Stage (Location) - UCSB



Stage (Location) |From our food… | |

|1 Digestion (stomach & |Fats |Carbohydrates (glycogen, starch) |Proteins |

|intestines) | | | |

| |+ 3 H2O |+ H2O |+ H2O |

| |↓ |↓ |endo and exopeptidases ↓ |

| |(Sect. 25.6, Fig 25.3) |(Sect. 25.7, Fig 25.4) | |

| |[pic] |[pic] |[pic] |[pic] |

| |3 Fatty Acids |Glycerol |Glucose (monosaccharides) |Phe as example |

| | | | |(Amino Acids) |

|2 Formation of Acetyl-CoA |acyl-CoA synthase |glycerol kinase |hexokinase |phenylalanine hydroxylase ↓ |

| |↓ CoASH → ADP, HPO42- |↓ ATP, Mg2+ → ADP |↓ ATP, Mg2+ → ADP | |

| |[pic] |[pic] |[pic] |[pic] |

| |fatty acid acyl-CoA (a thioester) |glycerol-3-phosphate |glucose-6-phosphate |Tyr |

| |acyl-CoA dehydrogenase | |phosphoglucose isomerase ↓↑ |tyrosine aminotransferase |

| |↓ FAD → FADH2 | | |↓ PLP |

| | [pic] | |[pic] |[pic] |

| |α,β-unsaturated fatty acid acyl-CoA | |fructose-6-phosphate |p-hydroxyphenylpyruvate |

| |enoyl-CoA hydratase | |phosphofructokinase |p-hydroxyphenylpyruvate dioxygenase |

| |↓ H2O | |↓ ATP, Mg2+ → ADP |↓ |

| |[pic] | |[pic] |[pic] |

| |β-hydroxy fatty acid acyl-CoA | |fructose-1,6-diphosphate |homogentisate |

| |3-L-hydroxyacyl-CoA dehydrogenase |glycerol phosphate dehydrogenase |aldolase ↓↑ |homogentisate dioxygenase |

| |↓ NAD+ → NADH, H+ |↓ NAD+ → NADH, H+ | |↓ |

| |[pic] |[pic] |[pic] [pic] |↓ |

| |β-keto fatty acid acyl-CoA |dihydroxyacetone phosphate | | |

| | |(can enter glycolysis) |dihydroxyacetone [pic] glyceraldehyde-3- phosphate phosphate | |

| |β-ketoacyl-CoA thiolase | |glyceraldehydes-3-phosphate dehydrogenase |↓ |

| |↓ CoASH | |↓↑ NAD+ + HPO42- → NADH, H+ | |

| | | |[pic] |[pic] + [pic] |

| | | |1,3-diphosphoglycerate |Acetyl-CoA + fumarate |

| | | | | |

| | | | | |

| | | | | |

| |[pic] + [pic] | | | |

| |Fatty Acyl-CoA + Acetyl-CoA | | | |

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| | | | | |

| | | | | |

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| | | |phophoglycerate kinase | |

| | | |↓↑ ADP → ATP | |

| | | |[pic] | |

| | | |3-phosphoglycerate | |

| | | |phosphoglycerate mutase ↓↑ | |

| | | |[pic] | |

| | | |2-phosphoglycerate | |

| | | |enolase ↓↑ | |

| | | |[pic] | |

| | | |phosphoenol pyruvate + H2O | |

| | | |pyruvate kinase | |

| | | |↓↑ ADP → ATP | |

| | | |[pic] | |

| | | |Pyruvate | |

| | | |Overall Reaction: glucose → 2 pyruvate + 2 ATP + 2 NADH | |

| | | |pyruvate dehydrogenase system/complex | |

| | | |↓ TPP, lipoate, CoASH, FAD, NAD+ | |

| | | |[pic] | |

| | | |Acetyl-CoA + CO2 | |

| | | |Overall Reaction: pyruvate → acetyl-CoA + CO2 + NADH | |

| | | | | |

|3 Citric Acid Cycle, Kreb’s |[pic] |

|Cycle (mitochondria) | |

|Sect. 25.10 |Overall Reaction: Acetyl-CoA → 2 CO2 + 3 NADH + GTP + FADH2 |

|4 Oxidative Phosphorylation |GTP + ADP [pic]GDP + ATP |

|(mitochondria) |NADH[pic]NAD+ + 3 ATP |

|Sect. 25.11 |FADH2 [pic]FAD + 2 ATP |

Another way of looking at the catabolism of fats:

|Step |Reaction (type) |Enzyme |Coenzyme |

|1 |fat + 3 H2O → glycerol (see below) + 3 fatty acids (hydrolysis) | | |

|2 |fatty acid + CoASH + ATP → fatty acid acyl-CoA + ADP, HPO42- (formation of thioester) |acyl-CoA synthase | |

| | | |CoASH |

|3 |fatty acid acyl-CoA + FAD → α,β-unsaturated fatty acid acyl-CoA + FADH2 (oxidation) |acyl-CoA dehydrogenase |FAD |

|4 |α,β-unsaturated fatty acid acyl-CoA + H2O → β-hydroxy fatty acid acyl-CoA + H+ (hydration) |enoyl-CoA hydratase | |

