)
Basic
Essential for growth in children
Abundant in histones
Precursor to creatine, urea, & NO
His (histidine)
Basic: ZERO charge at pH=7.4 Physiologic buffer Histamine precursor Residue in Hg coordinated with heme Essential for growth in children
Asp (aspartate)
Acidic
Forms oxaloacetate by transamination
Important for albumin binding properties
Glu (glutamate)
Acidic
Forms alpha-ketoglutarate by transamination
Important for binding properties of albumin
GABA and Glutathione precursor
