BioChem Enzymes Flashcards

Learn the 13 key enzymes involved in metabolism. Listing both their inhibitors and activators

1
Q

Hexo/Glucokinase

A

First step of glycolysis. Phosphorylates glucose to glucose 6 phosphate. Locks glucose into cell
Hexokinase: Inhibited by product G6P
NB: Inhibition of PFK leads to build up of G6P

Glucokinase (in liver): has higher Km then hexokinase
NB: not inhibited by products

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2
Q

PFK

A

comitted step in glycolysis phorphorylates F6P->F16BP
Regulation: High ATP inhibits,
High AMP activates

Liver: Stimulated by F26BP F6P->F26BP by PFK2
inhibited by citrate

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3
Q

Pyruvate Kinase

A

Last step in glycolysis breaks down PEP to Pyruvate
Regulation: Inhibited by ATP, alanine
Activated by F16BP via feed forward mechanism

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4
Q

Pyruvate Dehdrogenase Complex

A

Large complex that converts pyruvate into Acetyl CoA after pyruvate has been shuttled into mitochondria
Reguatlion: phosphorylated and innactive
phorsphorylation increased by NADH, ATP and Acetyl CoA
Dephosphorylated and active. Phosphatase activity is increased by ADP, Pyruvate and Ca++

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5
Q

Isocitrate Dehydrogenase

A

Step in TCA cycle takes isocitrate to A-ketoglutarate with CO2 and NADH
Regulation: Inhibited by ATP and NADH. Leads to build up of citrate via aconitase converting isocit to cit
Cit inhibits PFK and acts as source of Acetyl CoA for FAS

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6
Q

Carnitine Shuttle

A

FA -> Acyl CoA via Acyl CoA synthetase
Carnitine shuttles acyl CoA across the inner mitochondrial membrane for FA degredation
Carnitine is recylced
Inhibited by malonyl CoA (precurrsor for FA synthesis)

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7
Q

Acetyl CoA Carboxylase

A

Enzyme that transforms Acetyl CoA to Malonyl CoA for FAS
Regulation: AMP dependent protein kinase inactivates
Phosphatase activates
Citrate activates even inactive form
Insulin Stimulates
Glucagon, Epinephrine inhibit ACC

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8
Q

Fatty Acid Synthase

A

Links malonyl CoA to Acetyl CoA to form long fatty acids. Need Malonyl ACP and Acetyl ACP

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9
Q

Adipose Tissue Lipase

A

Hormone Sensitive Lipase and Perilipase involved in FA degredation
Regulation: Epinephrine/ glucagon stimulate

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10
Q

Fructose 1,6 Biphosphatase

A

Enzyme that cleaves off phosphate in gluconeogenesis to form Fructose 6 Phosphate.
Inhibited by F26BP, AMP
Activated by citrate

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11
Q

Pyruvate Carboxykinase

A

First step in gluconeogenesis takes pyruvate to OAA. OAA can be shuttled out of the mitochondria in the form of malate. Uses ATP
Inhibited by ADP
Activated by Acetyl CoA

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12
Q

Glycogen Phosphorylase

A

Enzyme involved in breaking down glycogen
Takes piece of gylcogen and cleaves it to form glucose 1 phosphate
glucose 1 phosphate -> G6P via phosphoglucomutase
Regulation: Inhibited by G6P and ATP
Insulin leads to T state (less active) dephosphorylates a to b form
Glucagon leads to R state (more active)via phosphorylation of b form

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13
Q

Glycogen Synthase

A

Builds glycogen molecule from UDP-glucose monomers. Requires primer glycogenin
Regulation: Phosphorylated and deactivated
Dephosphorylated and active
Activated by G6P

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14
Q

Lipoprotein Lipase

A

Found in the lumen of the blood vessles. Breaks down FA carried on serum albumin. Allows for transport of FA into cells as FFA and monoacylglycerol

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15
Q

PEP Carboxykianse

A

Converts OAA into PEP. Uses GTP

Regulation: Inhibited by ADP

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