|5 |β-hydroxy fatty acid acyl-CoA + NAD+ → β-keto fatty acid acyl-CoA + NADH + H+ (oxidation) |3-L-hydroxyacyl-CoA dehydrogenase |NAD+ |

|6 |β-keto fatty acid acyl-CoA + CoASH → acetyl-CoA + fatty acid acyl-CoA |β-ketoacyl-CoA thiolase |CoASH |

| |(return to step 3 and continue removing 2 Cs from fatty acid acyl-CoA as acetyl-CoA.) | | |

| | | | |

|1g |Glycerol + ATP → glycerol-3-phosphate + ADP |glycerol kinase |Mg2+ |

|2g |Glycerol-3-phosphate + NAD+ → dihydroxyacetone phosphate + NADH |glycerolphosphate dehydrogenase |NAD+ |

|3g |dihydroxyacetone phosphate [pic]glygeraldehyde-3-phosphate |triosephosphate isomerase | |

|4g+ |glygeraldehyde-3-phosphate can join glycolysis pathway to form pyruvate → acetyl-CoA | | |

|Overall: 3 FA acyl-CoA + glycerol →3 shorter FA acyl-CoA + 4 acetyl-CoA + 5 NADH + 3 FADH2 + 2 ATP |

Another way of looking at Glycolysis:

|Step |Reaction (type) |Enzyme |Coenzyme |ΔGo (kcal/mol) |

| | | | |[ΔGo = -28.9] |

|1 |glucose + ATP → glucose-6-phosphate + ADP + H+ (phosphoryl transfer) |hexokinase |Mg2+ |-4.0 |

|2 |glucose-6-phosphate [pic]fructose-6-phosphate (isomerization) |phosphoglucose isomerase | |+0.4 |

|3 |fructose-6-phosphate + ATP → fructose-1,6-diphosphate + ADP + H+ (phosphoryl transfer) |phosphofructokinase |Mg2+ |-3.4 |

|4 |fructose-1,6-diphosphate [pic]dihydroxyacetone phosphate + glyceraldehyde-3-phosphate (aldol cleavage) |aldolase | |-5.7 |

|5 |dihydroxyacetone phosphate [pic] glyceraldehyde-3-phosphate (isomerization) |triosephosphate isomerase | |+1.8 |

|6 |2 glyceraldehyde-3-phosphate + 2 HPO32- + 2 NAD+ [pic]2 1,3-diphosphoglycerate + 2 NADH + 2 H+ (phosphorylation, |glyceraldehyde-3-phosphate dehydrogenase |NAD+, HPO32- |2(+1.5) = +3.0 |

| |oxidation) | | | |

|7 |2 1,3-diphosphoglycerate + 2 ADP[pic]2 3-phosphoglycerate + ATP (phosphoryl transfer) |phosphoglycerate kinase | |2(-4.5) = -9.0 |

|8 |2 3-phosphoglycerate [pic]2 2-phosphoglycerate (phosphoryl shift, isomerization) |phosphoglycerate mutase | |2(+1.1) = +2.2 |

|9 |2 2-phosphoglycerate [pic]2 phosphoenolpyruvate + 2 H2O (dehydration) |enolase | |2(+0.4) = +0.8 |

|10 |2 phosphoenolpyruvate + 2 ADP + 2 H+ → 2 pyruvate + ATP (phosphoryl transfer) |pyruvate kinase | |2(-7.5) = -15.0 |

|Overall: glucose → 2 pyruvate + 2 NADH + 2 ATP / glucose → 2 acetyl-CoA + 4 NADH + 2 ATP |

Other ways of looking at the Citric Acid Cycle:

[pic]

|Step |Reaction (type) |Enzyme |Coenzyme |ΔGo (kcal/mol) |

| | | | |[ΔGo = -9.4] |

|1 |acetyl-CoA + oxaloacetate + H2O → citrate + CoASH + H+ (condensation) |citrate synthase | |-7.5 |

|2 |citrate [pic]isocitrate (isomerization) |aconitase |Fe-S |+1.5 |

|3 |isocitrate + NAD+ [pic]α-ketoglutarate + CO2 + NADH + H+ (decarboxylation, oxidation) |isocitrate dehydrogenase |NAD+ |-2.0 |

|4 |α-ketoglutarate + NAD+ + CoASH [pic]succinyl-CoA + CO2 + NADH + H+ (decarboxylation, oxidation) |α-ketoglutarate |(Lipoate, FAD, TPP), |-7.2 |

| | |dehydrogenase |NAD+ | |

| | |(system/complex) | | |

|5 |succinyl-CoA + HPO32- + GDP [pic]succinate + GTP + CoASH (phosphorylation) |succinyl-CoA synthase | |-0.4 |

|6 |succinate + FAD [pic]fumarate + FADH2 (oxidation) |succinate dehydrogenase |FAD, Fe-S |0 |

|7 |fumarate + H2O [pic]L-malate (hydration) |fumarase | |-0.9 |

|8 |L-malate + NAD+ [pic]oxaloacetate + NADH + H+ (oxidation) |malate dehydrogenase |NAD+ |+7.1 |

|Overall: acetyl-CoA → 2 CO2 + 3 NADH + FADH2 + GTP |

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